391613-48-2Relevant academic research and scientific papers
Formation of triniobocene cationic and neutral mononiobocene species as a function of solvent in the reaction of Cp2Nb{(μ-H)2BR2} (R2 = C4H8, C5H10, C8H14) with B(C6F5)3
Liu, Shengming,Liu, Fu-Chen,Renkes, Gordon,Shore, Sheldon G.
, p. 5717 - 5723 (2008/10/08)
Reactions of the niobocene cyclic organohydroborates Cp2Nb{(μ-H)2BR2} (R2 = C4 H8, C5H10, C8H14), with B(C6F5)3 in the poorly coordinating solvent toluene and in the coordinating solvent diethyl ether give different products. In toluene, the salt [Cp2Nb(μ-H)(η5-η1-C5 H4)-Nb (η5-η1-C5H4)2 Nb{(μ-H)(η5-C5H4B (C6F5)2)}]+[HB(C6 F5)3]-1, 1, which contains a triniobocene cation, is formed. On the other hand in diethyl ether, the reaction of Cp2Nb{(μ-H)2BR2} with B(C6F5)3 produces the covalent complex CpNb(C6F5){(μ-H) (η5-C5H4B(C6 F5)2)}, 2. In the formation of these compounds NbIII is oxidized to NbIV. Upon the basis of ESR spectra, 1 and 2 are paramagnetic, each with one unpaired electron. The structures of 1 and 2 were determined by single-crystal X-ray analysis. Complex 2 forms weak adducts in the solvents THF and pyridine. The Nb-H-B bridge is cleaved at the Nb-H site to form CpNb(C6F5)-(L) {η5-C5H4B(H)(C6 F5)2} (L = THF, pyridine). In pyridine, a second adduct in much smaller yield is also formed, CpNb(C6F5)(H){η5-C5H4 B(Py)(C6F5)2}, with the Nb-H-B bridge being cleaved at the H-B site.
