HYDROTRIS(3-R-5-METHYLPYRAZOL-1-YL)BORATO]ZINC(II) - THE FIRST TPZNF COMPLEXES, CONVENIENT PRECURSORS TO ZINC HYDRIDE COMPLEXES

tris(3-R-5-methylpyrazol-1-yl)hydroborato]zinc(II) complexes, Tp(R,Me) ZnF (with R = p-Tol, t-Bu), have been prepared by metathesis of Tp(p-T ol,Me)ZnOAc with KF in MeOH/THF and by reaction of KTp(t-Bu,Me) with Z n(ClO4)(2) and KF in MeOH. The molecular structure of Tp(p-Tol,Me)ZnF has been determined by X-ray crystallography. Crystal data: a = 11.871 9(12), c = 37.051(3) Angstrom; trigonal, space group R3c (No. 161); Z = 6. The complex contains tetrahedrally coordinated Zn(II). The tolyl rings deviate by 21 degrees from coplanarity with the pyrazolyl plane. The reaction of Tp(p-Tol,Me)ZnF with py . BF3 leads to the tetrafluor oborate salt [Tp(p-tol,Me)Zn(py)]+BF4-. The analogous reaction with Et (2)O . BF3 probably gives a solvent complex [Tp(p-Tol,Me)Zn(Et(2)O)]+B F4- that however could not be isolated. Triethylsilane reacts with Tp( p-Tol,Me)ZnF to yield the zinc hydride Tp(p-Tol,Me)ZnH. Trimethylsilyl derivatives Me(3)Si-X (X = Cl, Br, I, NCO, OAc) similarly give Tp(p-T ol,Me)ZnX, whereas bis(trimethylsilyl)malonate yields the bridged comp lex Tp(p-Tol,Me)Zn-O-C(O)-CH2-C(O)-O-ZnTp(p-Tol,Me).