The reduction of [(μ2-H)( μ3-H)(Cp*ZrCl)]4 by excess Na/Hg led to the isolation of the mixed-valence Zr(III)/Zr(IV) Zr4 cluster [(μ2-H)8(μ2-Cl)2(Cp*Zr)4], 1, and the Zr(II)/Zr(III) Zr4 cluster [(μ2-H)6(Cp*Zr)4], 2. The proton NMR data supports the diamagnetic property of both clusters in solution and the solid state structure of each cluster revealed a distorted tetrahedral skeleton comprised of four Zr atoms and the presence of direct Zr–Zr bonds. The hydride-bridged Zr–Zr bond distances are in the range of 3.0516(6)–3.0585(6) Å in 1 and 3.0525(13)–3.0864(13) Å in 2. The chloride-bridged Zr–Zr distances in 1 are 3.5514(6) and 3.5643(6) Å. The existence of Zr–Zr bonds in both clusters was further confirmed by DFT calculations. 1 and 2 represent the first examples of Zr4 tetrahedrons containing direct Zr–Zr bonds.
Dalton Transactions
- Information Point