Fluoro[η3-hydrotris(3-R-5-methylpyrazol-1-yl)borato]zinc(II): The First TpZnF Complexes, Convenient Precursors to Zinc Hydride Complexes,

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Abstract
Fluoro[η3-tris(3-R-5-methylpyrazol-1-yl)hydroborato]zinc(II) complexes, TpR,MeZnF (with R = p-Tol, t-Bu), have been prepared by metathesis of Tpp-Tol,MeZnOAc with KF in MeOH/THF and by reaction of KTpt-Bu,Me with Zn(ClO4)2 and KF in MeOH. The molecular structure of Tpp-Tol,MeZnF has been determined by X-ray crystallography. Crystal data: a = 11.8719(12), c = 37.051(3) Å; trigonal, space group R3c (No. 161); Z = 6. The complex contains tetrahedrally coordinated Zn(II). The tolyl rings deviate by 21° from coplanarity with the pyrazolyl plane. The reaction of Tpp-Tol,MeZnF with py·BF3 leads to the tetrafluoroborate salt [Tpp-Tol,MeZn(py)]+BF4-. The analogous reaction with Et2O·BF3 probably gives a solvent complex [Tpp-Tol,MeZn(Et2O)]+BF4- that however could not be isolated. Triethylsilane reacts with Tpp-Tol,MeZnF to yield the zinc hydride Tpp-Tol,MeZnH. Trimethylsilyl derivatives Me3Si−X (X = Cl, Br, I, NCO, OAc) similarly give Tpp-Tol,MeZnX, whereas bis(trimethylsilyl) malonate yields the bridged complex Tpp-Tol,MeZn−O−C(O)−CH2−C(O)−O−ZnTpp-Tol,Me.