The direct electrochemical synthesis of some metal derivatives of 3-hydroxy-2-methyl-4-pyrone

Abstract

. Can. J. Chem. 68, 1598 (1990).The electrochemical oxidation of a metallic sacrificial anode (M = Zn, Cd, Sn, In, Cu) in a non-aqueous solution of 3-hydroxy-2-methyl-4-pyrone (= HL) yields the ML, complexes (M = Zn, Cd, Sn, Cu, n = 2; M = In, n = 3). Adducts of the type ML2.B (M = Zn, Cd, B = N,N,N1,N'-tetramethylethylenediamine (tmen); M = Cu, B = triphenylphosphine) were obtained by the reaction between the appropriate ligand (B) and the previously synthesized complexes (M = Zn, Cd), or by arranging for the initial electrolytic phase to include the base (M = Cu). The tin(I1) compound shows the typical reactions of such low oxidation state species by reacting with iodine and ortho-quinones by oxidative addition. All compounds were characterized by elemental analysis and by IR, 'H and I3C n1111. spectroscopy. The structure of CdL2.tmen was determined by X-ray crystallography, which identified the Cd04N2 kernel, and partial electron delocalization within the pyronate ring. Key words: electrochemical synthesis, cadmium complexes, zinc complexes, tin(I1) oxidation, 3-hydroxy-2-methy 1-4-pyrone. Mots cle's: synthkse tlectrochimique, complexes du cadmium, complexes du zinc, oxydation du Zn(II), 3-hydroxy-2-mtthyl-4-pyrone.[Traduit par la revue]

A Simple Model for the Enzyme-Substrate-Complex of the Quercetinase Reaction. Crystal Structure of Flavonolatocobalt(III)(salen)

“…The 'H N M R spectrum o f 1 shows a multiplet around ö 3 .6-4.2, assigned to the ethylene group, suggest ing a twisted conform ation of the salen ligand [6], but no final evidence has been obtained so far. Re cently, X-ray crystal analyses of flavonolates have been reported o f Cu(I) (tetrahedral geometry) [7] as well as Cu(II) (planar) [8], and Z n(Il) (octa hedral) [9], However, the structure of a flavonolate complex of Co(III) and a tretradentate ligand (as salen) with high selectivity of its catalytic activity is still missing.…”

The use of sacrificial anodes for the electrochemical synthesis of metallic complexes

“…proposed: a disproportionation reaction to give Cu(0) and a Cu(II) complex [40], also in acetonitrile and under a dry nitrogen atmosphere, according to the mechanism, reported in eq. 9, A c c e p t e d M a n u s c r i p t The direct electrochemical oxidation to Cu(II) was also reported.…”

“…Another possible alternative mechanism was also proposed [40,48]; it is based on a disproportonation process to give In(0) and the In(III) complex, also in acetonitrile and under a dry nitrogen atmosphere, according to:…”

“…This is an unstable species and suffers further an oxidation [44][45][46][47] or disproportionation [40,48] process in solution to give the In(III) complex.…”

N,N′-Dialkyldithiocarbamate chelates of indium(III): alternative synthetic routes and thermodynamics characterization

“…The method of preparation of these compounds was essentially the same as that used in our previous publications [6,7]. The solution phase (ca.…”