Oxamate

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Miguel Julve - One of the best experts on this subject based on the ideXlab platform.

  • 2D and 3D mixed MII/CuII metal–organic frameworks (M = Ca and Sr) with N,N′-2,6-pyridinebis(Oxamate) and oxalate: preparation and magneto-structural study
    Dalton transactions (Cambridge England : 2003), 2018
    Co-Authors: Tamires S. Fernandes, Francesc Lloret, Wanessa D C Melo, Lucas H. G. Kalinke, Renato Rabelo, Ana Karoline Silva Mendanha Valdo, Cameron Capeletti Da Silva, Felipe T. Martins, Pedro Amorós, Miguel Julve
    Abstract:

    Three heterobimetallic complexes of formula [Ca2Cu3(mpyba)2(2-apyma)(H2O)7]·8.3H2O (1), [Sr2Cu3(mpyba)2(2-apyma)(H2O)8]·11.6H2O (2) and [Sr4.5Cu4(mpyba)4(ox)(H2O)20]·8.5H2O (3) [H4mpyba = N,N'-2,6-pyridinebis(oxamic acid), 2-apyma = 2-(6-aminopyridinyl)Oxamate and ox = oxalate] have been synthesized and structurally characterized. Complexes 1 and 2 are isostructural compounds, with tricopper(ii) units having mpyba and its hydrolytic product (2-apyma) as ligands. They are interlinked through strontium(ii) (1) and calcium(ii) (2) ions to afford neutral two-dimensional networks. Two of the copper(ii) ions are five-coordinate in distorted square pyramidal (Cu3) and trigonal bipyramidal (Cu1) surroundings, whereas the other (Cu2) is six-coordinate in an elongated octahedral environment. The main difference between their structures, apart from the number of water molecules, resides in the nature of the alkaline earth cation coordinated to the Oxamate fragments, Sr2+ (1)/Ca2+ (2), which exhibit eight and seven coordination, respectively. The π-π interactions and an extensive network of hydrogen bonds in 1 and 2 lead to supramolecular 3D structures. The relatively small size of their cavities, in the micropore domain, hinders the inclusion of N2 but allows CO2 adsorption (0.45 and 0.52 mmol g-1 for 1 and 2, respectively). The structure of 3 is made up of [3,3] metallacyclophane-type motifs, having the formula [Cu2(mpyba)2(H2O)2]4-. These act as tetrakis(bidentate) ligands towards the strontium(ii) ions (Sr1, Sr2 and Sr3), leading to a sheet-like polymer growing in the bc plane, which extends further along the crystallographic a axis by a bis(chelating) oxalate between the Sr1 atoms. The investigation of the magnetic properties of 1-3 in the temperature range 1.9-300 K shows the occurrence of an overall antiferromagnetic behaviour for 1 and 2 [J12 = J23 = -9.71(2) (1) and -10.81(5) cm-1 (2), with the Hamiltonian being defined as H = -J12S1·S2 - J23S2·S3 + gβH[S1 + S2 + S3], and a ferromagnetic coupling within the dicopper(ii) metallacylophane unit of 3 [J = +1.86(1) cm-1 through the Hamiltonian H = -JS1·S2 + gβH(S1 + S2)]. Simple orbital symmetry considerations (1-3) and the spin polarization mechanism (3) account for the observed magnetic properties.

  • A Two-Dimensional Oxamate- and Oxalate-Bridged CuIIMnII Motif: Crystal Structure and Magnetic Properties of (Bu4N)2[Mn2{Cu(opba)}2ox]
    2016
    Co-Authors: Maria V. Marinho, Marcos A Ribeiro, Flavia C Machado, Carlos B Pinheiro, Humberto O Stumpf, Joan Cano, Francesc Lloret, Tatiana R. G. Simões, Cynthia L. M. Pereira, Miguel Julve
    Abstract:

    A new compound of formula (Bu4N)2[Mn2{Cu­(opba)}2ox] (1) [Bu4N+ = tetra-n-butylammonium cation, H4opba = 1,2-phenylenebis­(oxamic acid), and H2ox = oxalic acid] has been synthesized and magneto-structurally investigated. The reaction of manganese­(II) acetate, [Cu­(opba)]2–, and ox2– in dimethyl sulfoxide yielded single crystals of 1. The structure of 1 consists of heterobimetallic oxamato-bridged CuIIMnII chains which are connected through bis-bidentate oxalate coordinated to the manganese­(II) ions to afford anionic heterobimetallic layers of 63-hcb net topology. The layers are interleaved by n-Bu4N+ counterions. Each copper­(II) ion in 1 is four-coordinate in a square planar environment defined by two amidate-nitrogen and two carboxylate-oxygen atoms from the two Oxamate groups of the obpa ligand. The manganese­(II) ion is six-coordinate in a somewhat distorted octahedral surrounding that is built by two oxalate-oxygen and four carbonyl-oxygen atoms from two [Cu­(opba)]2– units. The magnetic properties of 1 in the temperature range 1.9–300 K correspond to those expected for the coexistence of intralayer antiferromagnetic interactions of the type copper­(II)–manganese­(II) across oxamato and manganese­(II)–manganese­(II) through oxalato bridges plus a weak spin canting in the very low temperature domain. Simulation of the magnetic data through quantum Monte Carlo methodology reveals the magnitude of the intralayer magnetic interactions [JCuMn = −32.5(3) cm–1, and JMnMn = −2.7(3) cm–1], their values being within the range of those previously observed in lower nuclearity systems

  • Crystal Engineering Applied to Modulate the Structure and Magnetic Properties of Oxamate Complexes Containing the [Cu(bpca)]+ Cation
    2016
    Co-Authors: Willian X. C. Oliveira, Miguel Julve, Carlos B Pinheiro, Francesc Lloret, Marinez M. Da Costa, Ana P. S. Fontes, Wallace C. Nunes, Cynthia L M Pereira
    Abstract:

