Synthesis and structural characterization of group 5 dimetallaheteroboranes

Abstract

Treatment of group 5 metal polychlorides such as [Cp_nMCl_4−x] (M = Nb: n = 1, x = 0; M = V: n, x = 2), (Cp = η⁵−C₅H₅) with [LiBH₄·THF] followed by thermolysis in presence of diphenyl dichalcogenide ligands, E₂Ph₂ (E = Se or Te) yielded dimetallaheteroborane clusters [(CpNb)₂BH(Se)₄], 1 and [(CpV)₂B₃H₉(μ₃-Te)], 2 in modest yields. Compound 1 can be considered as an edge fused cluster in which a trigonal bipyramidal unit [Nb₂Se₂B] has been fused with a tetrahedral core [Nb₂Se₂] by means of a common [Nb₂] edge. Compound 2 can be described as a dimetallaheteroborane built from two edge-fused V₂B₂ tetrahedra, in which one of the BH3 units is replaced by an isoelectronic Te ligand. All the compounds have been characterized by mass spectrometry, ¹H, ¹¹B, ¹³C, ⁵¹V and 77Se NMR spectroscopy. In addition the geometry of compound 1 has been established by crystallographic analysis.