Insertion of CS₂ into a metal acetylide bond and conversion of the bonding mode of S₂CC≡CPh from η² to η³

Abstract

Photolysis of a benzene solution containing [(L)Mo(CO)₃(C≡CPh)] (L=η⁵-C₅H₅ 1; η⁵-C₅Me₅ 2) and CS₂ leads to the formation of dithiopropiolato containing complexes, [(L)Mo(CO)₂(η²-S₂CC≡CPh)] (L=η⁵-C₅H_{5 4}; L=η⁵-C₅Me₅ 5). In presence of air, [(η⁵-C₅H₅)Mo(CO)₃(C≡CPh)] reacts with CS₂ to give 4 as the major and [(η⁵-C₅H₅)Mo(O)(η³-S₂CC≡CPh)] (6) as minor products. Similarly, [(η⁵-C₅Me₅)Mo(CO)₃(C≡CPh)] reacts with CS₂ under aerobic conditions to give compound 5 along with [(η⁵-C₅Me₅)Mo(O)(η³-S₂CC≡CPh)] (7) as minor product. When solutions of 4 or 5 are photolysed under a constant purge of air, 4 gives 6, and 5 gives 7 in high yields. Room temperature stirring of 5 with [W(CO)₅(THF)] forms [η⁵-C₅Me₅)Mo(CO)₂CS₂{W(CO)₅}₂C≡CPh] (9). All new compounds have been characterised by IR and ¹H-NMR spectroscopy and the structures of 4, 6, 7 and 9 have been established crystallographically.