Khenkin Alexander M, Shimon Linda J W, Neumann Ronny
Department of Organic Chemistry and Division of Chemical Services, Weizmann Institute of Science, Israel, 76100.
Inorg Chem. 2003 May 19;42(10):3331-9. doi: 10.1021/ic026003p.
A new heptamolybdate polyoxometalate structure containing ruthenium(II) or osmium(II) metal centers, M(II)(DMSO)(3)Mo(7)O(24) (M = Ru, Os), was synthesized by reaction between (NH(4))(6)Mo(7)O(24) and cis-M(DMSO)(4)Cl(2). X-ray structure analysis revealed the complexes to contain a ruthenium/osmium center in a trigonal antiprismatic coordination mode bound to three DMSO moieties via the sulfur atom of DMSO and three oxygen atoms of the new heptamolybdate species. The heptamolybdate consists of seven condensed edge-sharing MoO(6) octahedra with C(2v) symmetry. Three Mo atoms are in classic type II octahedra with a cis dioxo configuration. Two Mo atoms are also type-II-like, but one of the short Mo-O bonds is associated with bridging oxygen atoms rather than terminal oxygen atoms. Two molybdenum atoms are unique in that they are in a trigonally distorted octahedral configuration with three short Mo-O bonds and two intermediate-long M-O bonds and one long Mo-O bond. The M(II)(DMSO)(3)Mo(7)O(24) polyoxometalates were effective and in some cases highly selective catalysts for the aerobic oxidation of alcohols to ketones/aldehydes. The integrity of the polyoxometalate was apparently retained at high turnover numbers and throughout the reaction, and a variation of an oxometal type mechanism was proposed to explain the results.
通过(NH₄)₆Mo₇O₂₄与顺式-M(DMSO)₄Cl₂反应合成了一种含有钌(II)或锇(II)金属中心的新型七钼酸多金属氧酸盐结构[M(II)(DMSO)₃Mo₇O₂₄]⁴⁻（M = Ru，Os）。X射线结构分析表明，该配合物含有一个处于三角反棱柱配位模式的钌/锇中心，它通过DMSO的硫原子和新型七钼酸盐物种的三个氧原子与三个DMSO部分相连。七钼酸盐由七个具有C₂ᵥ对称性的缩合边共享MoO₆八面体组成。三个钼原子处于具有顺式双氧构型的经典II型八面体中。两个钼原子也类似II型，但其中一个短的Mo - O键与桥连氧原子而非端基氧原子相关。两个钼原子独特之处在于它们处于三角扭曲的八面体构型，有三个短的Mo - O键、两个中等长度的M - O键和一个长的Mo - O键。[M(II)(DMSO)₃Mo₇O₂₄]⁴⁻多金属氧酸盐对于醇类有氧氧化为酮/醛是有效的催化剂，在某些情况下具有高选择性。多金属氧酸盐的完整性在高周转数和整个反应过程中显然得以保留，并提出了一种氧金属类型机制的变体来解释这些结果。
