A comparison of the reactions of PPh2CH2SR (R = Me, Ph) with alkyne-bridged dicobalt carbonyl complexes and with an iron dicobalt μ3-thioxo carbonyl complex

Abstract The reactions of Ph 2 PCH 2 SR (R = Me, Ph) in toluene with the dicobalt complexes [Co 2 (μ-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 (μ-R 1 CCR 2 )(CO) 5 PPh 2 CH 2 SMe] 1 and [Co 2 (μ- 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 (μ-R 1 CCR 2 )(μ- PPh 2 CH 2 SMe)(CO) 4 ] 3 and [Co 2 (μ -R 1 CCR 2 )(μ-PPh 2 CH 2 SPh)(CO) 4 ] 4 . This transformation is readily reversed by treatment of 3 and 4 with CO, showing the Co-S bond in these complexes to be relatively weak. Similar reactions of Ph 2 PCH 2 SR (R = Me, Ph) with [Co 2 Fe(μ 3 -S)(CO) 9 ], however, give only the ligand bridged species [Co 2 Fe(μ 3 -S)(μ-Ph 2 PCH 2 SR)(CO) 7 ] (R = Me 5 and R = Ph 6 ). Treatment of 5 and 6 with CO causes cleavage of the Co-S bond but, in contrast to 3 and 4 , the ligand bridged species readily reform when the CO purge ceases. The structures of 3a and 6 have been confirmed by single-crystal X-ray analysis.