Quadruple Bond

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Albert F Cotton - One of the best experts on this subject based on the ideXlab platform.

  • isomerization by ligand shuffling along a cr24 unit further reactions leading to cleavage of a Quadruple Bond
    Dalton Transactions, 2003
    Co-Authors: Albert F Cotton, Carlos A Murillo, Rodolphe Clerac, Stephen P Jeffery, Xiaoping Wang
    Abstract:

    The paddlewheel complex Cr2(DpyF)4 (1), where DpyF = N,N′-di(2-pyridyl)formamidinate, has a short Cr–Cr distance of 1.938(2) A for the CrCr Quadruple Bond. In solution, there is a series of interconverting isomers, as determined by variable temperature 1H NMR studies. Compound 1 can be readily oxidized by CuCl2 to produce [Cr2(DpyF)4][CuCl2]2 (2) and [Cr2(DpyF)4CuCl3][CuCl2] (3). In both cases, the metal–metal Quadruple Bond is cleaved in favor of six-coordinate Cr(III) ions. Magnetic measurements for the oxidized products show that the chromium ions in the dichromium units exhibit strong antiferromagnetic interactions.

  • synthesis and reactivity of a very strong reducing agent containing a Quadruple Bond structures of w2 hpp 4 and w2 hpp 4cl2 4ch2cl2
    Inorganic Chemistry Communications, 2003
    Co-Authors: Albert F Cotton, Carlos A Murillo, Penglin Huang, Xiaoping Wang
    Abstract:

    Abstract The preparation and structural characterization of the very strong reducing agent W2(hpp)4, hpp = the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine, 1, has been accomplished. It has a short distance of 2.1617(4) A for the quadruply-Bonded W24+ unit. Compound 1 is very reactive and gives the triple Bonded W 2 ( hpp ) 4 Cl 2 ·4 CH 2 Cl 2 , 2 ·4 CH 2 Cl 2 , upon crystallization after mere contact with the haloalkane CH2Cl2. The change in electronic configuration from the σ2π4δ2 in 1 to the σ2π4 system in 2 increases the W–W distance by ca. 0.09 to 2.2497(8) A. W2(hpp)4 also reduces C60 and 7,7′, 8,8′-tetracyanoquinodimethide, TCNQ. The latter is reduced to the TCNQ2− anion while the W24+ unit is oxidized to the W26+ state.

  • remarkable effects of axial π coordination on the cr cr Quadruple Bond in dichromium paddlewheel complexes
    Journal of the American Chemical Society, 1999
    Co-Authors: Albert F Cotton, Carlos A Murillo, Lee M Daniels, And Isabel Pascual, Hongcai Zhou
    Abstract:

    It is well-known that donation of electron density into the σ* orbital of a Cr−Cr Quadruple Bond causes major lengthening of the Cr−Cr distance, and there is some prior evidence that a similar lengthening is caused by dative interaction with the π* orbitals. Some molecules have now been made that allow a definitive assessment of this axial π* effect. A molecule has been designed to ensure that there is axial donation into the π* orbitals but not onto the σ* orbital; ligands have been used in which the donor atoms are tethered to the bridging ligands in such a way that they can reach only the π* orbitals but not the σ* orbital. The ligands used for this purpose are the anions of 2,6-di(phenylimino)piperidine (DPhIP) and 2,2‘-dipyridylamine (dpa). In the compound Cr2(DPhIP)4 four imino nitrogen lone pairs are suitably positioned to donate to the π* orbitals and the Cr−Cr Bond length is 2.265(1) A. For direct comparison, the compound Cr2(PhIP)4 (PhIP is the anion of 2-(phenylimino)piperidine) was made and fo...

  • an unprecedented quadruply Bonded compound with a bridging chlorine atom cr2 o clc6h4n 2ch 3 μ cl
    Inorganic Chemistry Communications, 1999
    Co-Authors: Albert F Cotton, Carlos A Murillo, Isabel Pascual
    Abstract:

    Abstract Reaction of CrCl2 and Li[(o-ClC6H4N)2CH] in THF gives Cr2[(o-ClC6H4N)2CH]3(μ-Cl). This compound has three bridging formamidinates and a bridging chlorine atom. The resulting A-frame is the first having a quadruply Bonded M24+ unit. The Cr–Cr distance of 1.940(1) A is in the normal range for a short Quadruple Bond.

