Preparation and characterisation of [M(CN)4O(pz)]2− complexes (M=Mo or W) and their reactivity towards molecular oxygen

Crystal structures of mixed-ligand oxocyano complexes of molybdenum(iv) and tungsten(iv) and their reactivity towards molecular oxygen studied by IR spectroscopy

“…UV-VIS reflectance spectra have been measured for the molybdenum (1-3) and tungsten (6)(7)(8)(9)(10)(11) salts. Each spectrum in the VIS/near UV part consists of a low-energy asymmetric band and a high-energy shoulder-like broad band.…”

“…3,4 In recent years the mixed-ligand tetracyanooxo complexes of molybdenum() and tungsten() of general formula [M(CN) 4 O(L)] nϪ , where L is a monodentate ligand such as CN Ϫ , CH 3 CN, pz (pyrazine), have been found useful in the activation of molecular oxygen. [5][6][7][8] In aerated polar organic solvents e.g. dichloromethane and acetonitrile they react with O 2 giving the same final product, (PPh 4 ) 2 [M(CN) 4 -O(O 2 )] (Ph = phenyl group).…”

[PPh4]3[W(CN)7(O2)]·4H2O as the Representative of the [M(L)7(LL)] Class for Nine-Coordinate Complexes

“…However, only a few of these compounds were obtained by the direct incorporation of atmospheric dioxygen; the majority were synthesized using H 2 O 2 as the source of the peroxo ligand. The precursor capable of binding O 2 (g) was either Mo IV metallooxoporphyrin [MO(por)] (where H 2 por = porphyrin or variously substituted porphyrin) or an oxocyanometalate(IV), [M IV (CN) 4 O(L)] 2-/3- (where M = Mo, W; L = pyrazine, pyridine, or cyanide). − The strong affinity of these precursors for dioxygen was revealed in the solid state and in organic solvents. The products of reactions with O 2 (g), [Mo VI O(O 2 )(por)] and [M VI (CN) 4 O(O 2 )] 2- , contain a peroxo ligand cis to the oxo in a distorted pentagonal bipyramidal structure. −, …”

“…Our strategy in this work was stimulated by recent reports on mixed-ligand cyanoperoxocomplexes of Mo and W. Such compounds are still scarce, and to our knowledge, in the group of cyanoperoxocomplexes of Mo(VI) and W(VI), there are only four known isolated species: [(CN) 5 Co III (μ-O 2 )Mo VI Cl(CN) 5 O] 6- dimer, [Mo(CN) 3 O(O 2 )(hmpa)] - (hmpa = hexamethylphosphoramide), [Mo(CN) 4 O(O 2 )] 2- , and [W(CN) 4 O(O 2 )] 2- . −, The latter two complexes were synthesized directly from tetracyano- or pentacyanooxocomplexes of M(IV) and molecular oxygen. − The aim of this work was to investigate the interactions between dioxygen and the intermediates derived from [M(CN) 8 ] 4- (M = Mo or W).…”

Tungsten-mediated synthesis of triazafluorenes

“…The complexes with half-unit Schiff bases containing pendant amine groups were particularly interesting for us since they could further be used as building blocks for extended systems. On the other hand, working with molybdenum and tungsten complexes, we have recently observed that several M(IV) cyano complexes participate in redox processes involving and influencing the reactivity of various ligands (O 2 , NO, nitriles, hydrazine) [9][10][11][12][13][14]. The propensity of these metals for both redox as well as template organic reactions prompted us to further study their reactivity towards potential Schiff-base components.…”