Jornal de Cromatografia e Técnicas de Separação
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Synthesis, Characterization of New Tungsten(IV)–Pterin Complexes and their Reactivity Studies towards Trimethylamine N-Oxide, Sodium Borohydride and Potassium Ferricyanide

Samir S, Siddhartha, Baisya S and Roy PS

2-Pivaloylamino-6-acetonyl-isoxanthopterin ((1), H2L) has been reacted with Na2WO4.2H2O under suitable conditions leading to the formation of Na2[W2IV(μ–O)(L)4(CH3OH)2] (2). Na[WIV(L)2(dedtc)]. CH3OH (3) and (Ph4P)2[WIV(L)2(aet)] (4) have been prepared by the reaction of (2) with PPh3 in presence of the ancillary ligands like sodium diethyldithiocarbamate trihydrate and 2-aminoethanethiol hydrochloride, respectively. These new compounds have been purified by flash chromatography and characterized by elemental analysis, different physicochemical and spectroscopic methods. Such data particularly 1H NMR and fluorescence spectra indicate the redox noninnocent nature of the pterin ligand. Reactivities of these compounds with different substrates have been followed kinetically; using the data of (3) as their representative, it appears that the electron transfer process (kobs=1.1x10-2s-1) involving K3[Fe(CN)6] is twice as fast as the group transfer processes associated with Me3N→O and NaBH4. The corresponding negative ΔS# values are consistent with associative pathways in all these cases.