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Hideo Nagashima – One of the best experts on this subject based on the ideXlab platform.

  • Preparation and Structural Elucidation of Unusually Thermally Stable Novel Alkylruthenium Complexes Bearing Amidin’ate Ligands, (n6-C6H6)Ru(n-amidinate)R (R  =  Me ,  Et ,  Bn)
    , 2016
    Co-Authors: Taizo Hayashida, Hideo Nagashima

    Abstract:

    The first organoruthenium Amidinates bearing a Ru-C 6 bond were prepared ,  and their stmctures were elucidated by spectroscopy and crystallography .  A halogenoruthenium amidinate precursor ,  [(n 6-C6H6)Ru(n-tBuNCPhNtBu)Cl] ,  was treated with Grignard reagents to form thermally and air stable alky1 ruthenium complexes ,  [(n6-C6H6)Ru(n一‘BuNCPhNtBu)R ]  (R  =  Me (3a) ,  Et (3b) ,  Bn (3c)) .  C,一symmetric ‘piano stool ’  structures of these complexes were suggested from NMR spectroscopic data .  These were supported by crystallographic studies of 3b and 3c

  • trifluoromethanesulfonate triflate as a moderately coordinating anion studies from chemistry of the cationic coordinatively unsaturated mono and diruthenium Amidinates
    Journal of Organometallic Chemistry, 2007
    Co-Authors: Taizo Hayashida, Karl Kirchner, Hideo Kondo, Junichi Terasawa, Yusuke Sunada, Hideo Nagashima

    Abstract:

    Abstract Triflate complexes of mono- and diruthenium Amidinates, (η6-C6R6)Ru(κ1-OTf){η2-R′N C(R′′)NR′} (1: R = Me; 2: R = H) and (η5-C5Me5)Ru(μ-η2-iPrN C(Me)NiPr)Ru(κ1-OTf)(η5-C5R5) (3: R = Me; 4: R = H), are synthesized, and coordination behavior of the triflate anion to the coordinatively unsaturated ruthenium species is investigated by crystallography and variable temperature (VT) NMR spectroscopy (19F, 1H). The monoruthenium amidinate complexes have three-legged piano-stool structures in single crystals, which include a κ1-OTf ligand with the Ru–O bond of 2.15–2.20 A. In contrast, reversible dissociation of OTf is observed in variable temperature 1H NMR spectroscopy in liquid states; the activation energy for the dissociation and recombination of the OTf ligand is varied with the substituents on the arene and amidinate ligand in the corresponding ruthenium cation and the solvent used. A typical example of moderately coordinating ability of the OTf ligand is seen in 19F NMR spectra of (η6-C6Me6)Ru(κ1-OTf){η2-iPrN C(Me)NiPr} (1a) and (η6-C6H6)Ru(κ1-OTf){η2-iPrN C(Me)NiPr} (2a) in CD2Cl2 at the temperature range from −90 to 20 °C, in which the OTf anion is dissociated in 1a, whereas 2a has a relatively robust Ru–OTf bond. Combination of crystallography and VT NMR contributes to understanding the difference in coordination behavior of the OTf ligand between two diruthenium Amidinates, (η5-C5Me5)Ru(μ-η2-iPrN C(Me)NiPr)Ru(κ1-OTf)(η5-C5Me5) (3) and (η5-C5Me5)Ru(μ-η2-iPrN C(Me)NiPr)Ru(κ1-OTf)(η5-C5H5) (4); the results suggest that the electron-donating and sterically demanding η5-C5Me5 helps for dissociation of the triflate ligand. Moderate coordinating ability of the triflate anion sometimes provides characteristic reactions of mono- and diruthenium Amidinates which differ from the corresponding neutral halogeno-compounds or cationic coordinatively unsaturated homologues bearing fluorinated tetraarylborates; a typical example is given by inhibition of coordination of ethylene to the [(η6-C6H6)Ru{η2-tBuN C(Ph)NtBu}]+ species by the OTf ligand.

