Chromium complexes thiocarbonyls

The relative amounts of the products depend on irradiation time, and the formation of the bis (triphenyl phosphite) chromium complex may be almost completely avoided by following the reaction with thin layer chromatography. The diastereoisomers are air stable and reasonably soluble in most organic solvents. Their infrared spectra exhibit a metal carbonyl band at 1925 cm 1 (i>co ester at 1729 cm"1) and a metal thiocarbonyl band at 1925 cm"1 (CH2C12 solution). The NMR spectra. I 5ch3 at 1.87 ppm 5co3CH3 at 3.77 ppm II 6ch3 at 1.77... 

The preparations of several (arene)(thiocarbonyl)chromium(0) complexes bearing electron-donating and/or electron-withdrawing substituents on the ring are described here (A-E). This type of compound is useful in organometallic chemistry for problems related to stereochemistry around a chromium atom6 and in organic chemistry in the activation of arene substituents with respect to alkylation.7... 

The intermediate cyclooctene complex appears to be more reactive with respect to CS coordination and more sensitive to oxidation when the arene ring bears electron-withdrawing groups (e.g., C02CH3). Dicarbonyl(methyl rj6-benzoate)-thiocarbonyl)chromium is air stable in the solid state and reasonably stable in solution.9 The infrared spectrum exhibits metal carbonyl absorptions at 1980 and 1935 cm"1 and a metal thiocarbonyl stretch at 1215 cm"1 (Nujol) (these occur at 1978, 1932, and 1912 cm"1 in CH2C12 solution).10 Irradiation of the compound in the presence of phosphite or phosphine leads to slow substitution of CO by these ligands, whereas the CS ligand remains inert to substitution. The crystal structure has been published."... 

Among the types of complexes found here are formyl, acyl, alkyl, and aryl carbonyls, carbonyl cyanides," " carbonyl isocyanides and acetylides," and thiocarbonyl and seleno-carbonyl complexes." Of the greatest significance, however, are the chromium carbenes, for example, (CO)sCr=C(OR)R". This chemistry has been thoroughly reviewed " nevertheless, these compounds will be briefly discussed here. 

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