American Chemical Society
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High-Nuclearity Ruthenium Carbonyl Cluster Complexes Derived from 2-Amino-6-methylpyridine:  Synthesis of Nonanuclear Derivatives Containing μ4- and μ5-Oxo Ligands

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posted on 2006-07-24, 00:00 authored by Javier A. Cabeza, Ignacio del Río, Pablo García-Álvarez, Daniel Miguel
Nonanuclear cluster complexes [Ru93-H)2(μ-H)(μ5-O)(μ4-ampy)(μ3-Hampy)(CO)21] (4) (H2ampy = 2-amino-6-methylpyridine), [Ru95-O)24-ampy)(μ3-Hampy)2(μ-CO)(CO)20] (5), [Ru95-O)24-ampy)(μ3-Hampy)2(μ-CO)2(CO)19] (6), and [Ru94-O)(μ5-O)(μ4-ampy)(μ3-Hampy)(μ-Hampy)(μ-CO)(CO)19] (7), together with the known hexanuclear [Ru63-H)25-ampy)(μ-CO)2(CO)14] (2) and the novel pentanuclear [Ru54-ampy)2(μ-CO)(CO)12] (3) complexes, are products of the thermolysis of [Ru3(μ-H)(μ3-Hampy)(CO)9] (1) in decane at 150 °C. Two different and very unusual quadruply bridging coordination modes have been observed for the ampy ligand. Compounds 47 also feature one (4) or two (57) 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 47 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.