Reactions of the heteronuclear alkyne-bridged cobalt–molybdenum complex [(OC)3Co{µ-C2(CO2Me)2}Mo(CO)2(η5-C5H5)] with PPh2H, P2Ph4 and PPh2(SPh)

The complex [(OC)3Co{µ-C2(CO2Me)2}Mo(CO)2(η5-C5H5)]1 reacts preferentially at the Co atom with PPh2H, P2Ph4 and PPh2(SPh) to give initially the mono-substituted products [L(OC)2Co{µ-C2(CO2Me)2}Mo(CO)2(η5-C5H5)][L = PPh2H 2, P2Ph43 or PPh2(SPh)4]. In the case of PPh2H further reaction takes place at the Mo atom to give the bis-substituted product [(HPh2P)(OC)2Co{µ-C2(CO2Me)2}Mo(CO)(η5-C5H5)(PPh2H)]5. Thermolysis of the substituted derivatives 2–5 results in either P–H, P–P or P–S bond cleavage. Thus for 2, the isomeric species [(η5-C5H5)(OC)Mo{µ-C(CO2Me)CH(CO2Me)}(µ-PPh2)Co(CO)2]6 and [(OC)2Co{µ-C(CO2Me)CH(CO2Me)}(µ-PPh2)Mo(CO)(η5-C5H5)]7 are obtained, whereas 3 gives [(OC)2Co{µ-PPh2C(CO2Me)C(CO2Me)}(µ-PPh2)Mo(CO)(η5-C5H5)]8, in which the Co atom is incorporated into a four-membered metallacycle. Thermolysis of 4 gives [(η5-C5H5)(OC)Mo{µ-PPh2C(CO2Me)C(CO2Me)}(µ-SPh)Co(CO)2]9(in which the Mo atom is incorporated into a four-membered metallacycle) and thermolysis of 5 gives [(η5-C5H5)(OC)Mo{µ-C(CO2Me)CH(CO2Me)}(µ-PPh2)Co(CO)(PPh2H)]10. Complex 6 can be converted to 10 by reaction with PPh2H. The crystal structures of compounds 6 and 8 have been determined.

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