Complexes with M-P-H Bonds

The first phosphine complex, HjP TiQ4, was discovered by Rose [1] in 1832. Phosphine (PHj) complexes are, however, relatively uncommon and examples containing only PHj ligands attached to the metal atom are rare. Some representative compounds are 

Ligand replacement is the usual method of preparation of PH3 complexes (8.166). This equation indicates that PH3 is a better n acceptor than PPhj. Under the action of UV, the breakdown of M-CO bnt not M-PH3 bonds takes place (8.167). 

Nickel tetraphosphine can be prepared from nickel cyclooctadiene at low temperatures (8.168), but it is unstable and decomposes at -30°C. 

Crystalline Co(PH3)j(CO)3 has been shown by x-ray diffraction to contain molecules with 3 m synunetry. There is sixfold coordination of the metal atom with the phosphine lying in cw positions (8.169c). 

The molybdenum carbonyl monophosphine complex will react with potassium phosphide at 0°C to give eventually a bridged phosphide complex (8.170). The existence of a number of P-PH2 bridged complexes has now been demonstrated, for example, (8.171) [4]. 

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