Complexes of aluminium, gallium and indium trifluorides with neutral oxygen donor ligands: Synthesis, properties and reactions

Abstract The MF 3 ·3H 2 O (M = Al, Ga or In) dissolve in hot dimethylsulfoxide (dmso) to form [MF 3 (OH 2 ) 2 (dmso)]; further dmso is not incorporated even after prolonged reflux. The X-ray structure of [GaF 3 (OH 2 ) 2 (dmso)] shows mer fluorides and trans OH 2 ligands. The [GaF 3 (OH 2 ) 2 (dmso)] reacts with Me 3 tacn (1,4,7-trimethyl-1,4,7-triazacyclononane) or 2,2′-bipyridyl to give good yields of [GaF 3 (Me 3 tacn)]· x H 2 O and [GaF 3 (bipy)(OH 2 )]·2H 2 O at room temperature, previously obtained from GaF 3 ·3H 2 O by a hydrothermal route. [MF 3 (OH 2 ) 2 (dmso)] (M = Al or Ga) do not react with R 3 PO (R = Me or Ph) in CH 2 Cl 2 or MeOH, but with pyNO (pyridine-N-oxide), the products were [AlF 3 (OH 2 ) 2 (pyNO)] and [GaF 3 (OH 2 ) 2 (pyNO)]·pyNO·H 2 O. The structure of the latter shows equal numbers of the geometric isomers with mer – trans and mer – cis geometries, as well as lattice pyNO and H 2 O. Pentamethyldiethylenetriamine (PMDTA) and [GaF 3 (OH 2 ) 2 (dmso)] react to produce the zwitterion [GaF 4 (PMDTAH)]·2H 2 O, which contains κ 2 -PMDTA with the ‘free’ NMe 2 group protonated to balance the charge of the GaF 4 − unit. Crystals of [⊂Me 2 N(CH 2 ) 2 NMe(CH 2 ) 2 ] 2 [Ga 2 F 8 (OH 2 ) 2 ]·H 2 O containing a 1,1,4-trimethylpiperazinium cation, were obtained as a minor by-product. The anion is an edge-shared fluoride-bridged dimer, with the coordinated water ligands arranged anti . Attempts to prepare complexes with phosphine or thioether ligands by Cl/F exchange from the corresponding chloro-complexes with [NMe 4 ]F were unsuccessful, halide exchange being accompanied by liberation of the soft donor ligand. X-ray structures are also reported for [Me 2 NH 2 ][ trans -GaF 4 (OH 2 ) 2 ] and [AlCl 3 (OAsPh 3 )].