Co/Fe(alpha-Alkyl-tpdt)(2) (x-): Alkyl-Substituted Cobalt and Iron Bis-dithiolenethiophenic Complexes

Abstract

Tetraphenylphosphonium salts of Co and Fe complexes with alkyl substituted, tert-butyl (tb) and isopropyl (dp), 2,3-thiophenedithiolate (α-tpdt) ligands, namely TPP[Co(α-tb-tpdt)2] (3), TPP2[Fe(α-tb-tpdt)2]2 (4a-b), TPP[Co(α-dp-tpdt)2] (5) and TPP[Fe(α-dp-tpdt)2] (6) were prepared and characterized by cyclic voltammetry, single crystal. X-ray diffraction, magnetic susceptibility measurements and 57Fe Mössbauer spectroscopy Compound 3 and 5 are isostructural with their Au and Ni analogues with a square-planar coordination geometry. Compound 4 presents two polymorphs (4a-b) both showing a Fe(III). The magnetic susceptibility of 3 and 5 show a behavior dominated by antiferromagnetic interactions, with room temperature magnetic moments of 3.40 μB and 3.36 μB, respectively, indicating that these square-planar Co(III) complexes assume an intermediate spin electronic configuration (S=1) as supported by multiconfigurational DFT calculations.