Synthesis and properties of the bis(µ-thiosulphato-S)-bis(dinitrosylferrate)(2–) anion. Crystal and molecular structure of bis[bis(triphenylphosphoranylidene)-ammonium] bis(µ- thiosulphato-S)-bis(dinitrosylferrate)

Abstract

Salts of the bis(µ-thiosulphato-S)-bis(dinitrosylferrate)(2–) anion [Fe2(S2O3)2(NO)4]2– can be prepared by reaction of iron(II)/thiosulphate mixtures either with nitric oxide or with sodium nitrite: the preparation using nitrite provides a convenient route to the 15N labelled anion [Fe2(S2O3)2(15NO)4]2–. The anion reacts readily with thiols RSH to provide good yields of [Fe2(SR)2(NO)4]. Crystals of [N(PPh3)2]2[Fe2(S2O3)2(NO)4] are triclinic, a= 10.999(5), b= 12.748(4), c= 14.020(7)A, α= 67.13(4), β= 83.31(4), γ= 93.87(3)°, space group P with Z= 1: the structure was solved using diffractometer data and refined to an R value of 0.034. The anion lies across a centre of inversion, and hence adopts the trans conformation. The 15N n.m.r. spectrum of [Fe2(S2O3)2(15NO)4]2– shows the presence of only the trans conformer in solution, and that upon exposure to air [Fe2(S2O3)2(15NO)4]2– is readily converted into [Fe4S3(15NO)7]–.