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

Photolysis of a benzene solution containing [(L)Mo(CO)3(CCPh)] (L=η5-C5H51; η5-C5Me52) and CS2 leads to the formation of dithiopropiolato containing complexes, [(L)Mo(CO)2(η2-S2CCCPh)] (L=η5-C5H54; L=η5-C5Me55). 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.