Thioketone-metal carbonyl reactions

Abstract

An account of the reaction of {(h -C,-H,)-M ?(CO) } and {(h -C5H.) M (CO) } (M=Mo,W) with aromatic and non-aromatic thiones to give mostly complexes of general molecular formula {(h -CJ (CO)4U (M=Mo, W; L=Thione) is given. {(h-C^CH^^o^O^) and {(h -CCH. CH_)/^lo/,(CO)/ } react with thiones in a similar manner. 5 4 3 2 2 4 Thiones used include thiofenchone, thiocamphor and 4,4'-dimethoxythiobenzophenone. Also complexes of general molecular formula ^ (CpJlo-(CO) L-} (n=either 3 or 4; L=thione; Cp= TT -C _H _ ) are isolated when {(h -C,-H£.)7Mo,>(CO)fi} is reacted with thiobenzophenone, 4,4'- dimethylthiobenzophenone, 4-methoxy thiobenzophenone, 4, 4 '-dif luorothiobenzophenone, thiocamphor and adamentanethione, and when {CpJto-(CO) } is reacted with 4, 4 '-dif luorothiobenzophenone«Complexes of the type {(h -C^R)^! (CO) L} (M=Mo,W; R=CH ,H; L=4-methoxythiobenzophenone, thiocamphor and adamantanethione) exist in at least two isomeric forms in non-polar and moderately polar solvents such as benzene, carbon tetrachloride and acetone. It is also noted that isomerisation depends on the polarity of solvent so that the population of one of the isomers increases with the polarity of solvent at the expense of the other. The proton NMR spectra of {(h -C5H,R)jlo?(CO) L) (L=thiocamphor, R=H,CH,;R=H and L=4-ethoxythiobenzophenone) at low temperature ("—^O c) show that one of the two isomers generally present in solution is overwhelmingly in larger in proportion in solid state than the other one. The population of the major and minor isomers respectively decrease and increase as the temperature is raised or the mixture is left to equilibrate. This property has made it possible to obtain both kinetic and thermodynamic data. Also the single crystal structure of {h -C,-Hc)Mo,7(CO),L} (L=thiocamphor) has been obtained and the Mo-Mo and C-S bondlengths are found to be 3.145A and 2.769& respectively. In addition to the use of X-ray data characterisation of complexes has been done by utilisation of infrared spectroscopy and, proton and carbon-13 NMR spectroscopy as well as elemental analysis wherever and whenever possible and necessary.