    This work deals with the crystal engineering features of four related copper­(II)-based compounds with formulas {[{Cu­(bpca)}2­(H2ppba)]·1.33DMF­·0.66DMSO}n (2), [{Cu­(bpca)­(H2O)}2­(H2ppba)] (3), [{Cu­(bpca)}2­(H2ppba)]­·DMSO (4), and [{Cu­(bpca)}2­(H2ppba)]­·6H2O (5) [H4ppba = N,N′-1,4-phenylenebis­(oxamic acid) and Hbpca = bis­(2-pyridylcarbonyl)­amide] and how their distinct molecular and crystal structures translate into their different magnetic properties. 2 and 3 were obtained through the hydrolytic reaction of the double-stranded oxamato-based dipalladium­(II) paracyclophane precursor of formula [{K4(H2O)2}­{Pd2(ppba)2}] (1) with the mononuclear copper­(II) complex [Cu­(bpca)­(H2O)2]+, either in a water–DMSO–DMF solvent mixture or in water, respectively. The straightforward reaction of the neutral H4ppba molecule with [Cu­(bpca)­(H2O)2]+ in a water–DMSO mixture afforded compound 4, whereas compound 5 resulted from the reaction between the copper­(II) complex and the K2ppba salt in water. The [Pd2(ppba)2]4– tetraanionic unit which is present in 1 has a [3,3] metallacyclophane-type motif connected by two N–Pd–N bonds. This entity acts as a ligand toward partially hydrated potassium­(I) cations through its outer Oxamate oxygens leading to a neutral three-dimensional network. The structure of 2 consists of neutral chains made up of double oxo­(carboxylate-Oxamate)-bridged di­[{bis­(2-pyridylcarbonyl)­amidate}­copper­(II)] units are which connected by the extended H2ppba2– ligand, each of its Oxamate fragments adopting a bidentate/outer monodentate coordination mode. Compounds 2–5 are neutral and centrosymmetric dicopper­(II) complexes which have in common the presence of peripheral bpca ligands and H2ppba2– as a bridge with each of its monoprotonated Oxamate groups exhibiting rare monodentate (3) and bis-bidentate (4 and 5) coordination modes. Compounds 2, 4, and 5 share the same basic [{Cu­(bpca)}2­(H2ppba)] unit, but besides the difference in the cocrystallization solvent molecules and synthetic strategies, they feature very different crystal structures. To better understand the role of palladium­(II) ions in the formation of 2 and 3, some studies were carried out using different mixtures of solvents such as water, DMSO, and DMF which revealed a major importance of DMF in the formation of 2 and the dependence on the palladium­(II) ions in the formation of 3. A reaction pathway leading to the formation of 2 and 3 is then proposed. The variable-temperature (2.0–300 K) magnetic susceptibility measurements of 2, 4, and 5 revealed the occurrence of weak ferro- [J = +0.70 cm–1 (2)] and antiferromagnetic interactions [J = −0.90 (4) and −0.79 cm–1 (5)], the spin Hamiltonian being defined as H = −JS1·S2. The different nature and strength of the magnetic coupling along this unique series of compounds are discussed in the light of the structural data, and they are compared with those of related dicopper­(II) systems

  • bis n substituted Oxamate palladate ii complexes as effective catalysts for sustainable heck carbon carbon coupling reactions in n bu4nbr as the solvent
    Inorganic chemistry frontiers, 2015
    Co-Authors: Francisco R Forteaperez, Miguel Julve, Nadia Marino, Donatella Armentano, Giovanni De Munno, Berit Lisa Rothenpieler, Salah-eddine Stiriba
    Abstract:

    Five bis(oxamato)palladate(II) complexes of the formulae (n-Bu4N)2[Pd(4-Fpma)2] (1), (n-Bu4N)2[Pd(4-Clpma)2] (2), (n-Bu4N)2[Pd(4-Brpma)2] (3), (n-Bu4N)2[Pd(4-Brpma)2]·H2O (3a), (n-Bu4N)2[Pd(4-MeOpma)2] (4) and (n-Bu4N)2[Pd(4-Isopma)2] (5) (n-Bu4N+ = tetra-n-butylammonium, 4-Fpma = N-4-fluorophenylOxamate, 4-Clpma = N-4-chlorophenylOxamate, 4-Brpma = N-4-bromophenylOxamate, 4-MeOpma = N-4-methoxyphenylOxamate and 4-isopma = N-4-isopropylphenylOxamate) have been easily prepared and characterized by spectroscopic methods and the crystal structures of two of them (3a and 4) have been determined by single crystal X-ray diffraction. Each palladium(II) ion in 3a and 4 is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated Oxamate ligands building a centrosymmetric square planar PdN2O2 surrounding. The values of the Pd–N and Pd–O bond lengths vary in the ranges 2.034(3)–2.043(4) and 1.999(4)–2.013(3) A, respectively. The reduced bite of the chelating Oxamate ligands [81.3(2)–81.7(1) (3a) and 81.61(7)° (4)] is at the origin of the mean distortion of the ideal square environment. The catalytic role of compounds 1–5 as structurally well-defined precatalysts for the Heck-vinylation of a series of aryl iodide/bromide derivatives in n-Bu4NBr as a benign nonaqueous ionic liquid (i.d. molten salt) has been examined and compared with some commercially available palladium(II/0) complexes. From this study, it appears that the Oxamate-containing precatalysts 1–5 are not just ecologically benign, but also highly efficient, easily recoverable and reusable at least eight times without any relevant loss of catalytic activity or leaching from the ionic liquid medium.

  • Bis(N-substituted Oxamate)palladate(II) complexes as effective catalysts for sustainable Heck carbon–carbon coupling reactions in n-Bu4NBr as the solvent
    Inorganic Chemistry Frontiers, 2015
    Co-Authors: Francisco R. Fortea-pérez, Miguel Julve, Nadia Marino, Donatella Armentano, Giovanni De Munno, Berit Lisa Rothenpieler, Salah-eddine Stiriba
    Abstract:

    Five bis(oxamato)palladate(II) complexes of the formulae (n-Bu4N)2[Pd(4-Fpma)2] (1), (n-Bu4N)2[Pd(4-Clpma)2] (2), (n-Bu4N)2[Pd(4-Brpma)2] (3), (n-Bu4N)2[Pd(4-Brpma)2]·H2O (3a), (n-Bu4N)2[Pd(4-MeOpma)2] (4) and (n-Bu4N)2[Pd(4-Isopma)2] (5) (n-Bu4N+ = tetra-n-butylammonium, 4-Fpma = N-4-fluorophenylOxamate, 4-Clpma = N-4-chlorophenylOxamate, 4-Brpma = N-4-bromophenylOxamate, 4-MeOpma = N-4-methoxyphenylOxamate and 4-isopma = N-4-isopropylphenylOxamate) have been easily prepared and characterized by spectroscopic methods and the crystal structures of two of them (3a and 4) have been determined by single crystal X-ray diffraction. Each palladium(II) ion in 3a and 4 is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated Oxamate ligands building a centrosymmetric square planar PdN2O2 surrounding. The values of the Pd–N and Pd–O bond lengths vary in the ranges 2.034(3)–2.043(4) and 1.999(4)–2.013(3) A, respectively. The reduced bite of the chelating Oxamate ligands [81.3(2)–81.7(1) (3a) and 81.61(7)° (4)] is at the origin of the mean distortion of the ideal square environment. The catalytic role of compounds 1–5 as structurally well-defined precatalysts for the Heck-vinylation of a series of aryl iodide/bromide derivatives in n-Bu4NBr as a benign nonaqueous ionic liquid (i.d. molten salt) has been examined and compared with some commercially available palladium(II/0) complexes. From this study, it appears that the Oxamate-containing precatalysts 1–5 are not just ecologically benign, but also highly efficient, easily recoverable and reusable at least eight times without any relevant loss of catalytic activity or leaching from the ionic liquid medium.

Tatiana R G Simoes - One of the best experts on this subject based on the ideXlab platform.

