Facile synthesis, X-ray analysis, and spectroscopic studies of di-iron propanedithiolate complexes with tris(aromatic)phosphine ligands

Abstract

Three new propanedithiolate-type iron–sulfur complexes containing tris(aromatic)phosphine ligands, [{(μ-SCH₂)₂CH₂}Fe₂(CO)₅L] (L = P(PhOMe-p)₃, 1; P(PhMe-p)₃, 2; P(PhF-p)₃, 3), have been prepared through carbonyl substitution in the presence of Me₃NO. The new complexes 1–3 were characterized by elemental analysis, IR, ¹H, ¹³C{¹H}, and ³¹P{H} NMR spectra. The molecular structures of 1–3 were unequivocally determined by single crystal X-ray diffraction, in which the tris(aromatic)phosphine coordinated to Fe resides in an apical position of the pseudo-square-pyramidal geometry. IR spectroscopy and X-ray crystallographic analysis for 1–3 have indicated that the highly electron rich tris(aromatic)phosphine ligands (where the corresponding electron-donating abilities display the following order of P(PhOMe-p)₃ > P(PhMe-p)₃ > P(PhF-p)₃) result in a considerable red shift of the CO-stretching frequencies and a clear change of the Fe–Fe bond distances in 1–3.

Graphical Abstract

Keywords:

• Iron–sulfur complexes
• Tris(aromatic)phosphine
• Carbonyl substitution
• X-ray analysis
• Spectroscopic study

Funding

This work was financially supported by the National Natural Science Foundation of China [grant number 21301160] and the Natural Science Foundation for Young Scholars of Shanxi Province [grant number 2012021007-4].