Ligand Effects on the Formation of Imino Complexes

NHz (PPN), PhzPCHzCH(CH3)NHz (PN-21, and HzN(CHZ)~PP~Z (PN-3) resulted in the formation of [C~F~(P,PJV-PZN)II (lo), [CpFe(P,PJV-PNP)II (1 11, [CpFe(P,PJV-PPN)II (121, [CpFe(CO)(P,N-PN-2)]1 (13), and [CpFe(CO)(PJV-PN-3)11 (141, respectively. Complexes 10 and 12 were easily converted into their corresponding imino complexes [CpFe(P,P,N[CH~C(CHZPP~Z)Z(CH=NHH)~)~I (15) and [C~F~(P,PJV-[P~ZPCHZCH(PP~Z)(CH=NH)]}II (16), respectively, whereas the other complexes resisted such oxidation processes. Substitution of carbonyl by trimethylphosphine in 14 resulted in conversion of the amino function into the corresponding imino group. It appears that strong n-acceptor ligands bound to the metal ion center prevent oxidation. Crystal structures of the imino complexes 15 and 16 and the amino complex 14 were determined. The reasons that 11 does not convert into its corresponding imino complex are also discussed. C H ~ C ( C H ~ P P ~ Z ) Z ( C H ~ N H ~ ) (Pz ), PhZPCH&H(NH&H2PPhz (PNP), Ph2PCH&H(PPh2)CHz-