  • dinuclear copper ii complexes containing Oxamate and blocking ligands crystal structure magnetic properties and dft calculations
    New Journal of Chemistry, 2020
    Co-Authors: Tatiana R G Simoes, Marcos A Ribeiro, Carlos B Pinheiro, Walace Do D Pim, Karina C Metz, Daniel C A Valente, Thiago Messias Cardozo, Emerson F Pedroso, Bruno A C Horta, Cynthia L M Pereira
    Abstract:

    Three dinuclear copper(II) complexes containing Oxamate-based ligands with the chemical formula [Cu(opba)Cu(dap)(H2O)]·H2O (1), [Cu(opba)Cu(dap-OH)(H2O)]·1.5H2O (2), and [Cu(opba)Cu(en)(H2O)]·4H2O (3) in which opba = o-phenylenebis(oxamato), dap = 1,3-diaminopropane, dap-OH = 2-hydroxy-1,3-diaminopropane and en = ethylenediamine have been synthesized and their crystal structures have been determined by single crystal X-ray diffraction. The molecular structures of 1–3 consist of neutral dicopper(II) complexes obtained by the “complex as a ligand” strategy, in which each [Cu(opba)]2− fragment acts as a bidentate ligand towards the copper(II) ion bonded to the amine capping ligands (dap, dap-OH and en) and the two other carbonyl groups are uncoordinated. Variable-temperature magnetic susceptibility measurements of 1–3 in the temperature range of 4–300 K reveal a strong antiferromagnetic coupling between the metal centers through the Oxamate bridge with J = −183.5 cm−1 (1), J = −195.8 cm−1 (2), and J = −195.6 cm−1 (3). The fit of the variable-temperature magnetic susceptibility data of 3 revealed that CuIICuII⋯CuIICuII coupling between the dinuclear entities is very weak. In all cases, the Hamiltonian used was H = −JS1·S2. DFT calculations based on the broken-symmetry formalism were used to provide further insight and an explanation for the reported behavior.

  • Characterization of compounds derived from copper-Oxamate and imidazolium by X-ray absorption and vibrational spectroscopies.
    Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2015
    Co-Authors: Gustavo M. Do Nascimento, Tatiana R G Simoes, Daniella O. Reis, Walace D. Do Pim, Noriberto A. Pradie, Humberto O Stumpf
    Abstract:

    In this work, compounds derived from copper-Oxamate anions (ortho, meta, and para)-phenylenebis (Oxamate) and imidazolium cations (1-butyl-3-methylimidazolium) were synthesized. The compounds were characterized by Raman and FTIR spectroscopies and the band assignments were supported by DFT calculations. Strong IR bands from 1610 to 1700cm(-1) dominated the spectra of the complex and can be assigned to νCO vibrations of the [Cu(opba)](2-) anions by the comparison with the DFT data. In opposition to the FTIR spectra, the main vibrational bands in the Raman spectra are observed in the 1350-1600cm(-1) range. All bands in this region are associated to the modified benzene vibrations of the copper-phenylenebis(Oxamate) anions. X-ray absorption near edge (XANES) at different energies (NK and Cu L2,3 edges) was also used to probe the interionic interactions. XANES data show that anion-cation interaction in the Cu-Oxamate-imidazolium changes the electronic structure around the CuN sites in the Oxamate anion.

  • a two dimensional Oxamate and oxalate bridged cu ii mn ii motif crystal structure and magnetic properties of bu4n 2 mn2 cu opba 2ox
    Inorganic Chemistry, 2013
    Co-Authors: Maria Vanda Marinho, Tatiana R G Simoes, Marcos A Ribeiro, Cynthia L M Pereira, Flavia C Machado, Carlos B Pinheiro, Humberto O Stumpf, Joan Cano, Francesc Lloret, Miguel Julve
    Abstract:

    A new compound of formula (Bu4N)2[Mn2{Cu(opba)}2ox] (1) [Bu4N(+) = tetra-n-butylammonium cation, H4opba = 1,2-phenylenebis(oxamic acid), and H2ox = oxalic acid] has been synthesized and magneto-structurally investigated. The reaction of manganese(II) acetate, [Cu(opba)](2-), and ox(2-) in dimethyl sulfoxide yielded single crystals of 1. The structure of 1 consists of heterobimetallic oxamato-bridged Cu(II)Mn(II) chains which are connected through bis-bidentate oxalate coordinated to the manganese(II) ions to afford anionic heterobimetallic layers of 6(3)-hcb net topology. The layers are interleaved by n-Bu4N(+) counterions. Each copper(II) ion in 1 is four-coordinate in a square planar environment defined by two amidate-nitrogen and two carboxylate-oxygen atoms from the two Oxamate groups of the obpa ligand. The manganese(II) ion is six-coordinate in a somewhat distorted octahedral surrounding that is built by two oxalate-oxygen and four carbonyl-oxygen atoms from two [Cu(opba)](2-) units. The magnetic properties of 1 in the temperature range 1.9-300 K correspond to those expected for the coexistence of intralayer antiferromagnetic interactions of the type copper(II)-manganese(II) across oxamato and manganese(II)-manganese(II) through oxalato bridges plus a weak spin canting in the very low temperature domain. Simulation of the magnetic data through quantum Monte Carlo methodology reveals the magnitude of the intralayer magnetic interactions [J(CuMn) = -32.5(3) cm(-1), and J(MnMn) = -2.7(3) cm(-1)], their values being within the range of those previously observed in lower nuclearity systems.

  • Copper(II) assembling with bis(2-pyridylcarbonyl)amidate and N,N′-2,2-phenylenebis(Oxamate)
    Dalton transactions (Cambridge England : 2003), 2013
    Co-Authors: Tatiana R G Simoes, Maria Vanda Marinho, Marcos A Ribeiro, Carlos B Pinheiro, Jesús Ferrando-soria, Raquel V. Mambrini, Daniella O. Reis, Mariadel Déniz, Catalina Ruiz-pérez, Danielle Cangussu
    Abstract:

    We herein present the synthesis and X-ray structures of five copper(II) complexes of formulae [Cu(bpca)(CF3SO3)(H2O)]·H2O (1), [Cu(bpca)(Phpr)(H2O)]·3/2H2O (2), {[Cu(bpca)]2[Cu(opba)(H2O)]}·H2O (3), {[Cu(bpca)]2(H2opba)}2·6H2O (4) and [Cu(bpca)(EtH2opba)]n (5), where bpca = bis(2-pyridylcarbonyl)amidate, Phpr = 3-phenylpropionate, CF3SO3− = triflate (anion of the trifluoromethanesulphonic acid), H4opba = N,N′-1,2-phenylenebis(oxamic acid), and EtH3opba = monoethyl ester derivative of the H4opba. 1 and 2 are mononuclear copper(II) complexes where the copper atom is five-coordinate in distorted square pyramidal surroundings with a tridentate bpca and a water molecule (1)/carboxylate oxygen (2) building the basal plane and a triflate oxygen (1)/water molecule (2) filling the apical position. 3 is a neutral tricopper(II) complex where the [Cu(opba)(H2O)]2− unit acts as a bis-bidentate ligand toward two peripheral [Cu(bpca)]+ fragments. The three crystallographically independent copper(II) ions in 3 are five-coordinate with two nitrogen and two oxygen atoms (inner copper atom)/three bpca-nitrogen and an Oxamate oxygen (outer copper atom) building the basal plane plus a water molecule (inner copper)/an Oxamate oxygen (outer copper) in the apical position (inner copper atom) of somewhat distorted square pyramidal surroundings. 4 is a centrosymmetric tetracopper(II) compound where four [Cu(bpca)]+ fragments are assembled by two H2opba2− groups adopting an unusual bidentate/bis-monodentate bridging mode. The two crystallographically independent copper(II) ions in 4 are also five-coordinate having the three bpca-nitrogens in basal positions, the other two sites of the distorted square pyramid being filled by two oxygens of either a bidentate Oxamate (at one copper centre) or two bis-monodentate Oxamates (at the other copper atom). 5 is a zigzag chain of [Cu(bpca)(H2O)]+ units which are connected through the EtH2opba− ligand adopting a bidentate/monodentate bridging mode across the monodeprotonated Oxamate group. Each copper(II) ion in 5 is six-coordinate in an elongated octahedral CuN3O3 chromophore. The magnetic properties of 3–5 were investigated in the temperature range 1.9–300 K. 3 exhibits an intermediate intramolecular antiferromagnetic interaction [J = −65.8(2) cm−1 with the Hamiltonian H = −J(SCu1·SCu2 + SCu2·SCu3)] which leads to a low-lying spin doublet at low temperatures. A weak antiferromagnetic coupling between the inner copper(II) ions occurs in 4 [J = −2.36(2) cm−1, H = −JS1·S2)] and a very small intrachain antiferromagnetic interaction is observed in 5 [J = −0.17(1) cm−1 with H = −J∑iSi·Si+1]. These values are analyzed by means of simple orbital symmetry considerations and compared with those previously reported for parent systems.

