POLYFLUOROTHIOLATE DERIVATIVES OF RHODIUM(I) - CRYSTAL AND MOLECULAR-STRUCTURE OF [RH(MU-SC6HF4)(C8H12)]2

The thiolato-bridged dinuclear compounds [Rh(mu-SR)(COD)]2, where R = p-C6HF4 (1), p-C6H4F (2) and CF3 (3), are obtained from the chloro-bridged analogue by ligand exchange. Compound (1) crystallizes in the space group P1 with a = 9.740(3) angstrom, b = 11.642(4) angstrom, c = 13.997(6) angstrom, alpha = 103.87(3)-degrees, beta = 106.98(3)-degrees and gamma = 105.10(2)-degrees; z = 2. In this dinuclear molecule both Rh atoms have a square planar coordination sharing one edge, namely the two sulphur bridging atoms. The Rh-Rh separation of 2.96 angstrom is consistent with at most a very weak metal-metal interaction. Upon addition of CO the dimeric [Rh(mu-SR)(CO)2]2 (4), (5) and (6) are obtained, but addition of PPh3 affords the monomeric species [Rh(SR)(PPh3)(COD)] (7), (8) and (9). Reactions of the dimeric tetracarbonyl derivatives with PPh3 vary with the nature of R; [Rh(mu-SR)(PPh3)(CO)]2 is obtained when R = p-C6H4F (10) and CF3 (11) but monomeric [Rh(SR)(PPh3)(CO)2] (12) is produced when R = p-C6HF4. The latter mononuclear compounds, with R = p-C6H4F (13) and CF3 (14), are also formed by reaction of [Rh(SR)(PPh3)(COD)] with CO.