  • a very short re26 Quadruple Bond first dft calculations on a paddlewheel complex with an element of the third transition series
    Journal of The Chemical Society-dalton Transactions, 1999
    Co-Authors: Albert F Cotton, Carlos A Murillo, Daren J Timmons
    Abstract:

    The first complexes containing third row transition elements with bridging hpp (the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) are presented. Re2(hpp)4Cl2, 1, is a typical paddlewheel complex with two axial chloride ions. The Re–Re distance in 1 of 2.191(1) A is one of the shortest known for a quadruply-Bonded Re26+ complex and the Re–Cl distance of 2.749(5) A is the longest one reported for this type of complex. The second compound, Re2(hpp)3Cl3, 2, has three bridging hpp ligands, two equatorial chloride ions and one axial chloride ion. The Re–Re distance is 2.189(2) A. The electronic structure of 1 has been determined by DFT calculations, the first time this has been done on a paddlewheel complex containing a third row transition element.

Ernesto Carmona - One of the best experts on this subject based on the ideXlab platform.

  • reactivity of a trans h mo Quadruple Bond length as m dash mo h unit towards alkenes and alkynes bimetallic migratory insertion h elimination and other reactions
    Chemical Communications, 2018
    Co-Authors: Marina Perezjimenez, Jesus Campos, Joaquin Lopezserrano, Ernesto Carmona
    Abstract:

    Complex [Mo2(H)2{μ-HC(NDipp)2}2(THF)2], (1·THF), reacts with C2H4 and PhCH[double Bond, length as m-dash]CH2 to afford hydrido-hydrocarbyl and bis(hydrocarbyl) derivatives of the Mo[Quadruple Bond, length as m-dash]Mo Bond. Reversible migratory insertion and β-hydrogen elimination, as well as reductive elimination and other reactions, have been uncovered. PhC[triple Bond, length as m-dash]CH behaves instead as a Bronsted-Lowry acid towards the strongly basic Mo-H Bonds of 1·THF.

  • an unsaturated four coordinate dimethyl dimolybdenum complex with a molybdenum molybdenum Quadruple Bond
    Chemistry: A European Journal, 2017
    Co-Authors: Natalia Curado, Mario Carrasco, Jesus Campos, Celia Maya, Amor Rodriguez, Eliseo Ruiz, Santiago Alvarez, Ernesto Carmona
    Abstract:

    We describe the synthesis and the molecular and electronic structures of the complex [Mo2 Me2 {μ-HC(NDipp)2 }2 ] (2; Dipp=2,6-iPr2 C6 H3 ), which contains a dimetallic core with an Mo-Mo Quadruple Bond and features uncommon four-coordinate geometry and has a fourteen-electron count for each molybdenum atom. The coordination polyhedron approaches a square pyramid, with one of the molybdenum atoms nearly co-planar with the basal square plane, in which the trans coordination position with respect to the Mo-Me Bond is vacant. The other three sites are occupied by two trans nitrogen atoms of different amidinate ligands and the methyl group. The second Mo atom occupies the apex of the pyramid and forms an Mo-Mo Bond of length 2.080(1) A, consistent with a Quadruple Bond. Compound 2 reacts with tetrahydrofuran (THF) and trimethylphosphine to yield the mono-adducts [Mo2 Me(μ-Me){μ-HC(NDipp)2 }2 (L)] (3⋅THF and 3⋅PMe3 , respectively) with one terminal and one bridging methyl group. In contrast, 4-dimethylaminopyridine (dmap) forms the bis-adduct [Mo2 Me2 {μ-HC(NDipp)2 }2 (dmap)2 ] (4), with terminally coordinated methyl groups. Hydrogenolysis of complex 2 leads to the bis(hydride) [Mo2 H2 {μ-HC(NDipp)2 }2 (thf)2 ] (5⋅THF) with elimination of CH4 . Computational, kinetic, and mechanistic studies, which included the use of D2 and of complex 2 labelled with 13 C (99 %) at the Mo-CH3 sites, supported the intermediacy of a methyl-hydride reactive species. A computational DFT analysis of the terminal and bridging coordination of the methyl groups to the Mo≣Mo core is also reported.

Lee M Daniels - One of the best experts on this subject based on the ideXlab platform.

Hongcai Zhou - One of the best experts on this subject based on the ideXlab platform.

  • oxidative scission of a mo mo Quadruple Bond
    Inorganic Chemistry, 2000
    Co-Authors: F A Cotton, Carlos A Murillo, Hongcai Zhou
    Abstract:

    Two compounds containing the cations Mo2(DPhIP)4n+, n = 1 or 2 and DPhIP = the anion of 2,6-diphenyliminopiperidine, have been obtained by oxidation of the quadruply-Bonded Mo2(DPhIP)4 species. The first oxidation process conserves the structure but results in a slight increase of the Mo−Mo distance from 2.114(1) to 2.136(2) A in [Mo2(DPhIP)4](PF6)·2CH2Cl2 (1·2CH2Cl2). However, the second oxidation process breaks the dimolybdenum Bond, giving a bioctahedral complex, [Mo2(DPhIP)4](BF4)2·5CH3CN·Et2O (2·5CH3CN·Et2O), with Mo···Mo separation of 2.9954(7) A. Crystallographic data for 1·2CH2Cl2 are space group C2/c, a = 17.1891(9) A, b = 17.807(1) A, c = 24.210(2) A, β = 106.403(4)°, Z = 4; for 2·5CH3CN·Et2O, space group P21/n, a = 16.523(5) A, b = 27.418(5) A, c = 18.163(3) A, β = 93.48(2)°, Z = 4.

