The Chemistry of Quinones. II. Synthesis of Polysubstituted Naphthoquinones

Abstract

Solutions of copper(II) salts and excess 2,9-dimethyl-1,10-phenanthroline (dmp) in organic solvents yielded complexes of formula Cu(dmp),X,.H,O, where X=NO3, Cl, and Br. When excess of the copper(II) salt was present, mono complexes represented by CudmpX2, where X=NO3, Cl, Br ; 2X=SO4 were obtained. Copper(II) perchlorate-dmp mixtures yielded hydrated Cu(dmp),(ClO4)2. Aqueous solutions of the bis complexes changed colour when boiled and deposited red crystals of composition Cu(dmp)2X, with water of crystallization in some cases. Bis(dmp)copper(I) nitrate, perchlorate, and sulphate were also produced by reduction of the copper(II) complexes with hypophosphorus acid or hydroxylamine salts. The visible absorption curves for solutions of the complexes Cu(dmp)2X, corresponded with those reported in studies of the spectrophotometric estimation of copper using dmp. Mono complexes of formula CudmpX, where X=Cl, Br, and I, were prepared by reduction of the corresponding copper(II) complexes.

The structure of sitting-atop complexes of metalloporphyrins studied by theoretical methods

“…In order to check the performance of the current method on some relevant complexes, we optimised the structure of CuPor, CuAn 2þ 6 and CuAn þ 4 and compared it to EXAFS and X-ray data. For CuPor, the optimised Cu-N bonds (202 pm) are identical to those measured by EXAFS [23], but 1-4 pm longer than distances obtained by X-ray crystallography on various porphyrins [55][56][57][58]. For CuAn 2þ 6 , the optimised Cu-N distances (4 Â 200, 238, and 239 pm) are 1 pm longer (equatorial) or 1-2 pm shorter (axial) than those obtained by EXAFS methods [23].…”

Rates of electron-transfer reactions of some copper(II)-phenanthroline complexes with cytochrome c(II) and tris(phenanthroline)cobalt(II) ion

“…12 In early work Cu(dmphen)22+ solutions were prepared by dissolving the required amount of the solid complex prepared according to the method of Hall, Marchant, and Plowman. 13 No significant difference in behavior was found between these solutions and solutions prepared from the metal and ligand separately. Where dissociation of the complexes was significant, the concentrations of the reactant species were calculated from the published stability constant and pifa values.2 All reactant solutions were maintained at a pH of 6.15 with 2 M MES (2-(A-morpholino)ethanesulfonic acid) buffer14 and at an ionic strength of 0.1 M with sodium nitrate, unless otherwise specified.…”

An unexpected G-G base pairing caused by the coordination of platinum(II) at the N(7) position of 9-ethylguanine

“…The interaction between the two cations is represented schematically in Figure 2. Hydrogen-bond distances are 0(6a)-N(2a)', 2.99 (2) A; N(la)-N(la)', 2.77 (2) A. Thus, the coordination of Pt(II) at the N(7) position has shifted the pK of the N(l) position sufficiently to produce significant amounts of both protonated and deprotonated guanine at pH 7 and allow the G-G base pairing (Figure 2b), which is quite unlike that observed in poly(G) and poly(dG) helices,33"35 guanosine and guanine gels,36 or the Donohue (26) Gellert, R. W.; Bau, R. J.…”