Preparation and characterization of an unusual tetracobalt-complex; X-ray crystal structure of [Co2(CO)5{μ-P,P(μ-PPh2CCPPh2)}][Co2(CO)4{μ-P-(μ-PPh2CCPPh2)}]

The reaction of bis(diphenylphosphino)acetylene(DPPA) with Co2(CO)8 in toluene at 80 °C for 24 h resulted in an alkyne-bridged, diphosphine-chelated tetracobalt-complex, [Co2(CO)5{μ-P,P-(μ-PPh2CCPPh2)}][Co2(CO)4{μ-P-(μ-PPh2CCPPh2)}] 3. The X-ray structural studies of 3 reveals that it can be regarded as a dimerized form of two DPPA bridged dicobalt complex, [Co2(CO)6(μ-PPh2CCPPh2)] 1.