  • copper ii assembling with bis 2 pyridylcarbonyl amidate and n n 2 2 phenylenebis Oxamate
    Dalton Transactions, 2013
    Co-Authors: Tatiana R G Simoes, Maria Vanda Marinho, Marcos A Ribeiro, Carlos B Pinheiro, Raquel V. Mambrini, Daniella O. Reis, Mariadel Déniz, Jesus Ferrandosoria, Catalina Ruizperez, Danielle Cangussu
    Abstract:

    We herein present the synthesis and X-ray structures of five copper(II) complexes of formulae [Cu(bpca)(CF3SO3)(H2O)]·H2O (1), [Cu(bpca)(Phpr)(H2O)]·3/2H2O (2), {[Cu(bpca)]2[Cu(opba)(H2O)]}·H2O (3), {[Cu(bpca)]2(H2opba)}2·6H2O (4) and [Cu(bpca)(EtH2opba)]n (5), where bpca = bis(2-pyridylcarbonyl)amidate, Phpr = 3-phenylpropionate, CF3SO3− = triflate (anion of the trifluoromethanesulphonic acid), H4opba = N,N′-1,2-phenylenebis(oxamic acid), and EtH3opba = monoethyl ester derivative of the H4opba. 1 and 2 are mononuclear copper(II) complexes where the copper atom is five-coordinate in distorted square pyramidal surroundings with a tridentate bpca and a water molecule (1)/carboxylate oxygen (2) building the basal plane and a triflate oxygen (1)/water molecule (2) filling the apical position. 3 is a neutral tricopper(II) complex where the [Cu(opba)(H2O)]2− unit acts as a bis-bidentate ligand toward two peripheral [Cu(bpca)]+ fragments. The three crystallographically independent copper(II) ions in 3 are five-coordinate with two nitrogen and two oxygen atoms (inner copper atom)/three bpca-nitrogen and an Oxamate oxygen (outer copper atom) building the basal plane plus a water molecule (inner copper)/an Oxamate oxygen (outer copper) in the apical position (inner copper atom) of somewhat distorted square pyramidal surroundings. 4 is a centrosymmetric tetracopper(II) compound where four [Cu(bpca)]+ fragments are assembled by two H2opba2− groups adopting an unusual bidentate/bis-monodentate bridging mode. The two crystallographically independent copper(II) ions in 4 are also five-coordinate having the three bpca-nitrogens in basal positions, the other two sites of the distorted square pyramid being filled by two oxygens of either a bidentate Oxamate (at one copper centre) or two bis-monodentate Oxamates (at the other copper atom). 5 is a zigzag chain of [Cu(bpca)(H2O)]+ units which are connected through the EtH2opba− ligand adopting a bidentate/monodentate bridging mode across the monodeprotonated Oxamate group. Each copper(II) ion in 5 is six-coordinate in an elongated octahedral CuN3O3 chromophore. The magnetic properties of 3–5 were investigated in the temperature range 1.9–300 K. 3 exhibits an intermediate intramolecular antiferromagnetic interaction [J = −65.8(2) cm−1 with the Hamiltonian H = −J(SCu1·SCu2 + SCu2·SCu3)] which leads to a low-lying spin doublet at low temperatures. A weak antiferromagnetic coupling between the inner copper(II) ions occurs in 4 [J = −2.36(2) cm−1, H = −JS1·S2)] and a very small intrachain antiferromagnetic interaction is observed in 5 [J = −0.17(1) cm−1 with H = −J∑iSi·Si+1]. These values are analyzed by means of simple orbital symmetry considerations and compared with those previously reported for parent systems.

Cynthia L M Pereira - One of the best experts on this subject based on the ideXlab platform.

  • Ferromagnetic coupling in a dicopper(ii) Oxamate complex bridged by carboxylate groups
    CrystEngComm, 2021
    Co-Authors: Tamyris T. Da Cunha, Emerson F Pedroso, Cleverton O. C. Da Silveira, Vitor M. M. Barbosa, Willian X. C. Oliveira, Eufrânio N. Da Silva Júnior, Fabio Furlan Ferreira, Cynthia L M Pereira
    Abstract:

    The self-assembly of N-(4-hydroxyphenyl)Oxamate ligands and copper(ii) ions result in a dinuclear copper complex bridged by carboxylate moieties of the Oxamate ligands exhibiting a ferromagnetic coupling.

  • dinuclear copper ii complexes containing Oxamate and blocking ligands crystal structure magnetic properties and dft calculations
    New Journal of Chemistry, 2020
    Co-Authors: Tatiana R G Simoes, Marcos A Ribeiro, Carlos B Pinheiro, Walace Do D Pim, Karina C Metz, Daniel C A Valente, Thiago Messias Cardozo, Emerson F Pedroso, Bruno A C Horta, Cynthia L M Pereira
    Abstract:

    Three dinuclear copper(II) complexes containing Oxamate-based ligands with the chemical formula [Cu(opba)Cu(dap)(H2O)]·H2O (1), [Cu(opba)Cu(dap-OH)(H2O)]·1.5H2O (2), and [Cu(opba)Cu(en)(H2O)]·4H2O (3) in which opba = o-phenylenebis(oxamato), dap = 1,3-diaminopropane, dap-OH = 2-hydroxy-1,3-diaminopropane and en = ethylenediamine have been synthesized and their crystal structures have been determined by single crystal X-ray diffraction. The molecular structures of 1–3 consist of neutral dicopper(II) complexes obtained by the “complex as a ligand” strategy, in which each [Cu(opba)]2− fragment acts as a bidentate ligand towards the copper(II) ion bonded to the amine capping ligands (dap, dap-OH and en) and the two other carbonyl groups are uncoordinated. Variable-temperature magnetic susceptibility measurements of 1–3 in the temperature range of 4–300 K reveal a strong antiferromagnetic coupling between the metal centers through the Oxamate bridge with J = −183.5 cm−1 (1), J = −195.8 cm−1 (2), and J = −195.6 cm−1 (3). The fit of the variable-temperature magnetic susceptibility data of 3 revealed that CuIICuII⋯CuIICuII coupling between the dinuclear entities is very weak. In all cases, the Hamiltonian used was H = −JS1·S2. DFT calculations based on the broken-symmetry formalism were used to provide further insight and an explanation for the reported behavior.