  • “Unsymmetrical” Diruthenium Amidinates in Which the μ2-Amidinate Bridge Is Perpendicular to the Ru−Ru Axis: Synthesis and Reactions of Derivatives of [(η5-C5Me5)Ru(μ-amidinate)Ru(η5-C5H5)]+
    Organometallics, 2005
    Co-Authors: Junichi Terasawa, Karl Kirchner, Hideo Kondo, Taisuke Matsumoto, Yukihiro Motoyama, Hideo Nagashima

    Abstract:

    New diruthenium complexes, of which two organoruthenium species, (η5-C5Me5)Ru and (η5-C5H5)Ru, are linked by a bridging amidinate ligand, were synthesized and characterized. Treatment of (η5-C5Me5)Ru(η-amidinate) [amidinate:  iPrNC(Me)NiPr] with [(η5-C5H5)Ru(η-NCMe)3]+PF6- resulted in formation of a cationic diruthenium amidinate, [(η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5H5)(η-NCMe)]+PF6- (4), which was converted to (η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5H5)X [X = Cl (5a), Br (5b)] by treatment with the halide anion. The molecular structures and spectroscopic data of 4 and 5a including their solution dynamics are compared with their bis-pentamethylcyclopentadienyl homologues, [(η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5Me5)(η-NCMe)]+PF6- and (η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5H5)Cl. Treatment of 5a with TlBF4 produced a diruthenium complex, [(η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5H5)]+BF4- (6), bearing 34 valence electrons, which was isolated and characterized by spectroscopy. The coordinatively unsaturated nature of 6 was evidenc…

Frank T Edelmann – One of the best experts on this subject based on the ideXlab platform.

  • Crystal and mol-ecular structures of two silver(I) Amidinates, including an unexpected co-crystal with a lithium amidinate.
    Acta Crystallographica Section E Crystallographic Communications, 2016
    Co-Authors: Sida Wang, Nicole Harmgarth, Phil Liebing, Frank T Edelmann

    Abstract:

    The silver(I) Amidinates bis­[μ-N1,N2-bis­(propan-2-yl)benzamidinato-κ2N1:N2]disilver(I), [Ag2(C13H19N2)2] or [Ag{PhC(NiPr)2}]2 (1), and bis­(μ-N1,N2-di­cyclohexyl-3-cyclo­propyl­propynamidinato-κ2N1:N2)disilver(I), [Ag2(C18H27N2)2] or [Ag{cyclo-C3H5–C≡C–C(NCy)2}]2 (2a), exist as centrosymmetric dimers with a planar Ag2N4C2 ring and a common linear coordination of the metal atoms in the crystalline state. Moiety 2a forms a co-crystal with the related lithium amidinate, namely bis­(μ-N1,N2-di­cyclo­hexyl-3-cyclo­propyl­propynamidinato-κ2N1:N2)disilver(I) bis­(μ-N1,N2-di­cyclo­hexyl-3-cyclo­propyl­propynamidinato-κ3N1,N2:N1)bis­(tetra­hydro­furan-κO)lithium(I) toluene monosolvate, [Ag2(C18H27N2)2][Li2(C18H27N2)2(C4H8O)2]·C7H8 or [Ag{cyclo-C3H5–C≡C–C(NCy)2}]2[Li{cyclo-C3H5–C≡C–C(NCy)2}(THF)]2·C7H8, composed as 2a × 2b × toluene. The lithium moiety 2b features a typical ladder-type dimeric structure with a distorted tetra­hedral coordination of the metal atoms. In the silver(I) derivatives 1 and 2a, the amidinate ligand adopts a μ-κN:κN′ coordination, while it is a μ-κN:κN:κN′-coordination in the case of lithium derivative 2b.

  • Crystal and molecular structures of two silver(I) Amidinates, including an unexpected co-crystal with a lithium amidinate
    International Union of Crystallography, 2016
    Co-Authors: Sida Wang, Nicole Harmgarth, Phil Liebing, Frank T Edelmann

    Abstract:

