POSSIBLE COOPERATIVE BONDING BETWEEN THE RU-BONDED AND THE S-BONDED SO2 GROUPS IN CPRU(PPH3)(SO2)(S(SO2)-4-C6H4ME)

The complexes CpRu(PPb3)2SR, where R = 4-C6H4Me, 1-C3H7, and CHMe2, react with SO2 to give two types of products; one, CpRu(PPH3)2(S(SO2)R), possesses a labile S-bonded SO2 group, and the other type, CpRu(PPh3)(SO2)(S(SO2)R), possesses both S-bonded and Ru-bonded SO2 groups neither of which are labile. The structure of CpRu(PPh3)(SO2)(S(SO2)-4-C6H5Me) was determined: P2(1)/C, a = 9.954 (2) angstrom, b = 18.423 (5) angstrom, c = 16.111 (4) angstrom, beta = 95.13 (2)-degrees, V = 2942.6 angstrom3, and /Z = 4. During the initial stages of the reaction, complexes with two SO2 groups are favored at low SO2 concentrations, while those with only S-bonded SO2 are favored at high concentrations. This observation and the differences in the relative ease of SO2 loss between the two types of complexes is discussed in terms of cooperativity between the two SO2 groups. This leads to reduced lability of the S-bonded SO2 group when the complex contains a Ru-bonded SO2 ligand (or a CO ligand).