Vanadium(II)-diamine complexes: synthesis, UV-Visible, infrared, thermogravimetry, magnetochemistry and INDO/S characterisation

Abstract

The synthesis, spectroscopic characterisation and reactivity of a series of vanadium(II) complexes, [VCl2(diamine)2] (diamine = dmeda: N,N'-dimethylethane-1,2-diamine, deeda: N,N'diethylethane-1,2-diamine, tmeda: N,N,N',N'-tetramethylethane-1,2-diamine, dieda: N,N'diisopropylethane-1,2-diamine, teeda: N,N,N',N'-tetraethylethane-1,2-diamine, dtbeda: N,N'-ditert-butylethane-1,2-diamine and dfeda: N,N'-diphenylethane-1,2-diamine) are reported. Some of these complexes can be converted into the trinuclear cation [V3(µCl)3(µ3Cl)2(diamine) 3]+ through the reaction with [V2(µ-Cl)3(thf)3]+ under mild conditions. The compounds were characterised by microanalysis, positive ion FAB mass spectrometry, UVvisible and infrared spectroscopies, thermogravimetric analysis and magnetic moment measurements in the solid state. We characterised fully by single-crystal X-ray diffraction analysis the complex [VCl2(deeda)2]. The stability of [VCl2(diamine)2] as they vary with the different diamines is correlated with crystal field and infrared parameters along with decomposition temperatures and the calculated molecular orbital energies. We also presented a new synthetic route to prepare [V3(µ-Cl)3(µ3-Cl)2(diamine) 3]+ which allows a better control of the reaction pathway, avoiding the formation of undesired redox reaction products.

Keywords

• vanadium(II) diamine complexes
• crystal field analysis
• X-ray crystal structure
• infrared spectroscopy
• thermochemistry