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

Abstract

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, 1H, 19F{1H} and 27Al 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(?-F)2][PF6]2. The synthesis of the more sterically bulky [GaCl3(tBu3-terpy)] (tBu3-terpy = 4,4?4??-tris-tBu-2,2?:6?,2??-terpyridyl) and the crystal structure of [GaCl2(tBu3-terpy)][GaCl4], which contains a trigonal bipyramidal cation, are also reported.

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Identifiers

ORCID for William Levason: orcid.org/0000-0003-3540-0971

ORCID for Francesco M. Monzittu: orcid.org/0000-0002-7080-3795

ORCID for Gillian Reid: orcid.org/0000-0001-5349-3468

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