title: Synthesis, characterization, and electronic structure of diimine complexes of chromium.
abstract: We have prepared and structurally characterized several complexes of chromium coordinated by diimine (or 1,4-diazadiene) ligands, that is, Ar-N=C(R)-(R)C=N-Ar (RL(Ar)) (where Ar = 2,6-diisopropylphenyl ("iPr") or 2,6-dimethylphenyl ("Me") and R = H or Me). The reaction of CrCl2 with HLiPr gave dinuclear [(HLiPr)Cr]2(mu-Cl)3(Cl)(THF) when isolated from Et2O; in THF solution, however, the product exists as mononuclear (HLiPr)CrCl2(THF)2. Two isostructural derivatives, (MeLMe)CrCl2(THF)2 and (HL(Me))CrCl2(THF)2, have also been prepared. Furthermore, the bis-ligand complex, (HLiPr)2Cr, has been prepared along with its reduction product, Li(THF)4[(HLiPr)2Cr]. We have also synthesized the tetracarbonyl complex, (HLiPr)Cr(CO)4, by addition of HLiPr to Cr(CO)4(NCCH3)2. The structure and variable temperature magnetic susceptibility of the previously reported Cr halide dimer, [(HLiPr)Cr(mu-Cl)]2, is also discussed in detail. All of the diimine complexes have been characterized structurally, spectroscopically, and magnetically, and their electronic structures are discussed with the aid of density-functional theory calculations.
authors.affiliation: Department of Chemistry and Biochemistry, Center for Catalytic Science and Technology, University of Delaware, Newark, Delaware 19716, USA.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Kreisel
authors.forename: Glenn P A
authors.initials: GP
authors.lastname: Yap
authors.forename: Klaus H
authors.initials: KH
authors.lastname: Theopold