Novel Neutral Zirconaborane [(Cp₂Zr)₂B₅H₁₁]: An arachno-B₃H₉ Analogue (Cp = η⁵‑C₅H₅)

The first example of a homometallic neutral zirconaborane, [(Cp₂Zr)₂B₅H₁₁], 1, has been prepared through the thermolysis of [Cp₂Zr­(BH₄)₂], generated from the fast metathesis reaction of [Cp₂ZrCl₂] and LiBH₄·thf with BH₃·thf. The solid-state structure of 1 shows an open geometry with a planar B₃ ring. The bonding between the Zr center and the central B₃ ring was studied computationally by DFT methods, and based on the combined experimental and computational results compound 1 can be defined as a metal-stabilized arachno-B₃H₉. Further, in an attempt to synthesize a hybrid analogue of 1 by introducing two electron fragments into arachno-[(Cp₂Zr)­(Cp*Ir)­B₄H₁₀], 2, we have performed the reaction of 2 with [Ru₃(CO)₁₂]. However, the reaction led to the formation of a hybrid metallaborane, [(Cp*Ir)­{Ru₃(CO)₈}­B₄H₁₀], 3.