High-nuclearity ruthenium carbonyl cluster complexes derived from 2-amino-6-methylpyridine: Synthesis of nonanuclear derivatives containing mu(4)- and mu(5)-oxo Ligands

Departamento de Química Organica e Inorganica, Instituto de Química Organometalica Enrique Moles, Universidad de Oviedo-CSIC, E-33071 Oviedo, Spain.
Inorganic Chemistry (Impact Factor: 4.79). 08/2006; 45(15):6020-7. DOI: 10.1021/ic060433o
Source: PubMed

ABSTRACT Nonanuclear cluster complexes [Ru9(mu3-H)2(mu-H)(mu5-O)(mu4-ampy)(mu3-Hampy)(CO)21] (4) (H2ampy = 2-amino-6-methylpyridine), [Ru9(mu5-O)2(mu4-ampy)(mu3-Hampy)2(mu-CO)(CO)20] (5), [Ru9(mu5-O)2(mu4-ampy)(mu3-Hampy)2(mu-CO)2(CO)19] (6), and [Ru9(mu4-O)(mu5-O)(mu4-ampy)(mu3-Hampy)(mu-Hampy)(mu-CO)(CO)19] (7), together with the known hexanuclear [Ru6(mu3-H)2(mu5-ampy)(mu-CO)2(CO)14] (2) and the novel pentanuclear [Ru5(mu4-ampy)(2)(mu-CO)(CO)12] (3) complexes, are products of the thermolysis of [Ru3(mu-H)(mu3-Hampy)(CO)9] (1) in decane at 150 degrees C. Two different and very unusual quadruply bridging coordination modes have been observed for the ampy ligand. Compounds 4-7 also feature one (4) or two (5-7) bridging oxo ligands. With the exception of one of the oxo ligands of 7, which is in a distorted tetrahedral environment, the remaining oxo ligands of 4-7 are surrounded by five metal atoms. In carbonyl metal clusters, quadruply bridging oxo ligands are very unusual, whereas quintuply bridging oxo ligands are unprecedented. By using 18O-labeled water, we have unambiguously established that these oxo ligands arise from water.

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    ABSTRACT: Three high-nuclearity osmium carbonyl cluster complexes, [Os-7(mu(5)-kappa(2)-ampy)(mu-CO)(2)(CO)(17)] (1), [Os-8(mu(3)-Eta)(mu-H)(mu(5)-kappa(2)-ampy)(mu-CO)(CO)(19)] (2), and [Os9O(mu(4)-kappa(2)-ampy)(2)(CO)(18)] (3) (H(2)ampy = 2-amino-6-methylpyridine), have been prepared by heating [Os-3(CO)(12)] with 0.5 equiv of H(2)ampy in decane at reflux temperature. The trinuclear complex [Os-3(mu-Eta)(mu(3)-kappa(2)-Hampy)(CO)(9)] is an intermediate in this reaction. The metallic skeletons of 1 and 2 can be described as mono- (1) or bi-face-capped (2), basal-edge-bridged, square pyramids, whereas that of compound 3 consists of a pentagonal bipyramid with two equatorial edges spanned by metal atoms. In the three clusters, the ampy ligands are attached to edge-bridging Ru atoms through their pyridine N atoms, while they also cap metallic squares (in 1 and 2) or triangles (in 3) through their imido N atom. An additional feature of compound 3 is that it contains a terminal oxo ligand, unprecedented in osmium carbonyl cluster chemistry.
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