REACTIONS OF ALKALI-METAL POLY(1-PYRAZOLYL)BORATES WITH MAIN-GROUP-ELEMENT HALIDES

The pyrazabole analogues R2B(mu-pz)2M(C2H5)2 (Hpz = pyrazole; M = Al, R = C2H5; M = Ga, R = C2H5, C6H5, pz) have been prepared by the reaction of K[R2B(pz)2] with (C2H5)2MCl. K[B(pz)4] reacts with 1 molar equiv of MCl4 (M = Si, Ge, Sn) to form the complexes B[(pz)4]MCl3. Organosilicon as well as organogermanium poly(1-pyrazolyl)borates are unstable, but NMR data for autogeneously decomposing (at room temperature) [B(pz)4]2GeR2 (R = CH3, C2H5) could be obtained. Reaction of K[(C2H5)2B(pz)2] with R2MCl2 (M = Si, R = CH3; M = Ge, R = C2H5) proceeded by cleavage of a B-N bond of the ligand and pz- ion transfer from B to M to give (C2H5)2B(mu-pz)2B(C2H5)2 and R2M(pz)2. The complexes LSnCl3, LSnCl2(CH3), LSnCl(CH3)2, and LSnCl(C6H5)2 (L = [B(pz)4]) as well as L'SnCl(CH3)2 (L' = [(C6H5)2B(pz)2] or [(C2H5)2B(pz)2]) have been prepared. [(C6H5)2B(pz)2]SnCl(CH3)2 crystallizes in the triclinic system in space group P1BAR with a = 10.185 (4) angstrom, b = 10.613 (5) angstrom, c = 21.184 (9) angstrom, alpha = 77.54 (3)-degrees, beta = 76.66 (3)-degrees, gamma = 75.59 (3)-degrees, and Z = 4 at 293 K. [B(pz)4]SnCl(CH3)2 also crystallizes in the triclinic space group P1BAR with a = 8.881 (1) angstrom, b = 9.502 (1) angstrom, c = 12.198 (2) angstrom, alpha = 71.66 (1)-degrees, beta = 74.98 (1)-degrees, gamma = 80.45 (1)-degrees, and Z = 2 at 293 K. Phosphorus as well as sulfur chlorides interact with poly(1-pyrazolyl)borates by cleavage of one B-N bond of the ligand; pyrazaboles were obtained as the only boron-containing product. The same holds true for the reaction of (CH3)2AsBr with K[(C2H5)2B(pz)2], but the complex [B(pz)4]As(CH3)2 was obtained on reaction with K[B(pz)4].