CHEMISTRY OF C-TRIMETHYLSILYL-SUBSTITUTED HETEROCARBORANES .17. SYNTHESES, STRUCTURES, AND REACTIVITIES OF BENT-SANDWICH, D(O) ZIRCONACARBORANES OF THE CARBONS ADJACENT C2B4 CARBORANE SYSTEMS

The reaction of ZrCl4 with o-Li(THF)-1-Na(THF)-2-(SiMe(3))-3-(R)-2,3-C 2B4H4(R = SiMe(3), Me, H) in a benzene/THF solvent mixture produced (2 )-4,4',5,5'-Li(THF)-1,1'-commo-Zr(2,3-C2B4H4)(2) (R = SiMe(3) (I), Me (II), H (III)), in 68%, 61%, and 59% yields, respectively. Compound I was found to be resistant to chloride substitution with common alkylat ing agents. Instead, the reaction of I with Me(3)SiCH(2)MgCl in a 1:1 molar ratio in a THF/Et(2)O solvent mixture produced, in 40% yield, th e salt 3'-(SiMe(3))4-1,1-commo-Zr(2,3-C2B4H4)(2)](2).4THF (IV), while a 1:2 molar reaction gave mu-H)(4)Li](mu(3)-Cl)[Mg-(mu(2)-Cl)(THF)(3)] (2)-1, 1'-commo-Zr(2,3-C2B4H4)2 (V), in 65% yield. Ah compounds were c haracterized by chemical analyses, infrared spectroscopy, and H-1,B-11 , and C-13 MMR spectroscopy. Compounds I, II, and V were further chara cterized by Li-7 NMR spectroscopy and I, II, TV, and V by single cryst al X-ray diffraction. Compound I crystallizes as I.THF, in the triclin ic space group P ($) over bar 1, while II, IV, and V crystallized in t he monoclinic space groups P2(1)/c, P2(1)/c, and C2/c, respectively. T he unit cell parameters of I.THF are a = 11.428(3) Angstrom b = 12.140 (3) Angstrom c = 17.685(4) Angstrom alpha = 93.27(2)degrees, beta = 90 .35(2)degrees, gamma 114.91(2)degrees, V = 2220.4(8) Angstrom(3), and Z = 2, while those of II, IV and V are a = 16.928(8), 13.129(2), and 2 5.602 Angstrom b = 16.373(6), 22.429(5), and 22.541(4) Angstrom c = 12 .048(5), 19.217(3), and 24.740(5) Angstrom, beta = 90.37(3), 90.16(2), and 90.17(2)degrees, V = 3339(2), 5660(2), and 14277(5) Angstrom(3), and Z = 4, 2, and 8, respectively. Full-matrix least-squares refinemen ts of I.THF, II, IV, and V converged at R = 0.044, 0.059, 0.051, and 0 .078 and R(w) = 0.057, 0.073, 0.065, and 0.086, respectively.