Four- and five-coordinate high-spin iron(II) complexes bearing bidentate soft/hard SN ligands based on 2-aminopyridine

Several new coordinatively unsaturated iron(II) complexes of the types [Fe(SNR-Ph)X2] (X = Cl, Br; R = H, Me, Et) and the dimeric complex [Fe(SNH–Ph)(μ-Cl)Cl]2 containing bidentate N-(2-pyridyl)amino-diphenylphosphine sulfides were prepared and characterized by various methods including X-ray crystallography, 57Fe Mössbauer spectroscopy, SQUID magnetometry, ESI-MS and DFT calculations. All complexes exhibit magnetic moments very close to 4.9 μB reflecting the four unpaired d-electrons. In solution, as revealed by ESI MS studies, all compounds appear to be labile and complexes [Fe(SNR-Ph)X2] seem to be in equilibrium with solvated FeX2, free ligand, and the five-coordinate cationic complexes [Fe(SNR-Ph)2X]+. The latter are the most prominent species in the ESI mass spectra. Despite their relatively low formal electron count all iron complexes were inert towards the addition of carbon monoxide.

Graphical abstractSeveral new coordinatively unsaturated monomeric iron(II) complexes of the types [Fe(SNR-Ph)X2] (X = Cl, Br; R = H, Me, Et) and the dimeric complex [Fe(SNH–Ph)(μ-Cl)Cl]2 containing bidentate N-(2-pyridyl)amino-diphenylphosphine sulfides were prepared and characterized by X-ray crystallography, 57Fe Mössbauer spectroscopy, SQUID magnetization studies, ESI-MS and DFT calculations.Figure optionsDownload full-size imageDownload as PowerPoint slide