title: Syntheses and structures of Zr4 tetrahedral clusters containing direct Zr-Zr bonds: the missing cluster in the series Zr(n) (n = 2-6).
abstract: The reduction of [(μ(2)-H)( μ(3)-H)(Cp*ZrCl)](4) by excess Na/Hg led to the isolation of the mixed-valence Zr(III)/Zr(IV) Zr(4) cluster [(μ(2)-H)(8)(μ(2)-Cl)(2)(Cp*Zr)(4)], 1, and the Zr(II)/Zr(III) Zr(4) cluster [(μ(2)-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 Zr(4) tetrahedrons containing direct Zr-Zr bonds.
authors.affiliation: Department of Medical Research, Buddhist Tzu Chi General Hospital and General Education Center, Tzu Chi College of Technology, Hualien, 970, Taiwan, ROC.
authors.forename: Hsueh-Hui
authors.initials: HH
authors.lastname: Yang
authors.forename: Chung-Hsien
authors.initials: CH
authors.lastname: Chien
authors.forename: Chien-Chan
authors.initials: CC
authors.lastname: Yang
authors.forename: Fu-Chen
authors.initials: FC
authors.lastname: Liu
authors.forename: Agnes H H
authors.initials: AH
authors.lastname: Chang
authors.forename: Gene-Hsian
authors.initials: GH
authors.lastname: Lee
authors.forename: Shie-Ming
authors.initials: SM
authors.lastname: Peng
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D008968:Molecular Conformation; D015040:Zirconium / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D015040:Zirconium