Solvent influences on the molecular aggregation of magnesium aryloxides: synthesis, crystal structure, and solution characterization of Mg(OAr)(2)(L)(3) (OAr = DMP, DIP, TCP) and [Mg(DIP)(2)](3)

Magnesium aryloxides were prepared in a variety of solvents through the rea ction of dibutyl magnesium with sterically varied aryl alcohols: 2,6-dimeth ylphenol (H-DMP), 2,6-diisopropylphenol (H-DIP), and 2,4,6-trichlorophenol (H-TCP). Upon using a sufficiently strong Lewis-basic solvent, the solvated monomeric species Mg(DMP)(2)(py)(3) (1, py = pyridine), Mg(DIP)(2)(THF)(3) , (2a, THF = tetrahydrofuran) Mg(TCP)(2)(THF)(3) (3) were isolated. Each of these complexes possesses a five-coordinate magnesium that adopts a trigon al bipyramidal geometry. In the absence of a Lewis base, the reaction with H-DIP yields a soluble trinuclear complex, [Mg(DIP)(2)](3) (2b). The Mg met al centers in 2b adopt a linear arrangement with a four-coordinate central metal while the outer metal centers are reduced to just three-coordinate. S olution spectroscopic methods suggest that while 2b remains intact, the mon omeric species (1, 2a, and 3) are involved in equilibria which facilitate i ntermolecular ligand transfer. (C) 2000 Elsevier Science B.V. All rights re served.