  • Crystal Engineering Applied to Modulate the Structure and Magnetic Properties of Oxamate Complexes Containing the [Cu(bpca)]+ Cation
    2016
    Co-Authors: Willian X. C. Oliveira, Miguel Julve, Carlos B Pinheiro, Francesc Lloret, Marinez M. Da Costa, Ana P. S. Fontes, Wallace C. Nunes, Cynthia L M Pereira
    Abstract:

    This work deals with the crystal engineering features of four related copper­(II)-based compounds with formulas {[{Cu­(bpca)}2­(H2ppba)]·1.33DMF­·0.66DMSO}n (2), [{Cu­(bpca)­(H2O)}2­(H2ppba)] (3), [{Cu­(bpca)}2­(H2ppba)]­·DMSO (4), and [{Cu­(bpca)}2­(H2ppba)]­·6H2O (5) [H4ppba = N,N′-1,4-phenylenebis­(oxamic acid) and Hbpca = bis­(2-pyridylcarbonyl)­amide] and how their distinct molecular and crystal structures translate into their different magnetic properties. 2 and 3 were obtained through the hydrolytic reaction of the double-stranded oxamato-based dipalladium­(II) paracyclophane precursor of formula [{K4(H2O)2}­{Pd2(ppba)2}] (1) with the mononuclear copper­(II) complex [Cu­(bpca)­(H2O)2]+, either in a water–DMSO–DMF solvent mixture or in water, respectively. The straightforward reaction of the neutral H4ppba molecule with [Cu­(bpca)­(H2O)2]+ in a water–DMSO mixture afforded compound 4, whereas compound 5 resulted from the reaction between the copper­(II) complex and the K2ppba salt in water. The [Pd2(ppba)2]4– tetraanionic unit which is present in 1 has a [3,3] metallacyclophane-type motif connected by two N–Pd–N bonds. This entity acts as a ligand toward partially hydrated potassium­(I) cations through its outer Oxamate oxygens leading to a neutral three-dimensional network. The structure of 2 consists of neutral chains made up of double oxo­(carboxylate-Oxamate)-bridged di­[{bis­(2-pyridylcarbonyl)­amidate}­copper­(II)] units are which connected by the extended H2ppba2– ligand, each of its Oxamate fragments adopting a bidentate/outer monodentate coordination mode. Compounds 2–5 are neutral and centrosymmetric dicopper­(II) complexes which have in common the presence of peripheral bpca ligands and H2ppba2– as a bridge with each of its monoprotonated Oxamate groups exhibiting rare monodentate (3) and bis-bidentate (4 and 5) coordination modes. Compounds 2, 4, and 5 share the same basic [{Cu­(bpca)}2­(H2ppba)] unit, but besides the difference in the cocrystallization solvent molecules and synthetic strategies, they feature very different crystal structures. To better understand the role of palladium­(II) ions in the formation of 2 and 3, some studies were carried out using different mixtures of solvents such as water, DMSO, and DMF which revealed a major importance of DMF in the formation of 2 and the dependence on the palladium­(II) ions in the formation of 3. A reaction pathway leading to the formation of 2 and 3 is then proposed. The variable-temperature (2.0–300 K) magnetic susceptibility measurements of 2, 4, and 5 revealed the occurrence of weak ferro- [J = +0.70 cm–1 (2)] and antiferromagnetic interactions [J = −0.90 (4) and −0.79 cm–1 (5)], the spin Hamiltonian being defined as H = −JS1·S2. The different nature and strength of the magnetic coupling along this unique series of compounds are discussed in the light of the structural data, and they are compared with those of related dicopper­(II) systems

  • a two dimensional Oxamate and oxalate bridged cu ii mn ii motif crystal structure and magnetic properties of bu4n 2 mn2 cu opba 2ox
    Inorganic Chemistry, 2013
    Co-Authors: Maria Vanda Marinho, Tatiana R G Simoes, Marcos A Ribeiro, Cynthia L M Pereira, Flavia C Machado, Carlos B Pinheiro, Humberto O Stumpf, Joan Cano, Francesc Lloret, Miguel Julve
    Abstract:

    A new compound of formula (Bu4N)2[Mn2{Cu(opba)}2ox] (1) [Bu4N(+) = tetra-n-butylammonium cation, H4opba = 1,2-phenylenebis(oxamic acid), and H2ox = oxalic acid] has been synthesized and magneto-structurally investigated. The reaction of manganese(II) acetate, [Cu(opba)](2-), and ox(2-) in dimethyl sulfoxide yielded single crystals of 1. The structure of 1 consists of heterobimetallic oxamato-bridged Cu(II)Mn(II) chains which are connected through bis-bidentate oxalate coordinated to the manganese(II) ions to afford anionic heterobimetallic layers of 6(3)-hcb net topology. The layers are interleaved by n-Bu4N(+) counterions. Each copper(II) ion in 1 is four-coordinate in a square planar environment defined by two amidate-nitrogen and two carboxylate-oxygen atoms from the two Oxamate groups of the obpa ligand. The manganese(II) ion is six-coordinate in a somewhat distorted octahedral surrounding that is built by two oxalate-oxygen and four carbonyl-oxygen atoms from two [Cu(opba)](2-) units. The magnetic properties of 1 in the temperature range 1.9-300 K correspond to those expected for the coexistence of intralayer antiferromagnetic interactions of the type copper(II)-manganese(II) across oxamato and manganese(II)-manganese(II) through oxalato bridges plus a weak spin canting in the very low temperature domain. Simulation of the magnetic data through quantum Monte Carlo methodology reveals the magnitude of the intralayer magnetic interactions [J(CuMn) = -32.5(3) cm(-1), and J(MnMn) = -2.7(3) cm(-1)], their values being within the range of those previously observed in lower nuclearity systems.

Carlos B Pinheiro - One of the best experts on this subject based on the ideXlab platform.

  • dinuclear copper ii complexes containing Oxamate and blocking ligands crystal structure magnetic properties and dft calculations
    New Journal of Chemistry, 2020
    Co-Authors: Tatiana R G Simoes, Marcos A Ribeiro, Carlos B Pinheiro, Walace Do D Pim, Karina C Metz, Daniel C A Valente, Thiago Messias Cardozo, Emerson F Pedroso, Bruno A C Horta, Cynthia L M Pereira
    Abstract:

    Three dinuclear copper(II) complexes containing Oxamate-based ligands with the chemical formula [Cu(opba)Cu(dap)(H2O)]·H2O (1), [Cu(opba)Cu(dap-OH)(H2O)]·1.5H2O (2), and [Cu(opba)Cu(en)(H2O)]·4H2O (3) in which opba = o-phenylenebis(oxamato), dap = 1,3-diaminopropane, dap-OH = 2-hydroxy-1,3-diaminopropane and en = ethylenediamine have been synthesized and their crystal structures have been determined by single crystal X-ray diffraction. The molecular structures of 1–3 consist of neutral dicopper(II) complexes obtained by the “complex as a ligand” strategy, in which each [Cu(opba)]2− fragment acts as a bidentate ligand towards the copper(II) ion bonded to the amine capping ligands (dap, dap-OH and en) and the two other carbonyl groups are uncoordinated. Variable-temperature magnetic susceptibility measurements of 1–3 in the temperature range of 4–300 K reveal a strong antiferromagnetic coupling between the metal centers through the Oxamate bridge with J = −183.5 cm−1 (1), J = −195.8 cm−1 (2), and J = −195.6 cm−1 (3). The fit of the variable-temperature magnetic susceptibility data of 3 revealed that CuIICuII⋯CuIICuII coupling between the dinuclear entities is very weak. In all cases, the Hamiltonian used was H = −JS1·S2. DFT calculations based on the broken-symmetry formalism were used to provide further insight and an explanation for the reported behavior.

