An Early–Late Transition Metal Hybrid Analogue of Hexaborane(12)

Metal assisted borane condensation method has been employed for the preparation of novel metallaborane cluster containing group 4 metal. Pyrolysis of [Cp*IrB3H9], 1, with in situ generated zirconium bisborohydrate [Cp2Zr­(BH4)2], produced from the fast metathesis reaction of [Cp2ZrCl2] and LiBH4, and excess of BH3·THF yielded arachno-[(Cp2Zr)­(Cp*Ir)­B4H10], 2, in 56% yield. Compound 2 constitutes the first crystallographic structure determination of hexaborane(12) metal analogue containing zirconium. The observed geometry of 2 can be generated from a dodecahedron by removing two vertices and an edge. Anticipating a straight metal fragment substitution/addition reaction, mild thermolysis of 2 with [Fe2(CO)9] was carried out. However, the reaction led to the formation of known trimetallic [Cp*IrFe2(CO)9] cluster via cluster degradation. In addition, density functional theory (DFT) calculations have been carried out for 2 and other hypothetical early–late combinations of hexaborane(12) metal analogues to reveal the electronic structures.