PENTAPHOSPHINE-COMPLEXES OF COBALT(II) AND HYDRIDOPENTAPHOSPHINE-COMPLEXES OF COBALT(III) WITH SECONDARY PHOSPHINES

The secondary phosphines HP(C2H5)2, HP(CH3)Ph and HP(C2H5)Ph react with Co(BF4)2·6H2O to yield cationic pentaphosphine derivatives, which have been obtained in the solid state in two forms of different color. The red [Co(HPR2)5](BF4)2 are truly five-coordinate (low-spin) complexes. whereas the green Co(HPR2)5]2+ moieties, which have C4v symmetry, are probably weakly coordinated in the sixth positon with a water molecule or a tetrafluoroborate ion. In common organic solvents the green forms convert immediately into the red. Some chemical properties of the [Co(HPR2)5]2+ cations have been investigated and the preparation of a few hydrido-derivatives of cobalt(III) of the type [CoH(HPR2)5](BF4)2 is reported. © 1979.