  • A Two-Dimensional Oxamate- and Oxalate-Bridged CuIIMnII Motif: Crystal Structure and Magnetic Properties of (Bu4N)2[Mn2{Cu(opba)}2ox]
    2016
    Co-Authors: Maria V. Marinho, Marcos A Ribeiro, Flavia C Machado, Carlos B Pinheiro, Humberto O Stumpf, Joan Cano, Francesc Lloret, Tatiana R. G. Simões, Cynthia L. M. Pereira, Miguel Julve
    Abstract:

    A new compound of formula (Bu4N)2[Mn2{Cu­(opba)}2ox] (1) [Bu4N+ = tetra-n-butylammonium cation, H4opba = 1,2-phenylenebis­(oxamic acid), and H2ox = oxalic acid] has been synthesized and magneto-structurally investigated. The reaction of manganese­(II) acetate, [Cu­(opba)]2–, and ox2– in dimethyl sulfoxide yielded single crystals of 1. The structure of 1 consists of heterobimetallic oxamato-bridged CuIIMnII chains which are connected through bis-bidentate oxalate coordinated to the manganese­(II) ions to afford anionic heterobimetallic layers of 63-hcb net topology. The layers are interleaved by n-Bu4N+ counterions. Each copper­(II) ion in 1 is four-coordinate in a square planar environment defined by two amidate-nitrogen and two carboxylate-oxygen atoms from the two Oxamate groups of the obpa ligand. The manganese­(II) ion is six-coordinate in a somewhat distorted octahedral surrounding that is built by two oxalate-oxygen and four carbonyl-oxygen atoms from two [Cu­(opba)]2– units. The magnetic properties of 1 in the temperature range 1.9–300 K correspond to those expected for the coexistence of intralayer antiferromagnetic interactions of the type copper­(II)–manganese­(II) across oxamato and manganese­(II)–manganese­(II) through oxalato bridges plus a weak spin canting in the very low temperature domain. Simulation of the magnetic data through quantum Monte Carlo methodology reveals the magnitude of the intralayer magnetic interactions [JCuMn = −32.5(3) cm–1, and JMnMn = −2.7(3) cm–1], their values being within the range of those previously observed in lower nuclearity systems

  • Crystal Engineering Applied to Modulate the Structure and Magnetic Properties of Oxamate Complexes Containing the [Cu(bpca)]+ Cation
    2016
    Co-Authors: Willian X. C. Oliveira, Miguel Julve, Carlos B Pinheiro, Francesc Lloret, Marinez M. Da Costa, Ana P. S. Fontes, Wallace C. Nunes, Cynthia L M Pereira
    Abstract:

    This work deals with the crystal engineering features of four related copper­(II)-based compounds with formulas {[{Cu­(bpca)}2­(H2ppba)]·1.33DMF­·0.66DMSO}n (2), [{Cu­(bpca)­(H2O)}2­(H2ppba)] (3), [{Cu­(bpca)}2­(H2ppba)]­·DMSO (4), and [{Cu­(bpca)}2­(H2ppba)]­·6H2O (5) [H4ppba = N,N′-1,4-phenylenebis­(oxamic acid) and Hbpca = bis­(2-pyridylcarbonyl)­amide] and how their distinct molecular and crystal structures translate into their different magnetic properties. 2 and 3 were obtained through the hydrolytic reaction of the double-stranded oxamato-based dipalladium­(II) paracyclophane precursor of formula [{K4(H2O)2}­{Pd2(ppba)2}] (1) with the mononuclear copper­(II) complex [Cu­(bpca)­(H2O)2]+, either in a water–DMSO–DMF solvent mixture or in water, respectively. The straightforward reaction of the neutral H4ppba molecule with [Cu­(bpca)­(H2O)2]+ in a water–DMSO mixture afforded compound 4, whereas compound 5 resulted from the reaction between the copper­(II) complex and the K2ppba salt in water. The [Pd2(ppba)2]4– tetraanionic unit which is present in 1 has a [3,3] metallacyclophane-type motif connected by two N–Pd–N bonds. This entity acts as a ligand toward partially hydrated potassium­(I) cations through its outer Oxamate oxygens leading to a neutral three-dimensional network. The structure of 2 consists of neutral chains made up of double oxo­(carboxylate-Oxamate)-bridged di­[{bis­(2-pyridylcarbonyl)­amidate}­copper­(II)] units are which connected by the extended H2ppba2– ligand, each of its Oxamate fragments adopting a bidentate/outer monodentate coordination mode. Compounds 2–5 are neutral and centrosymmetric dicopper­(II) complexes which have in common the presence of peripheral bpca ligands and H2ppba2– as a bridge with each of its monoprotonated Oxamate groups exhibiting rare monodentate (3) and bis-bidentate (4 and 5) coordination modes. Compounds 2, 4, and 5 share the same basic [{Cu­(bpca)}2­(H2ppba)] unit, but besides the difference in the cocrystallization solvent molecules and synthetic strategies, they feature very different crystal structures. To better understand the role of palladium­(II) ions in the formation of 2 and 3, some studies were carried out using different mixtures of solvents such as water, DMSO, and DMF which revealed a major importance of DMF in the formation of 2 and the dependence on the palladium­(II) ions in the formation of 3. A reaction pathway leading to the formation of 2 and 3 is then proposed. The variable-temperature (2.0–300 K) magnetic susceptibility measurements of 2, 4, and 5 revealed the occurrence of weak ferro- [J = +0.70 cm–1 (2)] and antiferromagnetic interactions [J = −0.90 (4) and −0.79 cm–1 (5)], the spin Hamiltonian being defined as H = −JS1·S2. The different nature and strength of the magnetic coupling along this unique series of compounds are discussed in the light of the structural data, and they are compared with those of related dicopper­(II) systems

  • a two dimensional Oxamate and oxalate bridged cu ii mn ii motif crystal structure and magnetic properties of bu4n 2 mn2 cu opba 2ox
    Inorganic Chemistry, 2013
    Co-Authors: Maria Vanda Marinho, Tatiana R G Simoes, Marcos A Ribeiro, Cynthia L M Pereira, Flavia C Machado, Carlos B Pinheiro, Humberto O Stumpf, Joan Cano, Francesc Lloret, Miguel Julve
    Abstract:

    A new compound of formula (Bu4N)2[Mn2{Cu(opba)}2ox] (1) [Bu4N(+) = tetra-n-butylammonium cation, H4opba = 1,2-phenylenebis(oxamic acid), and H2ox = oxalic acid] has been synthesized and magneto-structurally investigated. The reaction of manganese(II) acetate, [Cu(opba)](2-), and ox(2-) in dimethyl sulfoxide yielded single crystals of 1. The structure of 1 consists of heterobimetallic oxamato-bridged Cu(II)Mn(II) chains which are connected through bis-bidentate oxalate coordinated to the manganese(II) ions to afford anionic heterobimetallic layers of 6(3)-hcb net topology. The layers are interleaved by n-Bu4N(+) counterions. Each copper(II) ion in 1 is four-coordinate in a square planar environment defined by two amidate-nitrogen and two carboxylate-oxygen atoms from the two Oxamate groups of the obpa ligand. The manganese(II) ion is six-coordinate in a somewhat distorted octahedral surrounding that is built by two oxalate-oxygen and four carbonyl-oxygen atoms from two [Cu(opba)](2-) units. The magnetic properties of 1 in the temperature range 1.9-300 K correspond to those expected for the coexistence of intralayer antiferromagnetic interactions of the type copper(II)-manganese(II) across oxamato and manganese(II)-manganese(II) through oxalato bridges plus a weak spin canting in the very low temperature domain. Simulation of the magnetic data through quantum Monte Carlo methodology reveals the magnitude of the intralayer magnetic interactions [J(CuMn) = -32.5(3) cm(-1), and J(MnMn) = -2.7(3) cm(-1)], their values being within the range of those previously observed in lower nuclearity systems.

