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Electron Precise Group 5 Dimetallaheteroboranes [{CpV(μ-EPh)}<inf>2</inf>{μ-η<sup>2</sup>:η<sup>2</sup>-BH<inf>3</inf>E}] and [{CpNb(μ-EPh)}<inf>2</inf>{μ- η<sup>2</sup>:η<sup>2</sup>-B<inf>2</inf>H<inf>4</inf>E}] (E = S or Se)
Date Issued
05-02-2018
Author(s)
Chowdhury, Monojit Ghosal
Barik, Subrat Kumar
Saha, Koushik
Kirubakaran, Bakthavachalam
Banerjee, Abhishek
Ramkumar, Venkatachalam
Indian Institute of Technology, Madras
Abstract
Synthesis and structural elucidation of various electron precise group 5 dimetallaheteroboranes have been described. Room temperature reaction of [Cp2VCl2] with Li[BH3(EPh)], generated from the treatment of LiBH4·THF and Ph2E2 (E = S or Se), for 1 h in toluene, followed by thermolysis, led to the formation of bimetallic complexes [{CpV(μ-EPh)}2{μ- η2:η2-BH3E}], 1 and 2 (1: E = S and 2: E = Se), and [{CpV(μ-SePh)}2{μ- η2:η2-BH(OC4H8)Se}], 3. One of the striking features of these compounds is that they represent a rare class of distorted tetrahedral clusters having bridging hydrogens. Evaluating the skeletal electron pairs and bonding types, compounds 1, 2, and 3 may be considered as isoelectronic with our earlier reported [(CpV)2(B2H6)2]. In an attempt to synthesize the Nb analogues of 1-3, room temperature reactions of [CpNbCl4] and Li[BH3(EPh)] (E = S or Se) were carried out that afforded compounds [{CpNb(μ-EPh)}2{μ- η2:η2-B2H4E}], 4 and 5 (4: E = S and 5: E = Se). The solid-state X-ray structures of both 4 and 5 exemplify electronically saturated [M2B3] systems, and their geometries are analogous to that of [(Cp∗MoCl)2B3H7]. For the extension of this work, reaction of [Cp∗TaCl4] (Cp∗ = η5-C5Me5) with Li[BH3(SePh)] was carried out that yielded a tantalaselenaborane cluster [(Cp∗Ta)2(μ-Se)B3H6Se(C6H5)] (6). All the new compounds have been characterized using 1H, 11B{1H}, 13C{1H} NMR, UV-vis absorption, and IR spectroscopy, mass spectrometry, and X-ray diffraction studies.
Volume
57