title: Synthesis, Structure, and Properties of Al((R)bpy)3 Complexes (R = t-Bu, Me): Homoleptic Main-Group Tris-bipyridyl Compounds.
abstract: The neutral homoleptic tris-bpy aluminum complexes Al((R)bpy)3, where R = tBu (1) or Me (2), have been synthesized from reactions between AlX precursors (X = Cl, Br) and neutral (R)bpy ligands through an aluminum disproportion process. The crystalline compounds have been characterized by single-crystal X-ray diffraction, electrochemical experiments, EPR, magnetic susceptibility, and density functional theory (DFT) studies. The collective data show that 1 and 2 contain Al(3+) metal centers coordinated by three bipyridine (bpy(•))(1-) monoanion radicals. Electrochemical studies show that six redox states are accessible from the neutral complexes, three oxidative and three reductive, that involve oxidation or reduction of the coordinated bpy ligands to give neutral (R)bpy or (R)bpy(2-) dianions, respectively. Magnetic susceptibility measurements (4-300 K) coupled with DFT studies show strong antiferromagnetic coupling of the three unpaired electrons located on the (R)bpy ligands to give S = (1)/2 ground states with low lying S = (3)/2 excited states that are populated above 110 K (1) and 80 K (2) in the solid-state. Complex 2 shows weak 3D magnetic interactions at 19 K, which is not observed in 1 or the related [Al(bpy)3] complex.
authors.affiliation: Department of Chemistry and Biochemistry University of Maryland-College Park , College Park, Maryland 20742, United States.
authors.forename: Samantha
authors.initials: S
authors.lastname: DeCarlo
authors.affiliation: Department of Chemistry and Biochemistry University of Maryland-College Park , College Park, Maryland 20742, United States.|Research Department Naval Surface Warfare Center Indian Head EOD Tech Division, Indian Head, Maryland 20640, United States.
authors.forename: Dennis H
authors.initials: DH
authors.lastname: Mayo
authors.affiliation: Department of Physics, Naval Postgraduate School , Monterey, California 93943, United States.
authors.forename: Warren
authors.initials: W
authors.lastname: Tomlinson
authors.affiliation: Department of Chemistry and Biochemistry University of Maryland-College Park , College Park, Maryland 20742, United States.
authors.forename: Junkai
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Physics, Naval Postgraduate School , Monterey, California 93943, United States.
authors.forename: Joseph
authors.initials: J
authors.lastname: Hooper
authors.affiliation: Department of Chemistry and Biochemistry University of Maryland-College Park , College Park, Maryland 20742, United States.
authors.forename: Peter
authors.initials: P
authors.lastname: Zavalij
authors.affiliation: Departments of Chemistry and Materials Science Johns Hopkins University , Baltimore, Maryland 21218, United States.
authors.forename: Kit
authors.initials: K
authors.lastname: Bowen
authors.affiliation: Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT) , D-76128 Karlsruhe, Germany.
authors.forename: Hansgeorg
authors.initials: H
authors.lastname: Schnöckel
authors.affiliation: Department of Chemistry and Biochemistry University of Maryland-College Park , College Park, Maryland 20742, United States.
authors.forename: Bryan
authors.initials: B
authors.lastname: Eichhorn