Tellurocarbonyl complexes

The first tellurocarbonyl complex, which is also the only osmium complex of an organotellurium ligand, is the recently reported112 OsCl2(PPh3)2(CO)CTe species. 

G. R. Clark, K. Marsden, W. R. Roper, and L. J. Wright, Carbonyl, Thiocarbonyl, Selenocarbonyl, and Tellurocarbonyl Complexes Derived from a Dihalocarbene Complex of Osmium, J. Am. Chem. Soc. 102, 1206-1207 (1980). 

In most cases, synthesis of CS (thiocarbonyl), CSe (selenocarbonyl), and CTe (tellurocarbonyl) complexes is somewhat more difficult than that for analogous CO complexes, since CS, CSe, and CTe do not exist as stable, free molecules and do not, therefore, provide a ready ligand source.16 Consequently, the comparatively small number of such complexes should not be viewed as an indication of their stability the chemistry of complexes of these three ligands may eventually rival that of CO complexes in breadth and utility. CS complexes are also of interest as possible intermediates in certain sulfur-transfer reactions in the removal of sulfur from natural fuels. In recent years, the chemistry of complexes containing... 

Carbon monosulfide is not a stable molecule, but carbon monosulfide complexes (more commonly called thiocarbonyl complexes) are known for most of the transition metals. Because of the mstability of free CS, most CS complexes have been prepared by generation of CS from CS, Cl CS, or EtOC(S)Cl in the coordination sphere of the metal, as shown in Equations 2.5, 2.6, and 2.7. Thiocarbonyl ligands vibrate between 1160 and 1410 cm" free CS (in a matrix) vibrates at 1274 cm". A detailed analysis of force constants of mixed carbonyl and thiocarbonyl complexes indicates that the CS ligand can be a weaker or stronger TT-acceptor tiian CO. Seleno- and tellurocarbonyl complexes are also known. ... 

The most straightforward route to heteroaldehyde and heteroketone complexes is the substitution of a heterocarbonyl compound for another coordinated ligand. This method is naturally restricted to heteroaldehydes and heteroketones stable in the uncoordinated form, i.e., is usually restricted to thioketones and a few stable seleno- and tellurocarbonyl compounds.141718,27118 In most cases, metal carbonyls or solvent complexes of metal carbonyls were used as the complex precursors. The photochemically or thermally induced loss of the ligand to be replaced is followed by coordination of the heterocarbonyl compound [Eq. (3)]. 

Complexes with tellurocarbonyl ligands such as telluroureas can be formulated as tellurolate complexes. 

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