Synthesis and Crystal Structure of Unprecedented Oxo/Hydroxo-Bridged Polynuclear Gallium(III) Aqua Complexes

Two new polynuclear oxo/hydroxo-bridged polynuclear gallium(III) aqua complexes are obtained upon treatment of Ga3+(aq) with pyridine: the supramolecular compound of macrocyclic cavitand cucurbit[6]uril with gallium complex containing 32 metal atoms [Ga32(μ4-O)12(μ3-O)8(μ2-O)7(μ2-OH)39(H2O)20](PyH⊂C36H36N24O12)3(NO3)6·53H2O (1) and the tridecanuclear complex [Ga13(μ3-OH)6(μ2-OH)18(H2O)24](NO3)15·12H2O (2). It follows that two modes of nucleation exist when Ga3+(aq) is hydrolyzed: one around the tetrahedral GaO4 units (complex 1) and the other around the octahedral GaO6 units (complex 2). This is the first time that polynuclear oxo/hydroxo-bridged aqua complexes of Ga(III) have been isolated without the use of other ligands to control or block olygomerization.