GALLIUM COMPLEXES OF POTENTIALLY TRIDENTATE POLY(PYRAZOLYL)BORATE LIGANDS - CRYSTAL AND MOLECULAR-STRUCTURES OF [HB(3,5-ME2PZ)3]GA(CH3)CL, [HB(3,5-ME2PZ)3]GA(CH3)2, AND [B(PZ)4]2GACH3 (PZ = PYRAZOLYL RING)

The potentially tridentate ligands [HB(PZ)3]- and [B(PZ)4]- react with GaCl3 to yield the respective salts [(ligand)2Ga]GaCl4. These compounds are stable and do not react with nucleophiles. The six coordinate cations are also formed in the reactions of 1 equiv of [HB(pz)3]-or [B(PZ)4]- with GaCH3Cl2. The reaction of [HB(3,5-Me2PZ)3]- with GaCH3CI2 yields [HB(3,5-Me2PZ)3]Ga(CH3)Cl. The solid state structure of this complex shows that it is four coordinate with a bidentate hydrotris(pyrazolyl)borate ligand. This complex is fluxional in solution, showing equivalent pyrazolyl rings in the H-1 NMR spectra even at -90-degrees-C. The reaction of [HB(PZ)3]-, [B(PZ)4]-, or [HB(3,5-Me2PZ)3]- with Ga(CH3)2Cl yields the respective (ligand)Ga(CH3)2 complexes. The solid state structure of [HB(3,5-Me2pz)3]Ga(CH3)2 shows that it is also four coordinate. Both [HB(3,5-Me2PZ)3]Ga(CH3)2 and [HB(pz)3]Ga(CH3)2 are fluxional in solution, showing equivalent pyrazolyl rings and methyl ligands at ambient temperature. At low temperatures a 2/1 pattern for each resonance type in the pyrazolyl rings and a 1/1 ratio for the methyl groups is observed. The reaction of 2 equiv of [HB(pz)3]- or [B(PZ)4]- with GaCH3Cl2 yields the respective (ligand)2GaCH3 complexes. The solid state structure of [B(PZ)4]2-GaCH3 shows that it is six coordinate containing both a tridentate and bidentate tetrakis(pyrazolyl)borate ligand. The low temperature H-1 NMR spectrum of [HB(PZ)3]2GaCH3 shows a 1/1/2/2 pattern for each pyrazolyl ring resonance type, indicating a similar structure for [HB-(PZ)3]2GaCH3. Crystal data: [HB(3,5-Me2PZ)3]Ga(CH3)Cl, monoclinic, P2(1)/c, a = 13.705(7) angstrom, b = 7.780(3) angstrom, c = 18.684(8) angstrom, beta = 93.71(4)-degrees, V = 1988 angstrom3, Z = 4, R(F) = 6.1%; [HB(3,5-Me2pz)3]Ga(CH3)2, triclinic, P1BAR a = 7.976(3) angstrom, b = 18.520(11) angstrom, c = 7.942(3) angstrom, alpha = 97.01(4)-degrees, beta = 116.28(3)-degrees, gamma = 93.54(4)-degrees, V = 1035 angstrom3, Z = 2, R(F) = 6.8%; [B(pz)4]2GaCH3, triclinic, P1BAR, a = 12.316(6) angstrom, b = 15.945(4) angstrom, c = 8.622(4) angstrom, alpha = 101.51(4)-degrees, beta = 99.66(4)-degrees, gamma = 93.83(4)-degrees, V = 1627 angstrom3, Z = 2, R(F) = 5.9%.