  • remarkable effects of axial π coordination on the cr cr Quadruple Bond in dichromium paddlewheel complexes
    Journal of the American Chemical Society, 1999
    Co-Authors: Albert F Cotton, Carlos A Murillo, Lee M Daniels, And Isabel Pascual, Hongcai Zhou
    Abstract:

    It is well-known that donation of electron density into the σ* orbital of a Cr−Cr Quadruple Bond causes major lengthening of the Cr−Cr distance, and there is some prior evidence that a similar lengthening is caused by dative interaction with the π* orbitals. Some molecules have now been made that allow a definitive assessment of this axial π* effect. A molecule has been designed to ensure that there is axial donation into the π* orbitals but not onto the σ* orbital; ligands have been used in which the donor atoms are tethered to the bridging ligands in such a way that they can reach only the π* orbitals but not the σ* orbital. The ligands used for this purpose are the anions of 2,6-di(phenylimino)piperidine (DPhIP) and 2,2‘-dipyridylamine (dpa). In the compound Cr2(DPhIP)4 four imino nitrogen lone pairs are suitably positioned to donate to the π* orbitals and the Cr−Cr Bond length is 2.265(1) A. For direct comparison, the compound Cr2(PhIP)4 (PhIP is the anion of 2-(phenylimino)piperidine) was made and fo...

Swarup Chattopadhyay - One of the best experts on this subject based on the ideXlab platform.

  • sulphido bridged dinuclear Quadruple Bond cleavage product from the reaction between re2 µ o2cch3 4cl2 and dithiocarbamate an experimental and theoretical study
    Polyhedron, 2021
    Co-Authors: Suman Mallick, Purnananda Garu, Jagannath Chowdhury, Rajat Saha, Swarup Chattopadhyay
    Abstract:

    Abstract Sodium salts of dimethyldithiocarbamate, diethyldithiocarbamate and pyrrolidinedithiocarbamate react with the quadruply Bonded dirhenium(III,III) complex [Re2(μ-O2CCH3)4Cl2] (1) in ethanol to afford the sulphido bridged dinuclear Quadruple-Bond cleavage products of the type [Re2(μ-S)(LR)4(OH2)2] (2(LR)) where LR represents the dithiocarbamato ligands [LR = S2CNMe2, 2(LMe); S2CNEt2, 2(LEt) and S2CN(CH2)4, 2(LPyr)]. Complexes 2(LR) are the first example of sulphido bridged dinuclear Re(III) complexes containing the chelating dithiocarbamato ligands. The spectral (IR, UV–vis, NMR) and electrochemical properties of this series of complexes are reported. The identity of 2(LEt) has been established by single-crystal X-ray structure determination. The electronic structure and the absorption spectra of the complexes are scrutinized by the density functional theory (DFT) and time-dependent DFT (TD-DFT) analyses.

  • reactions of the dirhenium iii complex re2 μ o2cch3 4cl2 with triphenylguanidine dirhenium paddlewheel complex versus the mononuclear Quadruple Bond cleavage product
    Polyhedron, 2014
    Co-Authors: Suman Mallick, Rajat Saha, Mrinal Kanti Ghosh, Swarup Chattopadhyay
    Abstract:

    Abstract The reaction of the quadruply Bonded dirhenium(III) complex Re2(μ-O2CCH3)4Cl2 (1) with 1,2,3-triphenylguanidine (abbreviated as HTPG) affords the ionic compounds [H2TPG][ReO4] (2) and [Re2(μ-TPG)3(μ-O2CCH3)Cl]Cl (3), depending upon the water content of the solvent used in the reaction. Cleavage of the Re–Re multiply Bond with concomitant oxidation of the rhenium unit occurred in the formation of 2. Conductivity measurements of compounds 2 and 3 in acetone solution confirmed their electrolytic nature. The electronic spectra of 2 are solvent dependent and luminescence studies showed that the solvent with a stronger H-Bond formation capability perturbs both the intensity and the energy of the emission spectra. Single crystal X-ray structural details are reported for 2 and 3. In both cases supramolecular networks are formed in the solid state via H-Bonding. One dimensional zigzag supramolecular chains are formed by C–H⋯π intermolecular interactions, and anion⋯π interactions are also apparent in the solid state structure of 2.