A COMPARISON OF THE REACTIONS OF PPH(2)CH(2)SR (R=ME, PH) WITH ALKYNE-BRIDGED DICOBALT CARBONYL-COMPLEXES AND WITH AN IRON DICOBALT MU(3)-THIOXO CARBONYL COMPLEX

The reactions of Ph(2)PCH(2)SR (R = Me, Ph) in toluene with the dicoba lt complexes [Co-2(mu-R(1)CCR(2))(CO)(6)] (R(1) = R(2) = CO(2)Me and R (1) = H, R(2) = CO(2)Me) give the monosubstituted complexes [Co-2(mu-R (1)CCR(2))(CO)(5)PPh(2)CH(2)SMe] 1 and [CO2(mu-R(1)CCR(2))(CO)(5)PPh(2 )CH(2)SPh] 2. On heating 1 and 2 in toluene solution, loss of CO leads to the bridged species [Co-2(mu-R(1)CCR(2))(mu-PPh(2)CH(2)SMe)(CO)(4) ] 3 and [Co-2(mu-R(1)CCR(2))(mu-PPh(2)CH(2)SPh)(CO)(4)] 4. This transf ormation is readily reversed by treatment of 3 and 4 with CO, showing the Co-S bond in these complexes to be relatively weak. Similar reacti ons of Ph(2)PCH(2)SR (R = Me, Ph) with [Co2Fe(mu(3)-S)(CO)(9)], howeve r, give only the ligand bridged species [Co2Fe(mu(3)-S)(mu-Ph(2)PCH(2) SR)(Co)(7)] (R = Me 5 and R = Ph 6). Treatment of 5 and 6 with CO caus es cleavage of the Co-S bond but, in contrast to 3 and 4, the ligand b ridged species readily reform when the CO purge ceases. The structures of 3a and 6 have been confirmed by single-crystal X-ray analysis.