Platinum complexes of vitamin C. NMR studies on the solution chemistry of cis-platinum(diamine)(ascorbate) complexes

Abstract

317ChemInform Abstract The variety of different products identified by using multinuclear NMR and HPLC techniques shows the complexity of the diamineplatinum(II) ascorbate system. Investigations are carried out on the reaction between sodium ascorbate and cis-(Pt(H2O)2(diamine))(NO3)2, where the diamine is two (15N)NH3, (1,2-15N2)en or 1,2-diaminocyclohexane (trans-R,R, trans-S,S or cis). The distribution of products isa function of amine ligands, reagent stoichiometry, pH, and time. Oxygen binding at O(2) and O(3) of the ascorbate anion is kinetically favoured, while carbon bonding at C(2) is thermodynamically favoured and accounts for essentially all of the products formed at long reaction time. In each of the diamine cases, a diastereofacial selectivity for substitution at the "re" face (re:si = 1.5-3.3) ofthe ascorbate anion is observed.

Structural and magnetic studies on mono- and polynuclear chromium ascorbate complexes

“…A group of complexes, prepared via reduction of several Cr VI species by ascorbate, has since been reported [7][8][9][10]. However, the structural information as yet available is still limited due to the problems commonly associated with the chemical instability of ascorbic acid, the low stability constants of the complexes [11] and their reluctance towards crystallization, excluding the few well characterized mixed ligand platinum ascorbate complexes [12][13][14][15][16].…”

Catalytic Oxidation of Ascorbic Acid on 2D and 3D Monolayers of 4‐Hydroxythiophenol

“…Spectroscopies [21,22], HPLC [22], and electrochemical methods [16, 19, 20, 23 -36] were often used for the determination of AA. Electrochemical oxidation of AA proceeds with high overpotentials using both metallic and carbon electrodes, and other compounds present in the solution may interfere in this determination.…”

Synthesis and Characterization of Platinum(II) Complexes ofl-Ascorbic Acid. Crystal Structure of Ascorbato-C2,O5-ethylenediamineplatinum(II) Dihydrate

“…Diamineplatinum complexes of vitamin C ( l -ascorbic acid) have received some attention because of their potential use as antitumor agents. − Apart from their biological activity, these complexes are also of interest from a chemical point of view. The C , O -bonded complex [Pt(Asc- C 2 , O 5 )( cis -dach)] (dach = 1,2-diaminocyclohexane) was the first transition metal complex of vitamin C to be structurally characterized by X-ray crystallography .…”