(BuN)-Bu-t = VCl2 center dot 1,2-dimethoxoethane, a precursor in the synthesis of binuclear diamagnetic tert-butylimidovanadium(IV) compounds

Syntheses of the paramagnetic tert-butylimidovanadium(IV) complexes (BuN)-B u-t = VCl2 . DME (7), (BuN)-Bu-t = VCl2. 2L (L=1,4-dioxane, thf, PMe3, PEt3 , pyridine) and (BuN)-Bu-t = VBr2. DME are described; the free Lewis acids has been found by mass spectroscopy to be the binuclear compounds [(mu-(NBu )-Bu-t)(2)V2Cl4] und [(mu-(NBu)-Bu-t)(2)V2Br4]. 7 reacts with LIOR, LiOAr a nd LiNR2 forming binuclear diamagnetic tert-butylimidovanadium (IV) compoun ds: [(mu-(NBu)-Bu-t)(2)V2Cl2((OPr)-Pr-i)(2)] (1-8), [(mu-NtBu)(2)V-2(OR)(4) ], [(mu-(NBu)-Bu-t)(2)V2Cl2(Nr)(2)], [(mu-(NBu)-Bu-t)(2)V-2(OAr)(4)] and [( mu-(NBu)-Bu-t)(2)V2Cl2(NR2)(2)]. In additional experiments the complexes [( mu-(NBu)-Bu-t)(2)V-2(CH2CMe3)(2)(OAr)(2)], [(mu-(NBu)-Bu-t)(2)V2Me2(NR2)(2) ], [(mu-NtBu)(2)V2Cl4] and tBuN=V(OAr)(3) has been prepared. All compounds obtained are characterized by spectroscopic methods (MS; H-1, C-13, V-51 NI LIR), [(mu-(NBu)-Bu-t)(2)V2Cl2((NBuSiMe3)-Bu-t)(2)] (21) by single crystal x-ray diffraction. For 18 the presence of cis/trans isomeres was shown by N MR spectroscopy. The V-51 NMR spectra of the binuclear diamagnetic vanadium (IV) compounds are discussed.