Iron and ruthenium derivatives of cyclophosphazenes coordinated through nitrile spacer ligands

Abstract

N 3P 3(O–C 6H 4– t Bu) 5Cl reacts with 4-hydroxybenzylcyanide in acetone in the presence of K 2CO 3, to give the cyanide ligand N 3P 3(O–C 6H 4– t Bu) 5(O–C 6H 4–CH 2–CN) ( 1). The monofunctionalized cyclotriphosphazene, N 3P 3(O–C 6H 4– t Bu) 5(O–C 6H 4–CH 2–CN), reacted with CpFe(dppe)I and with CpRu(PPh 3) 2Cl in the presence of NH 4PF 6 and in CH 3OH as solvent to give the monocationic complexes [N 3P 3(O–C 6H 4– t Bu) 5(O–C 6H 4–CH 2CN) Fe(Cp)dppe]PF 6 ( 2) and [N 3P 3(O–C 6H 4– t Bu) 5(O–C 6H 4–CH 2–CN)·Ru(Cp)(PPh 3) 2] PF 6 ( 3), respectively. Electrochemical as well as chemical oxidation of ( 2) and ( 3) with NOBF 4 yield the stable dicationic species ( 2) + and ( 3) +. Electrochemical as well as spectroscopic data suggest that ligand ( 1) behaves like a nitrile ligand. The small influence of the cyclophosphazene ring upon coordination is attributed to the long length of the organic spacer groups. An exponential dependence of Δ 31P coord with the spacer length was found for several organometallic derivatives of cyclophosphazene.