Fluoro[eta(3)-hydrotris(3-R-5-methylpyrazol-1-yl)borato]zinc(II): The first TpZnF complexes, convenient precursors to zinc hydride complexes

Fluoro[eta(3)-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-Tol,Me)ZnOAc with KF in MeOH/THF and by reaction of KTp(t-Bu,Me) with Zn(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 = 11.8719(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 tetrafluoroborate 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)]+BF4- 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-Tol,Me)ZnX, whereas bis(trimethylsilyl)malonate yields the bridged complex Tp(p-Tol,Me)Zn-O-C(O)-CH2-C(O)-O-ZnTp(p-Tol,Me).