Sellmann Dieter, Gottschalk-Gaudig Torsten, Heinemann Frank W.
Institut für Anorganische Chemie der Universität Erlangen-Nürnberg, Egerlandstrasse 1, D-91058 Erlangen, Germany.
Inorg Chem. 1998 Aug 10;37(16):3982-3988. doi: 10.1021/ic971068r.
Hydride and eta(2)-H(2) ruthenium complexes with sulfur-rich coordination spheres were synthesized. Substitution of either DMSO or PPh(3) in [Ru(DMSO)(PR(3))('S(4)')] and [Ru(PPh(3))(2)('S(4)')] by hydride anions from LiAlH(4) or NaBEt(3)H yielded Ru(H)(PR(3))('S(4)') complexes (R = (i)Pr, Ph, Cy; 'S(4)'(2)(-) = 1,2-bis((2-mercaptophenyl)thio)ethane(2-)). They were isolated as [Li(THF)(Et(2)O)][Ru(H)(PR(3))('S(4)')] (R = (i)Pr (1a), Cy (1b), Na[Ru(H)(PCy(3))('S(4)')].2BEt(3).0.5DMSO (2a), and the solvent-free Na[Ru(H)(PPh(3))('S(4)')].2BEt(3) (2b). X-ray structure determinations of 1a.0.5Et(2)O and 1b.Et(2)O showed that in both complexes pseudooctahedral Ru(H)(PR(3))('S(4)') anions are bridged to pseudotetrahedral [Li(THF)(Et(2)O)] cations via the hydride ligand and one thiolate donor of the 'S(4)'(2)(-) ligand (crystal data: 1a, monoclinic, P2(1)/n, a = 1401.6(2) pm, b = 1045.2(3) pm, c = 2590.6(4) pm, beta = 95.04(1) degrees, V = 3.780(1) nm(3), Z = 4; 1b, triclinic, P&onemacr;, a = 1264.2(1) pm, b = 1322.9(3) pm, c = 1569.5(2) pm, alpha = 88.96(1) degrees, beta = 83.48(1) degrees, gamma = 62.16(1) degrees, V = 2.3042(6) nm(3), Z = 2). Short intramolecular C-H.H-Ru contacts ( approximately 230 pm) between the hydride ligands, phosphine substituents, and lithium-coordinated Et(2)O molecules indicate "unconventional" hydrogen bonds. They potentially help to decrease the hydridic character of the hydride ligand to such an extent that no structural hydride trans influence can be observed in the solid state. In solution at room temperature, all hydride complexes 1a-2b rapidly release H(2) or HD, when treated with CH(3)OH or CD(3)OD. Low-temperature (1)H and (2)H NMR spectroscopy between -20 and -80 degrees C showed that initially eta(2)-H(2) or eta(2)-HD complexes form. Their formation explains the observed scrambling between protons and hydride ligands, which requires a heterolytic cleavage of dihydrogen. A 1:1:1 triplet at delta = -6.5 ppm ((1)J(HD) = 32 Hz, (2)J(PH) = 5 Hz) and a relaxation time of T(1)(min) = 4 ms (-60 degrees C, 270 MHz) firmly established the formation of the eta(2)-dihydrogen complexes. The reversibility of H(2) release and uptake by [Ru(PCy(3))('S(4)')] fragments and the heterolytic cleavage of H(2) in [Ru(eta(2)-H(2))(PCy(3))('S(4)')] was further ascertained by the reaction of [Ru(DMSO)(PCy(3))('S(4)')] with H(2) in the presence of NaOMe, yielding the Ru(H)(PCy(3))('S(4)') anion. The relevance of the complexes and their reactions for the heterolytic H(2) activation at the transition metal sulfur sites of hydrogenases is discussed.
合成了具有富硫配位球的氢化物和η(2)-H₂钌配合物。用LiAlH₄或NaBEt₃H中的氢化物阴离子取代[Ru(DMSO)(PR₃)(‘S₄’)]和[Ru(PPh₃)₂(‘S₄’)]中的DMSO或PPh₃，得到[Ru(H)(PR₃)(‘S₄’)]⁻配合物（R = (i)Pr、Ph、Cy；‘S₄’²⁻ = 1,2-双((2-巯基苯基)硫代)乙烷(2⁻)）。它们被分离为[Li(THF)(Et₂O)][Ru(H)(PR₃)(‘S₄’)]（R = (i)Pr (1a)、Cy (1b)）、Na[Ru(H)(PCy₃)(‘S₄’)].2BEt₃.0.5DMSO (2a)以及无溶剂的Na[Ru(H)(PPh₃)(‘S₄’)].2BEt₃ (2b)。1a.0.5Et₂O和1b.Et₂O的X射线结构测定表明，在这两种配合物中，伪八面体[Ru(H)(PR₃)(‘S₄’)]⁻阴离子通过氢化物配体和‘S₄’²⁻配体的一个硫醇盐供体与伪四面体[Li(THF)(Et₂O)]阳离子桥连（晶体数据：1a，单斜晶系，P2(1)/n，a = 1401.6(2) pm，b = 1045.2(3) pm，c = 2590.6(4) pm，β = 95.04(1)°，V = 3.780(1) nm³，Z = 4；1b，三斜晶系，P&onemacr;，a = 1264.2(1) pm，b = 1322.9(3) pm，c = 1569.5(2) pm，α = 88.96(1)°，β = 83.48(1)°，γ = 62.16(1)°，V = 2.3042(6) nm³，Z = 2）。氢化物配体、膦取代基与锂配位的Et₂O分子之间短的分子内C-H···H-Ru接触（约230 pm）表明存在“非常规”氢键。它们可能有助于在一定程度上降低氢化物配体的氢化物性质，以至于在固态中未观察到结构上的氢化物反位影响。在室温下的溶液中，当用CH₃OH或CD₃OD处理时，所有氢化物配合物1a - 2b都会迅速释放H₂或HD。在-20至-80℃之间进行的低温¹H和²H NMR光谱表明，最初形成η(2)-H₂或η(2)-HD配合物。它们的形成解释了观察到的质子和氢化物配体之间的交换，这需要二氢的异裂。在δ = -6.5 ppm处的1:1:1三重峰（¹J(HD) = 32 Hz，²J(PH) = 5 Hz）以及T₁(min) = 4 ms的弛豫时间（-60℃，270 MHz）有力地证实了η(2)-二氢配合物的形成。通过[Ru(DMSO)(PCy₃)(‘S₄’)]与H₂在NaOMe存在下的反应生成[Ru(H)(PCy₃)(‘S₄’)]⁻阴离子，进一步确定了[Ru(PCy₃)(‘S₄’)]片段释放和吸收H₂的可逆性以及[Ru(η(2)-H₂)(PCy₃)(‘S₄’)]中H₂的异裂。讨论了这些配合物及其反应对于氢化酶过渡金属硫位点上H₂异裂活化的相关性。
