title: Electronic structure of neutral and monoanionic tris(benzene-1,2-dithiolato)metal complexes of molybdenum and tungsten.
abstract: The reaction of 3 equiv of the ligand 2-mercapto-3,5-di-tert-butylaniline, H2[LN,S], or 3,5-di-tert-butyl-1,2-benzenedithiol, H2[LS,S], with 1 equiv of [MoO2(acac)2] or WCl6 (acac=acetonylacetate(1-)) in methanol or CCl4 afforded the diamagnetic neutral complexes [MoV(LN,S)2(L*N,S)]0 (1), [MoV(LS,S)2(L*S,S)] (2), and [WV(LS,S)2(L*S,S)] (3), where (L*N,S)- and (L*S,S)- represent monoanionic pi-radical ligands (Srad=1/2), which are the one-electron oxidized forms of the corresponding closed-shell dianions (LN,S)2- and (LS,S)2-. Complexes 1-3 are trigonal-prismatic members of the electron-transfer series [ML3]z (z=0, 1-, 2-). Reaction of 2 and 3 with [N(n-Bu)4](SH) in CH2Cl2 under anaerobic conditions afforded paramagnetic crystalline [N(n-Bu)4][MoV(LS,S)3] (4) and [N(n-Bu)4][WV(LS,S)3] (5). Complexes 1-5 have been characterized by X-ray crystallography. S K-edge X-ray absorption and infrared spectroscopy prove that a pi-radical ligand (L*S,S)- is present in neutral 2 and 3, whereas the monoanions [MV(LS,S)3]- contain only closed-shell dianionic ligands. These neutral species have previously been incorrectly described as [MVI(L)3]0 complexes with a MoVI or WVI (d0) central metal ion; they are, in fact MV (d1) (M=Mo, W) species: [MoV(LS,S)2(L*S,S)] and [WV(LS,S)2(L*S,S)] with a diamagnetic ground state St=0, which is generated by intramolecular, antiferromagnetic coupling between the MV (d1) central ion (SM=1/2) and a ligand pi radical (L*S,S)- (Srad=1/2).
authors.affiliation: Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Ruta R
authors.initials: RR
authors.lastname: Kapre
authors.forename: Eberhard
authors.initials: E
authors.lastname: Bothe
authors.forename: Thomas
authors.initials: T
authors.lastname: Weyhermüller
authors.forename: Serena
authors.initials: S
authors.lastname: DeBeer George
authors.forename: Karl
authors.initials: K
authors.lastname: Wieghardt
mesh_terms: D000838:Anions / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004583:Electrons; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D013057:Spectrum Analysis; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014414:Tungsten / Q000737:chemistry*
chemical_list: D000838:Anions; D008024:Ligands; D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; D008982:Molybdenum; D001554:Benzene; D014414:Tungsten