Electronic Structure of Neutral and Monoanionic Tris(benzene-1,2-dithiolato)metal Complexes of Molybdenum and Tungsten

• Published in: Inorganic chemistry Vol. 46; no. 14; pp. 5642 - 5650
• Main Authors: Kapre, Ruta R, Bothe, Eberhard, Weyhermüller, Thomas, DeBeer George, Serena, Wieghardt, Karl
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09.07.2007
• Subjects: Anions - chemistry; Benzene - chemistry; Crystallography, X-Ray; ELECTRONIC STRUCTURE; Electrons; Ligands; MATERIALS SCIENCE; Models, Molecular; Molecular Structure; Molybdenum - chemistry; MOLYBDENUM COMPLEXES; ORGANOMETALLIC COMPOUNDS; Organometallic Compounds - chemistry; Other,OTHER; Oxidation-Reduction; Spectrum Analysis; Sulfhydryl Compounds - chemistry; Tungsten - chemistry; TUNGSTEN COMPLEXES
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic700600r

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 π-radical ligands (S rad = 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 π-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 S t = 0, which is generated by intramolecular, antiferromagnetic coupling between the MV (d1) central ion (S M = 1/2) and a ligand π radical (L• S,S)- (S rad = 1/2).