    The silver(I) Amidinates bis[μ-N1,N2-bis(propan-2-yl)benzamidinato-κ2N1:N2]disilver(I), [Ag2(C13H19N2)2] or [Ag{PhC(NiPr)2}]2 (1), and bis(μ-N1,N2-dicyclohexyl-3-cyclopropylpropynamidinato-κ2N1:N2)disilver(I), [Ag2(C18H27N2)2] or [Ag{cyclo-C3H5–C[triple-bond]C–C(NCy)2}]2 (2a), exist as centrosymmetric dimers with a planar Ag2N4C2 ring and a common linear coordination of the metal atoms in the crystalline state. Moiety 2a forms a co-crystal with the related lithium amidinate, namely bis(μ-N1,N2-dicyclohexyl-3-cyclopropylpropynamidinato-κ2N1:N2)disilver(I) bis(μ-N1,N2-dicyclohexyl-3-cyclopropylpropynamidinato-κ3N1,N2:N1)bis(tetrahydrofuran-κO)lithium(I) toluene monosolvate, [Ag2(C18H27N2)2][Li2(C18H27N2)2(C4H8O)2]·C7H8 or [Ag{cyclo-C3H5–C[triple-bond]C–C(NCy)2}]2[Li{cyclo-C3H5–C[triple-bond]C–C(NCy)2}(THF)]2·C7H8, composed as 2a × 2b × toluene. The lithium moiety 2b features a typical ladder-type dimeric structure with a distorted tetrahedral coordination of the metal atoms. In the silver(I) derivatives 1 and 2a, the amidinate ligand adopts a μ-κN:κN′ coordination, while it is a μ-κN:κN:κN′-coordination in the case of lithium derivative 2b

  • chapter two recent progress in the chemistry of metal Amidinates and guanidinates syntheses catalysis and materials
    Advances in Organometallic Chemistry, 2013
    Co-Authors: Frank T Edelmann

    Abstract:

    This review provides a comprehensive overview of the most recent progress in chemistry and applications of metal complexes containing heteroallylic ligands such as Amidinates and guanidinates. Clearly, the coordination chemistry of Amidinates and guanidinates has reached a state of maturity and continues to be a highly popular area of research. These heteroallylic ligand systems allow a wealth of variations and modifications, making a larger ligand library available than in cyclopentadienyl chemistry. Exciting results have been obtained in recent years for almost any metallic elements in the Periodic Table. Truly remarkable developments include, for example, the chemistry of cyclic amidinate-based silylenes and the stabilization of metal–metal quadruply and quintuple bonds by amidinate and guanidinate ligands. The range of applications for metal Amidinates and guanidinates in homogeneous catalysis has considerably broadened in recent years. In materials science, alkyl-substituted metal Amidinates and guanidinates are now well established as volatile precursors for a variety of ALD and MOCVD processes. Without doubt the chemistry of metal Amidinates and guanidinates and related complexes will continue to produce exciting results and applications in the years to come.

Karl Kirchner – One of the best experts on this subject based on the ideXlab platform.

  • trifluoromethanesulfonate triflate as a moderately coordinating anion studies from chemistry of the cationic coordinatively unsaturated mono and diruthenium Amidinates
    Journal of Organometallic Chemistry, 2007
    Co-Authors: Taizo Hayashida, Karl Kirchner, Hideo Kondo, Junichi Terasawa, Yusuke Sunada, Hideo Nagashima

    Abstract:

    Abstract Triflate complexes of mono- and diruthenium Amidinates, (η6-C6R6)Ru(κ1-OTf){η2-R′N C(R′′)NR′} (1: R = Me; 2: R = H) and (η5-C5Me5)Ru(μ-η2-iPrN C(Me)NiPr)Ru(κ1-OTf)(η5-C5R5) (3: R = Me; 4: R = H), are synthesized, and coordination behavior of the triflate anion to the coordinatively unsaturated ruthenium species is investigated by crystallography and variable temperature (VT) NMR spectroscopy (19F, 1H). The monoruthenium amidinate complexes have three-legged piano-stool structures in single crystals, which include a κ1-OTf ligand with the Ru–O bond of 2.15–2.20 A. In contrast, reversible dissociation of OTf is observed in variable temperature 1H NMR spectroscopy in liquid states; the activation energy for the dissociation and recombination of the OTf ligand is varied with the substituents on the arene and amidinate ligand in the corresponding ruthenium cation and the solvent used. A typical example of moderately coordinating ability of the OTf ligand is seen in 19F NMR spectra of (η6-C6Me6)Ru(κ1-OTf){η2-iPrN C(Me)NiPr} (1a) and (η6-C6H6)Ru(κ1-OTf){η2-iPrN C(Me)NiPr} (2a) in CD2Cl2 at the temperature range from −90 to 20 °C, in which the OTf anion is dissociated in 1a, whereas 2a has a relatively robust Ru–OTf bond. Combination of crystallography and VT NMR contributes to understanding the difference in coordination behavior of the OTf ligand between two diruthenium Amidinates, (η5-C5Me5)Ru(μ-η2-iPrN C(Me)NiPr)Ru(κ1-OTf)(η5-C5Me5) (3) and (η5-C5Me5)Ru(μ-η2-iPrN C(Me)NiPr)Ru(κ1-OTf)(η5-C5H5) (4); the results suggest that the electron-donating and sterically demanding η5-C5Me5 helps for dissociation of the triflate ligand. Moderate coordinating ability of the triflate anion sometimes provides characteristic reactions of mono- and diruthenium Amidinates which differ from the corresponding neutral halogeno-compounds or cationic coordinatively unsaturated homologues bearing fluorinated tetraarylborates; a typical example is given by inhibition of coordination of ethylene to the [(η6-C6H6)Ru{η2-tBuN C(Ph)NtBu}]+ species by the OTf ligand.

