Synthesis and Structural Characterization of a Dimeric Cobalt(I) Homoleptic Alkyl and an Iron(II) Alkyl Halide Complex


The homoleptic cobalt(I) alkyl [Co{C(SiMe2Ph)3}] 2 (1) was prepared by reacting CoCl2 with [Li{C(SiMe 2Ph)3}(THF)] in a 1:2 ratio. Attempts to synthesize the corresponding iron(I) species led to the iron(II) salt [Li(THF) 4][Fe2(-Cl)3{C(SiMe2Ph) 3}2] (2). Both 1 and 2 were characterized by X-ray crystallography, UV-vis spectroscopy, and magnetic measurements. The structure of 1 consists of dimeric units in which each cobalt(I) ion is ?-bonded to the central carbon of the alkyl group -C(SiMe2Ph)3 and ?-bonded to one of the phenyl rings of the -C(SiMe2Ph)3 ligand attached to the other cobalt(I) ion in the dimer. The structure of 2 features three chlorides bridging two iron(II) ions. Each iron(II) ion is also ?-bonded to the central carbon of a terminal -C(SiMe2Ph) 3 anionic ligand. The magnetic properties of 1 reveal the presence of two independent cobalt(I) ions with S = 1 and a significant zero-field splitting of D = 38.0(2) cm-1. The magnetic properties of 2 reveal extensive antiferromagnetic exchange coupling with J = -149(4) cm-1 and a large second-order Zeeman contribution to its molar magnetic susceptibility. Formation of the alkyl 1 and the halide complex 2 under similar conditions is probably due in part to the fact that Co(II) is more readily reduced than Fe(II).




National Science Foundation (U.S.)


Financial support by National Science Foundation (U.S.), Grant No. CHE-1263760

Keywords and Phrases

Carbon; Chlorine Compounds; Cobalt; Exchange Coupling; Ions; Iron Compounds; Ligands; Lithium; Magnetic Susceptibility; Metal Halides; Ultraviolet Visible Spectroscopy; X Ray Crystallography; Alkyl Halides; Anionic Ligands; Antiferromagnetic Exchange Coupling; Halide Complexes; Structural Characterization; UV-vis Spectroscopy; Zeeman Contribution; Zero-field Splittings; Cobalt Compounds

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© 2014 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Apr 2014