title: Radical anionic versus neutral 2,2'-bipyridyl coordination in uranium complexes supported by amide and ketimide ligands.
abstract: The synthesis and characterization of (bipy)(2)U(N[t-Bu]Ar)(2) (1-(bipy)(2), bipy = 2,2'-bipyridyl, Ar = 3,5-C(6)H(3)Me(2)), (bipy)U(N[(1)Ad]Ar)(3) (2-bipy), (bipy)(2)U(NC[t-Bu]Mes)(3) (3-(bipy)(2), Mes = 2,4,6-C(6)H(2)Me(3)), and IU(bipy)(NC[t-Bu]Mes)(3) (3-I-bipy) are reported. X-ray crystallography studies indicate that bipy coordinates as a radical anion in 1-(bipy)(2) and 2-bipy, and as a neutral ligand in 3-I-bipy. In 3-(bipy)(2), one of the bipy ligands is best viewed as a radical anion, the other as a neutral ligand. The electronic structure assignments are supported by NMR spectroscopy studies of exchange experiments with 4,4'-dimethyl-2,2'-bipyridyl and also by optical spectroscopy. In all complexes, uranium was assigned a +4 formal oxidation state.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA. pld@chem.ucla.edu ccummins@mit.edu.
authors.forename: Paula L
authors.initials: PL
authors.lastname: Diaconescu
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Cummins
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry*; D000577:Amides / Q000737:chemistry*; D000838:Anions / Q000737:chemistry; D018360:Crystallography, X-Ray; D007097:Imines / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D014501:Uranium / Q000737:chemistry*
chemical_list: D000577:Amides; D000838:Anions; D007097:Imines; D008024:Ligands; D009942:Organometallic Compounds; D014501:Uranium; D015082:2,2'-Dipyridyl