In protic solvents, K+[HFe(CO)3P]− derivatives are readily protonated to generate
the dihydrides H2Fe(CO)3P which, depending on the reaction temperature, either
(i) evolve by loss of H2 to generate the coordinatively unsaturated ‘‘Fe(CO)3P’’
species which react further with an excess ligand to give the disubstituted
Fe(CO)3P2 derivatives, or (ii) evolve by loss of CO to generate the coordinatively
unsaturated H2Fe(CO)2P which react with an excess ligand to give the corresponding
dihydrides H2Fe(CO)2P2. In most cases the dihydrides H2Fe(CO)2P2 may react
further if an excess of P is present to yield the corresponding trisubstituted
Fe(CO)2P3 derivatives. A generalized reaction pathway has been established
(Scheme 4).