  • Copper(II) assembling with bis(2-pyridylcarbonyl)amidate and N,N′-2,2-phenylenebis(Oxamate)
    Dalton transactions (Cambridge England : 2003), 2013
    Co-Authors: Tatiana R G Simoes, Maria Vanda Marinho, Marcos A Ribeiro, Carlos B Pinheiro, Jesús Ferrando-soria, Raquel V. Mambrini, Daniella O. Reis, Mariadel Déniz, Catalina Ruiz-pérez, Danielle Cangussu
    Abstract:

    We herein present the synthesis and X-ray structures of five copper(II) complexes of formulae [Cu(bpca)(CF3SO3)(H2O)]·H2O (1), [Cu(bpca)(Phpr)(H2O)]·3/2H2O (2), {[Cu(bpca)]2[Cu(opba)(H2O)]}·H2O (3), {[Cu(bpca)]2(H2opba)}2·6H2O (4) and [Cu(bpca)(EtH2opba)]n (5), where bpca = bis(2-pyridylcarbonyl)amidate, Phpr = 3-phenylpropionate, CF3SO3− = triflate (anion of the trifluoromethanesulphonic acid), H4opba = N,N′-1,2-phenylenebis(oxamic acid), and EtH3opba = monoethyl ester derivative of the H4opba. 1 and 2 are mononuclear copper(II) complexes where the copper atom is five-coordinate in distorted square pyramidal surroundings with a tridentate bpca and a water molecule (1)/carboxylate oxygen (2) building the basal plane and a triflate oxygen (1)/water molecule (2) filling the apical position. 3 is a neutral tricopper(II) complex where the [Cu(opba)(H2O)]2− unit acts as a bis-bidentate ligand toward two peripheral [Cu(bpca)]+ fragments. The three crystallographically independent copper(II) ions in 3 are five-coordinate with two nitrogen and two oxygen atoms (inner copper atom)/three bpca-nitrogen and an Oxamate oxygen (outer copper atom) building the basal plane plus a water molecule (inner copper)/an Oxamate oxygen (outer copper) in the apical position (inner copper atom) of somewhat distorted square pyramidal surroundings. 4 is a centrosymmetric tetracopper(II) compound where four [Cu(bpca)]+ fragments are assembled by two H2opba2− groups adopting an unusual bidentate/bis-monodentate bridging mode. The two crystallographically independent copper(II) ions in 4 are also five-coordinate having the three bpca-nitrogens in basal positions, the other two sites of the distorted square pyramid being filled by two oxygens of either a bidentate Oxamate (at one copper centre) or two bis-monodentate Oxamates (at the other copper atom). 5 is a zigzag chain of [Cu(bpca)(H2O)]+ units which are connected through the EtH2opba− ligand adopting a bidentate/monodentate bridging mode across the monodeprotonated Oxamate group. Each copper(II) ion in 5 is six-coordinate in an elongated octahedral CuN3O3 chromophore. The magnetic properties of 3–5 were investigated in the temperature range 1.9–300 K. 3 exhibits an intermediate intramolecular antiferromagnetic interaction [J = −65.8(2) cm−1 with the Hamiltonian H = −J(SCu1·SCu2 + SCu2·SCu3)] which leads to a low-lying spin doublet at low temperatures. A weak antiferromagnetic coupling between the inner copper(II) ions occurs in 4 [J = −2.36(2) cm−1, H = −JS1·S2)] and a very small intrachain antiferromagnetic interaction is observed in 5 [J = −0.17(1) cm−1 with H = −J∑iSi·Si+1]. These values are analyzed by means of simple orbital symmetry considerations and compared with those previously reported for parent systems.

Salah-eddine Stiriba - One of the best experts on this subject based on the ideXlab platform.

  • bis n substituted Oxamate palladate ii complexes as effective catalysts for sustainable heck carbon carbon coupling reactions in n bu4nbr as the solvent
    Inorganic chemistry frontiers, 2015
    Co-Authors: Francisco R Forteaperez, Miguel Julve, Nadia Marino, Donatella Armentano, Giovanni De Munno, Berit Lisa Rothenpieler, Salah-eddine Stiriba
    Abstract:

    Five bis(oxamato)palladate(II) complexes of the formulae (n-Bu4N)2[Pd(4-Fpma)2] (1), (n-Bu4N)2[Pd(4-Clpma)2] (2), (n-Bu4N)2[Pd(4-Brpma)2] (3), (n-Bu4N)2[Pd(4-Brpma)2]·H2O (3a), (n-Bu4N)2[Pd(4-MeOpma)2] (4) and (n-Bu4N)2[Pd(4-Isopma)2] (5) (n-Bu4N+ = tetra-n-butylammonium, 4-Fpma = N-4-fluorophenylOxamate, 4-Clpma = N-4-chlorophenylOxamate, 4-Brpma = N-4-bromophenylOxamate, 4-MeOpma = N-4-methoxyphenylOxamate and 4-isopma = N-4-isopropylphenylOxamate) have been easily prepared and characterized by spectroscopic methods and the crystal structures of two of them (3a and 4) have been determined by single crystal X-ray diffraction. Each palladium(II) ion in 3a and 4 is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated Oxamate ligands building a centrosymmetric square planar PdN2O2 surrounding. The values of the Pd–N and Pd–O bond lengths vary in the ranges 2.034(3)–2.043(4) and 1.999(4)–2.013(3) A, respectively. The reduced bite of the chelating Oxamate ligands [81.3(2)–81.7(1) (3a) and 81.61(7)° (4)] is at the origin of the mean distortion of the ideal square environment. The catalytic role of compounds 1–5 as structurally well-defined precatalysts for the Heck-vinylation of a series of aryl iodide/bromide derivatives in n-Bu4NBr as a benign nonaqueous ionic liquid (i.d. molten salt) has been examined and compared with some commercially available palladium(II/0) complexes. From this study, it appears that the Oxamate-containing precatalysts 1–5 are not just ecologically benign, but also highly efficient, easily recoverable and reusable at least eight times without any relevant loss of catalytic activity or leaching from the ionic liquid medium.

