Arylalkane oxidation by dioxo[4,4′-di(tert-butyl)-2,2′-bipyridyl]molybdenum(VI) complexes

Abstract

Ary la I ka ne Oxid at io n by D ioxo[ 4,4/-d i ( tert-but y I ) -2,2'-bi pyr idyl] mol ybden u m ( VI) Complexes

Synthesis and Characterization of Halo, Cyanato, Thiocyanato and Selenocyanato Molybdenum(VI) Dioxo and Dioxo-μ-oxo Complexes

“…The torsion angles O2-Mo1...Mo2-O5 for (9) and O3-Mo1...Mo2-O5 for (7) are 114.6°and 165.0°, respectively. The lengths and angles are similar to other hexacoordinate dioxo Mo(VI), W(VI) and dioxo-l-oxo Mo(VI), W(VI) complexes containing bipyridine derivates and thiocyanato, halogen ligands [8,9,19,23]. …”

“…Whereas the l-oxo-bromo-dioxomolybdenum dimer was obtained by an analogous procedure from Na 2 MoO 4 in aqueous HBr and the adequate bipyridine, the monomeric dibromodioxomolybdenum complex was formed directly by reacting MoO 2 Br 2 with 2,2¢-t-butylpyridine in THF [19]. This method avoided the cumbersome involvment of the tetraphenylphosphonium salts.…”

Effect of an Ionic Liquid on the Catalytic Performance of Thiocyanatodioxomolybdenum(VI) Complexes for the Oxidation of Cyclooctene and Benzyl Alcohol

“…Arzoumanian and co-workers found that the tetraphenylphosphonium salt, (PPh 4 ) 2 [Mo VI O 2 (NCS) 4 ] (1), catalysed the model reaction approximately 20 times more efficiently than Mo VI O 2 (S 2 CNEt) 2 [9]. In an attempt to improve the oxidising power of the anion [Mo VI O 2 (NCS) 4 ] 2-, the same group reacted 1 with various bipyridines and obtained, in the case of 4,4 0 -di-tert-butyl-2,2 0 -bipyridine, the neutral monomer Mo VI O 2 (NCS) 2 (di-tBu-bipy) (2) [10,11] with exceptional OAT properties, not only towards phosphines, but also towards arylalkanes and alcohols [12,13]. These oxidation reactions become catalytic in the presence of DMSO.…”

95Mo NMR: a useful tool for structural studies in solution

“…1). The solid-state structures of the monometallic (I-VI) [9,13,14] and bimetallic (IX-XI) [11,16] complexes show a distorted octahedral geometry around the metal atom, while for the heptacoordinated compounds VII and VIII, the ligands are placed around the molybdenum centre giving a pseudopentagonal bipyramidal geometry. [8,15] The chemical shifts observed cover a wide range (ca 1100 ppm, from +500 to −600 ppm), depending on the electronic density on the metal by modulation of the coordinated ligands (Table 1 and Fig.…”

“…An exponential window function was applied with a line broadening of 20-200 Hz before Fourier transform to obtain an optimum signal-to-noise ratio. Ligands 3, [12] (R)-4 and (S)-5, [9] and complexes II, [13] III and XI, [11] IV-V, [9] VI, [14] VII, [15] IX [16] and X [8] were prepared according to published methods. Complexes I [17] and VIII [18] were prepared following the methodology described for related compounds.…”