Synthesis and Structural Characterization of New Divanada‐ and Diniobaboranes Containing Chalcogen Atoms

The reaction of Cp_nMCl_4?x] (M=V: n=2, x=2; M=Nb: n=1, x=0; Cp=η⁵‐C₅H₅) with LiBH₄ ? THF followed by thermolysis in the presence of dichalcogenide ligands E₂R₂ (E=S, Te; R=2,6‐(tBu)₂‐C₆H₂OH, Ph) and 2‐mercaptobenzothiazole (C₇H₅NS₂) yielded dimetallaheteroboranes {CpV(μ‐TePh)}₂(μ₃‐Te)BH ? thf] ( 1 ), (CpV)₂(BH₃S)₂] ( 2 ), (CpNb)₂B₄H₁₀S] ( 3 ), (CpNb)₂B₄H₁₁S(tBu)₂C₆H₂OH] ( 4 ), and (CpNb)₂B₄H₁₁TePh] ( 5 ). In cluster 1 , the V₂BTe atoms define a tetrahedral framework in which the boron atom is linked to a THF molecule. Compound 2 can be described as a dimetallathiaborane that is built from two edge‐fused V₂BS tetrahedron clusters. Cluster 3 can be considered as an edge‐fused cluster in which a trigonal‐bipyramidal unit (Nb₂B₂S) has been fused with a tetrahedral core (Nb₂B₂) by means of a common Nb₂ edge. In addition, thermolysis of an in‐situ‐generated intermediate that was produced from the reaction of Cp₂VCl₂] and LiBH₄ ? THF with excess BH₃ ? THF yielded oxavanadaborane (CpV)₂B₃H₈(μ₃‐OEt)] ( 6 ) and divanadaborane cluster (CpV)₂B₅H₁₁] ( 7 ). Cluster 7 exhibits a nido geometry with C_2v symmetry and it is isostructural with (Cp*M)₂B₅H_9+n] (M=Cr, Mo, and W, n=0; M=Ta, n=2; Cp*=η⁵‐C₅Me₅). All of these new compounds have been characterized by ¹H NMR, ¹¹B NMR, and ¹³C NMR spectroscopy and elemental analysis and the structural types were established unequivocally by crystallographic analysis of compounds  1 – 4 , 6 , and 7 .