Molybdenum complexes bearing the tris(1-pyrazolyl)methanesulfonate ligand: synthesis, characterization and electrochemical behaviour

• Autor(a) principal: Dinoi, Chiara
• Data de Publicação: 2010
• Outros Autores: Guedes Da Silva, M. Fátima C., Alegria, Elisabete, Smolenski, Piotr, Martins, Luisa, Poli, Rinaldo, Pombeiro, Armando
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.21/12061
• topic: Molybdenum; Scorpionates; Electrochemistry; Solid‐state structures

The tris(1‐pyrazolyl)methanesulfonate lithium salt Li(Tpms) [Tpms = SO3C(pz)3–] reacts with [Mo(CO)6] in NCMe heated at reflux to yield Li[Mo(Tpms)(CO)3] (1 ), which, upon crystallization from thf, forms the coordination polymer [Mo(Tpms)(CO)2(μ‐CO)Li(thf)2]n (2 ). Reaction of 1 with I2, HBF4 or AgBF4 yields [Mo(Tpms)I(CO)3] (3 ), [Mo(Tpms)H(CO)3] (5 ) or [Mo(Tpms)O2]2(μ‐O) (7 ), respectively. The high‐oxidation‐state dinuclear complexes [{Mo(Tpms)O(μ‐O)}2] (4 ) and [{Mo(tpms)OCl}2](μ‐O) (6 ) are formed upon exposure to air of solutions of 3 and 5 , respectively. Compounds 1 –7 , which appear to be the first tris(pyrazolyl)methanesulfonate complexes of molybdenum to be reported, were characterized by IR, 1H and 13C NMR spectroscopy, ESI‐MS, elemental analysis, cyclic voltammetry and, in the cases of Li(Tpms) and compounds 2 , 4· 2CH3CN, 6· 6CHCl3 and 7 , by X‐ray diffraction analyses. Li(Tpms) forms a 1D polymeric structure {i.e., [Li(tpms)]n } with Tpms as a tetradentate N2O2 chelating ligand that bridges two Li cations with distorted tetrahedral coordination. Compound 2 is a 1D coordination polymer in which Tpms acts as a bridging tetradentate N3O ligand and each Li(thf)2+ moiety is coordinated by one bridging CO ligand and by the sulfonyl group of a contiguous monomeric unit. In 4 , 6 and 7 , the Tpms ligand is a tridentate chelator either in the NNO (in 4 ) or in the NNN (in 6 and 7 ) fashion. Complexes 1 , 3 and 5 exhibit, by cyclic voltammetry, a single‐electron oxidation at oxidation potential values that indicate that the Tpms ligand has an electron‐donor character weaker than that of cyclopentadienyl.