Iron, cobalt and vanadium complexes of the N(CH2CH2S)33− ligand with chloride, azide, cyanide and carbonyl co-ligands

Abstract

Reaction of [Fe(acac)₃], Et₄NCl and N(CH₂CH₂SH)₃ (NS₃H₃) in MeCN gave [Et₄N][FeCl(NS₃)] 1 and metathesis the azide [Et₄N][Fe(N₃)(NS₃)] 2, but reaction of [Fe(acac)₃], R₄NOAc and NS₃H₃ in MeCN gave [R₄N][Fe₄(NS₃)₃] (R = Et, 3; Me, 4). Complex 1 is reduced under various conditions giving R′[Fe(NS₃)] (R′ = Et₄N, 5; Tl, 6; N₂H₅, 7) which probably contain sulfur-bridged [{Fe(NS₃)}_n]ⁿ⁻ anions. Under CO, 1 is reduced to the paramagnetic [Et₄N][Fe(NS₃)(CO)] 8 from which Tl[Fe(NS₃)(CO)] 9 may be made by metathesis. Compound 8 reacts with metal chlorides in acetonitrile giving trinuclear [M{Fe(NS₃)(CO)}₂-S,S′] (M = Fe, 10; Co, 11). The above complexes were characterised by microanalysis, IR and Mössbauer spectra and magnetic measurements; crystal structure determinations were carried out on 1, 2, 8, 10, and 11. The properties of the anions of 1 and 8 and of the hypothetical anions [Fe(NS₃)]⁻ and [Fe(N₂)(NS₃)]⁻ have been investigated by density functional theory calculations. Compounds 8 and 10 have ν(CO) in the range 1960–1880 cm⁻¹ and model aspects of carbon monoxide binding to the cofactor of nitrogenase. Related cyanide complexes [Et₄N][M(NS₃)(CN)] (M = Co, 12; V, 13) have been characterised, 12 by X-ray analysis.