An early–late transition metal hybrid analogue of hexaborane(12)

Abstract

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.