title: The effect of substituents on the phenyl portion of the imido ligand on the structure and properties of molybdenum(VI) imido complexes.
abstract: Anilines with alkyl substituents on the phenyl ring (ArNH2 = 2,4,6-trimethylaniline; 2,3-, 2,4-, 2,6-, and 3,4-dimethylaniline; and 2,6-diisopropylaniline) react with MoO(X)2(dtc)2 (X = Cl or Br; dtc = diethyldithiocarbamate) in methanol in the presence of 2 equiv of triethylamine to form ionic imido complexes of the type [MoNAr(dtc)3]2[Mo6O19] or MoNAr(dtc)3]4[Mo8O26]. The same reaction in THF with butyllithium as base yields imido complexes of the type MoNAr(X)2(dtc)2. The structures of three ionic, five chloro, and two bromo complexes have been determined by X-ray crystallography. In all complexes, the molybenum center is a distorted pentagonal bipyramid. While the structures are similar, the angles of the imido linkages differ. The effect of the substituents on the phenyl ring of the imido ligand on the 95Mo NMR chemical shifts was determined. The Mo nucleus becomes more deshielded with the substituents in the following order: 3,4-Me2 < 2,3-Me2 < 2,4-Me2 < 2,6-Me2 < 2,4,6-Me3 < 2,6 isopropyl. Complexes with more deshielded 95Mo centers tend to have angles of the imido linkage that are closer to 180 degrees.
authors.affiliation: Department of Chemistry, Grinnell College, Grinnell, Iowa 50112, USA. minelli@grinnell.edu
authors.forename: Martin
authors.initials: M
authors.lastname: Minelli
authors.forename: My Le
authors.initials: ML
authors.lastname: Hoang
authors.forename: Michael
authors.initials: M
authors.lastname: Kraus
authors.forename: Gena
authors.initials: G
authors.lastname: Kucera
authors.forename: Jennifer
authors.initials: J
authors.lastname: Loertscher
authors.forename: Mark
authors.initials: M
authors.lastname: Reynolds
authors.forename: Nathan
authors.initials: N
authors.lastname: Timm
authors.forename: Michael Y
authors.initials: MY
authors.lastname: Chiang
authors.forename: Douglas
authors.initials: D
authors.lastname: Powell