Hydrothermal synthesis of Group 13 metal trifluoride complexes with neutral N-donor ligands

The reactions of the hydrated Group 13 fluorides, MF3·3H2O (M = Al, Ga or In) with 2,2':6',2''-terpyridyl, 2,2'-bipyridyl or 1,10-phenanthroline under hydrothermal conditions (180 °C/15 h) produced high yields of the complexes [MF3(terpy)]·3H2O, [MF3(bipy)(OH2)]·2H2O and [MF3(phen)(OH2)]. X-Ray crystal structures of [M'F3(terpy)]·3H2O (M' = Al or Ga), [M'F3(bipy)(OH2)]·2H2O and [GaF3(phen)(OH2)] show that all of them contain distorted octahedral geometries at the metal with mer-trifluoride coordination. Extensive H-bonding (FH-OH) links the molecules. The complexes have been further characterised by microanalysis, IR, (1)H, (19)F{(1)H} and (27)Al NMR spectroscopy. In contrast, reactions of the trifluorides with the acyclic triamine, N,N,N',N',N''-pentamethyldiethylenetriamine, under similar hydrothermal conditions results in cleavage of the triamine and ring-closure to form the 1,1,4-trimethylpiperazinium cation, [⊂Me2N(CH2)2NMe(CH2)2](+), with fluorometallate anions, and confirmed by X-ray analysis of [⊂Me2N(CH2)2NMe(CH2)2]2[Al2F8(OH2)2]·2H2O. The strongly H-bonded [GaF3(terpy)]·3H2O was also obtained by Cl/F exchange from [GaCl3(terpy)] and [NBu4]F or [K(2,2,2-crypt)]F. Crystallisation of a mixture of [NH4][PF6] and [GaF3(terpy)]·3H2O from aqueous solution produced the edge-bridged cationic complex, [{Ga(terpy)F}2(μ-F)2][PF6]2. The synthesis of the more sterically bulky [GaCl3((t)Bu3-terpy)] ((t)Bu3-terpy = 4,4'4''-tris-(t)Bu-2,2':6',2''-terpyridyl) and the crystal structure of [GaCl2((t)Bu3-terpy)][GaCl4], which contains a trigonal bipyramidal cation, are also reported.