Synthesis and characterization of diruthenaborane analogues of pentaborane(11) and hexaborane(10)

In an attempt to synthesize expanded-cage metallaheteroboranes containing heavier chalcogen atoms, the reaction of diruthenaborane analogue of pentaborane(9), nido-[1,2-(Cp*RuH)2B3H7] (1) with phenyl-chalcogenoborates Li[BH3(EPh)] (E = S, Se or Te) was carried out. Thermolysis of nido-1 with Li[BH3(SPh)] led to the formation of the dimetalla-pentaborane(11) analogue arachno-[(Cp*Ru)2B3H8(SPh)] (2). In parallel to the formation of 2, the reaction also yielded three B-H functionalized compounds, namely [(Cp*Ru)2B4H7(Ph)] (3), [(Cp*Ru)2B4H7(Cl)] (4) and [(Cp*Ru)2B4H6(SPh)(Cl)] (5). On the other hand, reaction of 1 with Li[BH3(SePh)] led to the formation of the diruthenium analogue of hexaborane(10) nido-[(Cp*Ru)2B4H9(SePh)] (6), whereas Li[BH3(TePh)] yielded the capped nido-pentagonal-pyramidal [(Cp*Ru)2B4H6Te] (7). Compound 7 is a rare ruthenaborane cluster containing a heavier chalcogen element (Te). All the compounds were characterized by mass spectrometry and 1H, 1H{11B}, 11B{1H} and 13C{1H}NMR spectroscopy. The solid state X-ray structures of all the compounds were unequivocally established by crystallographic analysis. Additionally, the electronic properties of compound 2 were analyzed.