A novel cobalt system featuring a Co-P moiety has been synthesized to study its metal-ligand cooperativity. A reversible conversion of a phosphide group to a P-P bond found in a dimeric cobalt(i) complex involves electron transfer between Co and P, in which a single electron transfer is successfully coupled with a redox change in each cobalt ion. Upon coordination of a pi-acidic ligand such as acetonitrile and isocyanide at the cobalt site, the transformation of a dimeric to a monomeric cobalt complex occurs, which involves the migration of a phenolate group. During the conversion, a P-P bond was cleaved and converted to phosphide and phosphinite. Current Co-P metal-ligand cooperativity presented in this work has been explored structurally, spectroscopically and theoretically.