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, (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.

Group 3 metal trihalide complexes with neutral N-donor ligands – exploring their affinity towards fluoride

“…The These results explain why 'hydrated' Group 3 fluorides are not a viable entry into the coordination chemistry of these fluorides with neutral ligands. This contrasts sharply with the Group 13 fluoride hydrates, 19,29,30 and the Group 4 compounds, [MF 4 (OH 2 ) 2 ] (M = Zr, Hf ), 31 whose crystal structures show the water is coordinated to the metal, from which it can be displaced by neutral ligands. These are effective synthons for wider coordination chemistry.…”

“…1,15 Whilst the anhydrous Group 13 metal fluorides, MF 3 (M = Al, Ga, In) are similarly inert, the hydrates MF 3 •3H 2 O are more reactive; they can be reacted with neutral ligands to form metal trifluoride ligand complexes, [MF 3 (L)]•xH 2 O, most easily under hydrothermal conditions (180°C). 19,29,30 Therefore, we postulated that it may be possible to use the Group 3 metal fluoride hydrates [MF 3 •xH 2 O] (M = Sc, Y, La) to form analogous metal trifluoride ligand complexes. Literature data on the hydrates is sparse and the amount of water present apparently variable, although "x" typically appears to be less than one.…”

Exploring transition metal fluoride chelates – synthesis, properties and prospects towards potential PET probes

“…aqueous solution, room temperature or 80°C. 6,7,12 We also investigated the transition metal fluorides using Sc(III), Y(III), La(III) and Lu(III). 13 Among these d-and f-block metal systems, only the [ScF 3 (RMe 2 -tacn)] (R = Me, Bn) were successfully synthesised through Cl/F halide exchange reactions.…”

Trialkylstibine Complexes of Boron, Aluminum, Gallium, and Indium Trihalides: Synthesis, Properties, and Bonding

“…5,21−24 For the other systems (M = Al, Ga, In) the opposite order with X (Cl > Br > I) is generally found, 5,26 although it should be noted that packing effects, intermolecular interactions, hydrogen bonding, or interactions with solvate molecules can mask the expected trends in bond lengths within individual complexes. 27 The MF 3 species (M = Al, Ga, In) are inert polymers, and although some N-and O-donor ligand complexes have been prepared using [MF 3 (OH 2 ) 3 ] as synthons, 28,29 the latter do not react with soft donor ligands, and attempted Cl/F ligand exchange reactions on [MCl 3 L 3 ] typically result in loss of the soft donor ligand (L) and the trifluoride polymers are re-formed. 29 We recently reported the first X-ray structural data and detailed multinuclear spectroscopic data on seleno-and telluroether complexes of BX 3 30,31 and AlX 3 .…”

“…For boron, the Lewis acidity usually increases with X in the order F < Cl < Br < I; ,− recent computational effort has shown this to be due to the energies of the boron σ-bonding interactions, and hence the long-held view that B–X π-back-bonding is responsible has been discounted. ,− For the other systems (M = Al, Ga, In) the opposite order with X (Cl > Br > I) is generally found, , although it should be noted that packing effects, intermolecular interactions, hydrogen bonding, or interactions with solvate molecules can mask the expected trends in bond lengths within individual complexes . The MF 3 species (M = Al, Ga, In) are inert polymers, and although some N- and O-donor ligand complexes have been prepared using [MF 3 (OH 2 ) 3 ] as synthons, , the latter do not react with soft donor ligands, and attempted Cl/F ligand exchange reactions on [MCl 3 L 3 ] typically result in loss of the soft donor ligand (L) and the trifluoride polymers are re-formed …”