Synthesis and Structural Characterization of Compounds Containing the [Zr₆Cl₁₈H₅]^3- Cluster Anion. Determination of the Number of Cluster Hydrogen Atoms

Abstract

Reduction of ZrCl4 with HSnBu3 followed by addition of [R4A]Cl resulted in the formation of [R4A]3[Zr6Cl18H5] (2a, R = Ph, A = P; 2b, R = n-Pr, A = N; 2c, R = Et, A = N). Six zirconium atoms are arranged as an octahedron with one Cl atom terminally coordinated to each Zr atom and the other 12 Cl atoms edge-bridging the octahedron. When [Ph4P]I was used, the compound [Ph4P]3[Zr6Cl18-xIxH5] (x = 0.81) (3) was isolated. In compound 3, I atoms occupy only the terminal positions. The number of cluster hydrogen atoms in compounds 2a−c and 3 was established by 1H NMR. The X-ray results are consistent with the five cluster hydrogen atoms being distributed at or slightly outside the centers of all eight triangular faces of the octahedron. Compounds 2a−c and 3 were characterized by X-ray single-crystal diffraction. Compound 2a·3CH2Cl2 crystallized in the triclinic space group P1̄ with cell dimensions (20 °C) of a = 15.993(3) Å, b = 22.237(3) Å, c = 14.670(4) Å, α = 95.31(1)°, β = 112.07(2)°, γ = 82.06(2)°, V = 4784(2) Å3, and Z = 2. Compound 2a crystallized in the tetragonal space group I41/a with cell dimensions (20 °C) of a = 33.196(2) Å, b = 33.196(2) Å, c = 15.236(2) Å, V = 16790(3) Å3, and Z = 8. Compound 2a·4C6H5CH3 crystallized in the triclinic space group P1̄ with cell dimensions (−60 °C) of a = 14.501(5) Å, b = 26.630(9) Å, c = 14.049(5) Å, α = 90.39(3)°, β = 94.19(3)°, γ = 82.59(1)°, V = 5365(3) Å3, and Z = 2. Compound 2b crystallized in the cubic space group Im3̄m with cell dimensions (−60 °C) of a = 15.039(3) Å, b = 15.039(3) Å, c = 15.039(3) Å, V = 3438(1) Å3, and Z = 2. Compound 2c·2.43MeCN crystallized in the orthorhombic space group Pnma with cell dimensions (−100 °C) of a = 21.156(1) Å, b = 24.584(3) Å, c = 11.713(2) Å, V = 6092(1) Å3, and Z = 4. Compound 3·3CH2Cl2·C6H5CH3 crystallized in the monoclinic space group P21/c with cell dimensions (20 °C) of a = 19.786(5) Å, b = 19.071(4) Å, c = 27.397(5) Å, β = 90.22(3)°, V = 10337(4) Å3, and Z = 4