Diorganogallium β-Diketonates and Their Lewis Acid−Base Adducts. Crystal and Molecular Structures of Mes<INF>2</INF>Ga(hfac) and Me<INF>2</INF>Ga(hfac)·NC<INF>5</INF>H<INF>5</INF>

Compounds of the type R<INF>2</INF>Ga(bdk) (R = Me, Et, Mes (mesityl); bdk = 2,4-pentanedionato (acac), 1,1,1-trifluoro-2,4-pentanedionato (tfac), 1,1,1,5,5,5-hexafluoro-2,4-penatedionato (hfac), 2,2,6,6-tetramethyl-3,5-heptanedionato (tmhd)) have been prepared by multiple routes, including hydrocarbon elimination, metathesis, and ligand redistribution reactions, and fully characterized by elemental analyses, cryoscopic molecular weight studies in benzene, and IR and multinuclear NMR spectroscopic studies. An X-ray structural study of Mes<INF>2</INF>Ga(hfac) demonstrated four-coordinate gallium with σ bonds to the two mesityl rings and to the two oxygen atoms of the β-diketonate ligand. The Lewis acidities of the diorganogallium β-diketonate derivatives toward NMe<INF>3</INF> and/or pyridine were also investigated. Two adducts, Me<INF>2</INF>Ga(hfac)·NMe and Me<INF>2</INF>Ga(hfac)·py, were stable to dissociation at room temperature and thus were fully characterized by elemental analysis, cryoscopic molecular weight studies in benzene, vapor pressure−temperature studies, and IR and multinuclear NMR (including variable temperature) spectroscopic studies. The compound Me<INF>2</INF>Ga(hfac)·py was also characterized by an X-ray structural study. The structure involved five-coordinate gallium with one Ga−N, two (inequivalent) Ga−O, and two Ga−C bonds.