ORGANOMETALLIC COMPLEXES OF GALLIUM STABILIZED BY THE DIHYDROBIS(PYRAZOLYL)BORATE LIGAND

The reaction of GaCl3with 2 and 3 equiv of K[H2B(pz)2] (pz = pyrazolyl ring) yields [H2B(pz)2]2GaCl (1) and [H2B(pz)2]3Ga (2), respectively, but the reaction with 1 equiv of the ligand salt yields {[H2B- (pz)2]2Ga}GaCl4(3). The complexes [H2B(pz)2]2GaCH3(4) and [H2B(pz)2]Ga(CH3)Cl (5) are prepared from the reaction of CH3GaCl2with 2 or 1 equiv of K[H2B(pz)2], respectively. Complex 5 also forms in the exchange reaction of (CH3)2GaCl and [H2B(pz)2]2GaCl. [H2B(pz)2]Ga(CH3)2(6) is prepared by the reaction of (CH3)2GaCl and K[H2B(pz)2]. It is also formed in the reaction of 5 with CH3Li. The reaction of 3 with 1 equiv of CH3Li yields a mixture of 4 and 6. The reaction of 3 with 4 equiv of CH3Li yields 6 exclusively and in high yield based on both gallium atoms in 3. The dimethyl complex 6 reacts with CH3C02H to yield [H2B(pz)2](CH3)Ga(O2CCH3) (7). The monomethyl complexes 4 and 7 are stable in the presence of CH3CO2H. The organometallic complexes 4-7 are all monomeric in benzene solution and stable to air for extended periods. CH3CO2H reacts with [H2B(pz)2]3Ga to yield [H2B(pz)2]2Ga(O2CCH3) (8). Molecular weight determinations for 8 in benzene solution yield values between a monomer and a dimer. An X-ray crystallographic study shows that in the solid state 8 is monomeric with an octahedral geometry about gallium. Crystal data: monoclinic, P21/n, a = 8.492 (2) Å, b = 8.087 (6) Å, c = 8.278 (2) Å, ß = 103.85 (2) °, V = 1917 Å3, Z = 4, and ρ = 1.465 g cm-3. © 1990, American Chemical Society. All rights reserved.