MONOMERIC ALKYL AND HYDRIDE DERIVATIVES OF ZINC SUPPORTED BY POLY(PYRAZOLYL)HYDROBORATO LIGATION - SYNTHETIC, STRUCTURAL, AND REACTIVITY STUDIES

A series of monomeric four-coordinate monoalkyl zinc complexes [Tp(But)]ZnR ([Tp(But)] = tris(3-tert-butylpyrazolyl)hydroborato ; R = Me, Et) and [Tp(Me2)]ZnMe ([Tp(Me2)] = tris(3,5-dimethylpyrazolyl)hydroborato) has been prepared by metathesis of R(2)Zn with Tl[Tp(But)] and Tl[Tp(Me2)], respectively, while the three-coordinate zinc alkyl derivatives [Bp(But)]ZnR ([Bp(But)] = bis(3-tert-butylpyrazolyl)hydroborato; R = Me, Et, Bu(t)) have been synthesized by the reactions of R(2)Zn with Tl[Bp(But)]. The monomeric zinc hydride derivative [Bp(But)]ZnH has also been prepared by the reaction of ZnH2 with Tl[Tp(But)]. The reactivities of [Tp(But)]ZnH and [Tp(But)]ZnR toward a variety of substrates have been investigated, giving rise to a series of derivatives [Tp(But)]ZnX (X = O2CH, O(2)CMe, C(2)Ph, SH, OSiMe(3), Cl, Br, I). The Zn-C bonds of the three-coordinate complexes [Bp(But)]ZnR (R Me, Et) are cleaved by H2O to give the cyclic hydroxo trimer {[Bp(But)]Zn(u-OH))}3 and by MeCO(2)H to give [Bp(But)]Zn(eta(2)-O(2)CMe). Me(2)CO, MeCHO, and (CH2O)(n), insert into the B-H bond of [Bp(But)]ZnR, in preference to the Zn-R bond, to give the complexes {HB(OR')(3-Bu(t)pz)(2)}ZnR (R' = Me, Et, Pr-i). The molecular structures of[Tp(Me2)]ZnMe, [Tp(Me2)]Zn-2, [Tp(But)]ZnH, [Tp(But)]Zn(eta(1)-O(2)CMe), [Tp(But)]ZnNCS, [Bp(But)]ZnBu(t), and {[Bp(But)]Zn(mu-OH)}3 have been determined by X-ray diffraction. [Tp(Me2)]ZnMe is orthorhombic, Pcmn (No. 62), a = 7.831(2) Angstrom, b = 13.376(4) Angstrom, c = 18.877(4) Angstrom V = 1977 (1) Angstrom(3), and Z = 4. [Tp(Me2)]Zn-2 is triclinic, P ($) over bar 1 (No. 2), a = 8.806(1) Angstrom, b = 10.195(2) Angstrom, c = 10.800 (2) Angstrom alpha = 63.46(2)degrees, beta = 85.11(2)degrees, gamma = 79.63(1)degrees, V = 853(1) Angstrom(3), and Z = 1. [Tp(But)]ZnH is monoclinic, Pn (No. 7), a = 8.262(1) Angstrom, b = 15.465(2 Angstrom, c = 9.696(2) Angstrom, beta = 100.76(2)degrees, V = 1217(1) Angstrom(3), and Z = 2. [Tp(But)]Zn(eta(1)-O(2)CMe) is orthorhombic, P2(1)cn (No. 33), a = 10.433(1) Angstrom, b = 15.832(2) Angstrom, c = 19.292(3) Angstrom, V = 3186(1) Angstrom(3), and Z = 4. [Tp(But)]ZnNCS is monoclinic, P2(1)/n (NO. 14), a = 9.703(2) Angstrom b = 17.001(4) Angstrom, c = 16.582(3) Angstrom, beta = 95.08(1)degrees, V = 2725(1) Angstrom(3), and Z = 4. [Bp(But)]ZnBu(t) is monoclinic, P2(1)/n (No. 14), a = 14.912(7] Angstrom, b = 8.556(2) Angstrom, 18.482(5) Angstrom, beta = 112.86(3)degrees, V = 2173(2) Angstrom(3) and Z = 4. {[Bp(But)]Zn(mu-OH)}3 is orthorhombic, Pc2(1)n (No. 33), a = 12.302(2) Angstrom, b = 20.057(6) Angstrom, c = 22,110(2) Angstrom, V = 5455(2) Angstrom(3), and Z = 4.