  • “Unsymmetrical” Diruthenium Amidinates in Which the μ2-Amidinate Bridge Is Perpendicular to the Ru−Ru Axis: Synthesis and Reactions of Derivatives of [(η5-C5Me5)Ru(μ-amidinate)Ru(η5-C5H5)]+
    Organometallics, 2005
    Co-Authors: Junichi Terasawa, Karl Kirchner, Hideo Kondo, Taisuke Matsumoto, Yukihiro Motoyama, Hideo Nagashima

    Abstract:

    New diruthenium complexes, of which two organoruthenium species, (η5-C5Me5)Ru and (η5-C5H5)Ru, are linked by a bridging amidinate ligand, were synthesized and characterized. Treatment of (η5-C5Me5)Ru(η-amidinate) [amidinate:  iPrNC(Me)NiPr] with [(η5-C5H5)Ru(η-NCMe)3]+PF6- resulted in formation of a cationic diruthenium amidinate, [(η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5H5)(η-NCMe)]+PF6- (4), which was converted to (η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5H5)X [X = Cl (5a), Br (5b)] by treatment with the halide anion. The molecular structures and spectroscopic data of 4 and 5a including their solution dynamics are compared with their bis-pentamethylcyclopentadienyl homologues, [(η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5Me5)(η-NCMe)]+PF6- and (η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5H5)Cl. Treatment of 5a with TlBF4 produced a diruthenium complex, [(η5-C5Me5)Ru(μ2-amidinate)Ru(η5-C5H5)]+BF4- (6), bearing 34 valence electrons, which was isolated and characterized by spectroscopy. The coordinatively unsaturated nature of 6 was evidenc…

  • Chemistry of coordinatively unsaturated organoruthenium Amidinates as entry to homogeneous catalysis
    Coordination Chemistry Reviews, 2003
    Co-Authors: Hideo Nagashima, Hideo Kondo, Taizo Hayashida, Yoshitaka Yamaguchi, Mitsuru Gondo, Satoshi Masuda, Kazuma Miyazaki, Kouki Matsubara, Karl Kirchner

    Abstract:

    The chemistry of coordinatively unsaturated organoruthenium complexes is reviewed in this article. In particular, the subject is focused on neutral and cationic organoruthenium Amidinates, which formally have 16 valence electrons and show signs of coordinative unsaturation. The ruthenium Amidinates, ( 5 -C5Me5)Ru(-amidinate) (1), and their isoelectronic analogues, [( 6 -arene)Ru(-amidinate)] + (2), are synthesized and characterized; a possible stabilizing factor of the unsaturated metal center is weak coordination of -electrons in the Amidinates ligands. Reactions of various two-electron donor ligands with 1 or 2 reveal the strong -donor property of 1 and Lewis acid nature of 2. One or two-electron redox processes of 1 in the reactions with organic halides are studied by isolation of the corresponding Ru(III) and Ru(IV) products; the results lead to their catalysis for the Tsuji–Trost reaction and the intramolecular Kharasch reaction. The treatment of 2 with trimethylsilyldiazomethane results in the formation of cationic amidinato-carbene complexes, which involve unusual reversible metal-to-carbon silyl group migration. © 2003 Elsevier B.V. All rights reserved.