| Summary: | In an attempt to isolate boron-containing tri-niobium polychalcogenide species, we have carried out prolonged thermolysis reactions of [Cp*NbCl<sub>4</sub>] (Cp* = <i>ɳ</i><sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>) with four equivalents of Li[BH<sub>2</sub>E<sub>3</sub>] (E = Se or S). In the case of the heavier chalcogen (Se), the reaction led to the isolation of the tri-niobium cubane-like cluster [(NbCp*)<sub>3</sub>(<i>μ</i><sub>3</sub>-Se)<sub>3</sub>(BH)(<i>μ</i>-Se)<sub>3</sub>] (<b>1</b>) and the homocubane-like cluster [(NbCp*)<sub>3</sub>(<i>μ</i><sub>3</sub>-Se)<sub>3</sub>(<i>μ</i>-Se)<sub>3</sub>(BH)(<i>μ</i>-Se)] (<b>2</b>). Interestingly, the tri-niobium framework of <b>1</b> stabilizes a selenaborate {Se<sub>3</sub>BH}<sup>−</sup> ligand. A selenium atom is further introduced between boron and one of the selenium atoms of <b>1</b> to yield cluster <b>2</b>. On the other hand, the reaction with the sulfur-containing borate adduct [LiBH<sub>2</sub>S<sub>3</sub>] afforded the trimetallic clusters [(NbCp*)<sub>3</sub>(<i>μ</i>-S)<sub>4</sub>{<i>μ</i>-S<sub>2</sub>(BH)}] (<b>3</b>) and [(NbCp*)<sub>3</sub>(<i>μ</i>-S)<sub>4</sub>{<i>μ</i>-S<sub>2</sub>(S)}] (<b>4</b>). Both clusters <b>3</b> and <b>4</b> have an Nb<sub>3</sub>S<sub>6</sub> core, which further stabilizes {BH} and mono-sulfur units, respectively, through bi-chalcogen coordination. All of these species were characterized by <sup>11</sup>B{<sup>1</sup>H}, <sup>1</sup>H, and <sup>13</sup>C{<sup>1</sup>H} NMR spectroscopy, mass spectrometry, infrared (IR) spectroscopy, and single-crystal X-ray crystallography. Moreover, theoretical investigations revealed that the triangular Nb<sub>3</sub> framework is aromatic in nature and plays a vital role in the stabilization of the borate, borane, and chalcogen units.
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