THE CHEMISTRY OF HETERO-ALLENE AND -ALLYLIC DERIVATIVES WITH RHODIUM I. THE REACTIONS OF RHODIUM(I)-HETERO-ALLYLIC COMPOUNDS WITH HETERO-ALLENES; B. CARBON DISULFIDE

Article abstract of DOI:10.1016/S0022-328X(00)82814-4

The rhodium(I) complexes Rh(PPh3)2, in which represents an uninegative unsaturated heteroallylic bidentate ligand, coordinating via two of the three heteroatoms (X, Y, Z = P, S or N), react at elevated temperature with an excess of the hetero-allene S=C=S to give the rhodium(I)thiocarbonyl complexes Rh(CS)IPPh3).In the initial step a first CS2 molecule is coordinated side-on by one of the C=S double bands.Subsequent reactions can be blocked at this stage by addition of pyridine, resulting in RhCl(η²-CS2)(PPh3)(py)2.The formation of the CS complexes occurs in two ways.Either by direct sulfur abstraction from the Rh^I(η²-CS2) complex by PPh3 or by a dimerisation of two CS2 molecules and elimination of a CS moiety, resulting in a Rh^III-thiocarbonyl-trithiocarbonato complex, immediately followed by demolition of the trithiocarbonato-CS3^2- fragment by PPh3 to SPPh3 and CS2.Complexes containing a CS3^2- fragment, but no CS moiety, can also be identified by IR measurements.These products may be formed in a sidereaction upon elimination of CS.