Preparation, crystal structures and spectroscopic properties of vanadium(iii) complexes with [V–O–V]4+ cores

Abstract

Dinuclear vanadium(III) complexes, [V₂(μ-O)(phen)₄Cl₂]Cl₂·2Me₂CO (1) and [V₂(μ-O)(dpya)₄Cl₂]Cl₂ (2) [phen = 1,10-phenanthroline; dpya = bis(2-pyridyl)amine], have been synthesized from the reaction of VCl₃ or VCl₃(THF)₃ with bidentate nitrogenous ligands. The ligand substitution reaction between NaNCS and 2 yields a brown dinuclear complex, [V₂(μ-O)(dpya)₃(NCS)₄]·2THF (3), in which each vanadium ion has a different coordination environment, and an orange mononuclear complex, [V(dpya)(NCS)₄]·(Hdpya)·THF (4). Complexes 1–3 contain singly bridged [V–O–V]⁴⁺ cores. From the temperature dependence of the magnetic susceptibilities, weak magnetic interactions are observed for 1–3. UV-Vis and resonance Raman spectra of these complexes are described. The ¹H NMR spectrum of 1, in which two vanadium ions are coupled antiferromagnetically, and those of its analogs have been measured and assigned.