  • Bis(N-substituted Oxamate)palladate(II) complexes as effective catalysts for sustainable Heck carbon–carbon coupling reactions in n-Bu4NBr as the solvent
    Inorganic Chemistry Frontiers, 2015
    Co-Authors: Francisco R. Fortea-pérez, Miguel Julve, Nadia Marino, Donatella Armentano, Giovanni De Munno, Berit Lisa Rothenpieler, Salah-eddine Stiriba
    Abstract:

    Five bis(oxamato)palladate(II) complexes of the formulae (n-Bu4N)2[Pd(4-Fpma)2] (1), (n-Bu4N)2[Pd(4-Clpma)2] (2), (n-Bu4N)2[Pd(4-Brpma)2] (3), (n-Bu4N)2[Pd(4-Brpma)2]·H2O (3a), (n-Bu4N)2[Pd(4-MeOpma)2] (4) and (n-Bu4N)2[Pd(4-Isopma)2] (5) (n-Bu4N+ = tetra-n-butylammonium, 4-Fpma = N-4-fluorophenylOxamate, 4-Clpma = N-4-chlorophenylOxamate, 4-Brpma = N-4-bromophenylOxamate, 4-MeOpma = N-4-methoxyphenylOxamate and 4-isopma = N-4-isopropylphenylOxamate) have been easily prepared and characterized by spectroscopic methods and the crystal structures of two of them (3a and 4) have been determined by single crystal X-ray diffraction. Each palladium(II) ion in 3a and 4 is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated Oxamate ligands building a centrosymmetric square planar PdN2O2 surrounding. The values of the Pd–N and Pd–O bond lengths vary in the ranges 2.034(3)–2.043(4) and 1.999(4)–2.013(3) A, respectively. The reduced bite of the chelating Oxamate ligands [81.3(2)–81.7(1) (3a) and 81.61(7)° (4)] is at the origin of the mean distortion of the ideal square environment. The catalytic role of compounds 1–5 as structurally well-defined precatalysts for the Heck-vinylation of a series of aryl iodide/bromide derivatives in n-Bu4NBr as a benign nonaqueous ionic liquid (i.d. molten salt) has been examined and compared with some commercially available palladium(II/0) complexes. From this study, it appears that the Oxamate-containing precatalysts 1–5 are not just ecologically benign, but also highly efficient, easily recoverable and reusable at least eight times without any relevant loss of catalytic activity or leaching from the ionic liquid medium.

  • solid state cis trans isomerism in bis oxamato palladate ii complexes synthesis structural studies and catalytic activity
    CrystEngComm, 2014
    Co-Authors: Francisco R Forteaperez, Miguel Julve, Nadia Marino, Donatella Armentano, Giovanni De Munno, Salah-eddine Stiriba
    Abstract:

    A new generation of bis(oxamato)palladate(II) monomeric complexes has been prepared by using N-2,6-dimethylphenylOxamate (2,6-Me2pma) as the ligand. Four alkaline salts of the complex, namely {[Na(H2O)]2trans-[PdII(2,6-Me2pma)2]}n (1a), {[Na4(H2O)2]cis-[PdII(2,6-Me2pma)2]2}n (1b), {[K4(H2O)3]cis-[PdII(2,6-Me2pma)2]2}n (2), {[Rb4(H2O)3]cis-[PdII(2,6-Me2pma)2]2}n (3) and {[Cs6(H2O)7]trans-[PdII(2,6-Me2pma)2]2cis-[PdII(2,6-Me2pma)2]}n·3nH2O (4), were obtained and structurally characterized by single crystal X-ray diffraction. Both the cis and trans stereoisomers of the [PdII(2,6-Me2pma)2]2− complex anion were isolated in the solid state, in a cation-dependent manner. The trans-isomer as the sodium salt (1a) crystallizes in the monoclinic space group I2/a with half of the molecule in the asymmetric unit. The cis isomer as sodium (1b), potassium (2) or rubidium (3) salt crystallizes in the acentric monoclinic space group Cc, with two whole molecules in the asymmetric unit. In the presence of cesium(I) (4), both the cis and trans stereoisomers co-crystallize in the orthorhombic system with Pbca as the space group, with two whole and two half molecules in the asymmetric unit. Previously reported square-planar bis(oxamato)metallate(II) [M = Cu(II) or Pd(II)] species with similar N-aryl substituted Oxamate ligands only showed the occurrence of the trans isomer, complexes 1b and 2–4 offering unique examples of the alternative cis stereochemistry. The catalytic properties of 1a, 2–4 have been investigated in the palladium-catalyzed arylation of phenylboronic acid with a variety of aryl halides referred to as the Suzuki reaction, yielding biaryl compounds in very higher yields when iodobenzene [turnover number (TON) = 88–99 and turnover frequency (TOF) = 1056–1188 h−1] was used compared to commercial palladium(II) catalysts.

  • sustainable carbon carbon bond formation catalyzed by new Oxamate containing palladium ii complexes in ionic liquids
    Journal of Organometallic Chemistry, 2013
    Co-Authors: Francisco R Forteaperez, Miguel Julve, Donatella Armentano, Giovanni De Munno, Isabel Schlegel, Salah-eddine Stiriba
    Abstract:

    Abstract New and versatile bis(oxamato)palladate(II) complexes of formula ( n -Bu 4 N) 2 [Pd(2-Mepma) 2 ]·4H 2 O ( 1a ) and ( n -Bu 4 N) 2 [Pd(4-Mepma) 2 ]·2H 2 O·MeCN ( 1b ) ( n -Bu 4 N +  = tetra- n -buthylammonium, 2-Mepma =  N -2-methylphenylOxamate and 4-Mepma =  N -4-methylphenylOxamate) have been synthesized and characterized by spectroscopic methods and single crystal X-ray diffraction. Each palladium(II) ion in 1a and 1b is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated Oxamate ligands building a centrosymmetric square planar surrounding. Their catalytic role has been investigated for both Heck and Suzuki coupling reactions using a series of aryl iodide/bromide derivatives in tetra- n -butylammonium bromide ( n -Bu 4 NBr) as ionic liquid, i.e. molten salt. These precatalysts appear as highly efficient, easily recovered and reused at least eight times without any drastic loss of their exceptional reactivity or leaching from the ionic liquid medium.

  • Sustainable carbon–carbon bond formation catalyzed by new Oxamate-containing palladium(II) complexes in ionic liquids
    Journal of Organometallic Chemistry, 2013
    Co-Authors: Francisco R. Fortea-pérez, Miguel Julve, Donatella Armentano, Giovanni De Munno, Isabel Schlegel, Salah-eddine Stiriba
    Abstract:

    Abstract New and versatile bis(oxamato)palladate(II) complexes of formula ( n -Bu 4 N) 2 [Pd(2-Mepma) 2 ]·4H 2 O ( 1a ) and ( n -Bu 4 N) 2 [Pd(4-Mepma) 2 ]·2H 2 O·MeCN ( 1b ) ( n -Bu 4 N +  = tetra- n -buthylammonium, 2-Mepma =  N -2-methylphenylOxamate and 4-Mepma =  N -4-methylphenylOxamate) have been synthesized and characterized by spectroscopic methods and single crystal X-ray diffraction. Each palladium(II) ion in 1a and 1b is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated Oxamate ligands building a centrosymmetric square planar surrounding. Their catalytic role has been investigated for both Heck and Suzuki coupling reactions using a series of aryl iodide/bromide derivatives in tetra- n -butylammonium bromide ( n -Bu 4 NBr) as ionic liquid, i.e. molten salt. These precatalysts appear as highly efficient, easily recovered and reused at least eight times without any drastic loss of their exceptional reactivity or leaching from the ionic liquid medium.

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