SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF COMPOUNDS CONTAINING THE[ZR6CL18H5](3-) CLUSTER ANION - DETERMINATION OF THE NUMBER OF CLUSTER HYDROGEN-ATOMS

Reduction of ZrCl4 with HSnBu3 followed by addition of [R(4)A]Cl resul ted in the formation of [R(4)A](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 at om 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 i solated. In compound 3, I atoms occupy only the terminal positions. Th e number of cluster hydrogen atoms in compounds 2a-c and 3 was establi shed by H-1 NMR. The X-ray results are consistent with the five cluste r 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.3C H(2)Cl(2) crystallized in the triclinic space group P (1) over bar wit h cell dimensions (20 degrees C) of a = 15.993(3) Angstrom, b = 22.237 (3) Angstrom, c = 14.670(4) Angstrom, alpha 95.31(1)degrees, beta = 11 2.07(2)degrees, gamma = 82.06(2)degrees, V = 4784(2) Angstrom(3), and Z = 2. Compound 2a crystallized in the tetragonal space group I4(1)/a with cell dimensions (20 degrees C) of a = 33.196(2) Angstrom, b = 33. 196(2) Angstrom, c = 15.236(2) Angstrom, V = 16790(3) Angstrom(3), and Z = 8. Compound 2a.4C(6)H(5)CH(3) crystallized in the triclinic space group P (1) over bar with cell dimensions (-60 degrees C) of a = 14.5 01(5) Angstrom, b = 26.650(9) Angstrom, c = 14.049(5) Angstrom, alpha = 90.39(3)degrees, beta = 94.19(3)degrees, gamma = 82.59(1)degrees, V = 5365(3) Angstrom(3), and Z = 2. Compound 2b crystallized in the cubi c space group Im (3) over bar m with cell dimensions (-60 degrees C) o f a 15.039(3) Angstrom, b = 15.039(3) Angstrom, c = 15.039(3) Angstrom , V = 3438(1) Angstrom(3) , and Z = 2. Compound 2c.2.43MeCN crystalliz ed in the orthorhombic space group Pnma with cell dimensions (-100 deg rees C) of a = 21.156(1) Angstrom, b = 24.584(3) Angstrom, c = 11.713( 2) Angstrom, V = 6092(1) Angstrom(3), and Z = 4. Compound 3.3CH(2)Cl(2 ).C6H5-CH3 crystallized in the monoclinic space group P2(1)/c with cel l dimensions (20 degrees C) of a 19.786(5) Angstrom, b = 19.071(4) Ang strom, c = 27.397(5) Angstrom, beta = 90.22(3)degrees, V = 10337(4) An gstrom(3), and Z = 4.