Reactions Of K2 Research Articles

Synthesis, spectral characterization and antibacterial studies of palladium(II) complexes of heterocyclic thiones

Reactions of K2[PdCl4] with heterocyclic thiones in molar ratios of 1:2 and 1:4 in water-methanol medium yielded the palladium(II) complexes with the general formula of either [Pd(L)Cl2], [Pd(L)2]Cl2or [Pd(L)4]Cl2where L ═ Imidazolidine-2-thione (Imt), 2-Mercaptopyridine (Mpy), 2-Mercaptopyrimidine (Mpm), 6-Mercaptopurine (6-Mp) and Thionicotinamide (Tna). The complexes were characterized by elemental analysis and spectroscopic (IR,1H and13C NMR) methods. An upfield shift in the >C═S resonance of thiones in13C NMR and downfield shift in N–H or aromatic proton resonances in1H NMR are consistent with the sulfur coordination to palladium(II). The complexes were screened for antibacterial activity, and the results showed that the complexes exhibited moderate activities as compared to that of a standard drug.

Synthesis, spectral characterization and antibacterial studies of palladium(II) complexes of heterocyclic thiones

Reactions of K2[PdCl4] with heterocyclic thiones in molar ratios of 1:2 and 1:4 in water-methanol medium yielded the palladium(II) complexes with the general formula of either [Pd(L)Cl2], [Pd(L)2]Cl2 or [Pd(L)4]Cl2 where L ═ Imidazolidine-2-thione (Imt), 2-Mercaptopyridine (Mpy), 2-Mercaptopyrimidine (Mpm), 6-Mercaptopurine (6-Mp) and Thionicotinamide (Tna). The complexes were characterized by elemental analysis and spectroscopic (IR, 1H and 13C NMR) methods. An upfield shift in the >C═S resonance of thiones in 13C NMR and downfield shift in N–H or aromatic proton resonances in 1H NMR are consistent with the sulfur coordination to palladium(II). The complexes were screened for antibacterial activity, and the results showed that the complexes exhibited moderate activities as compared to that of a standard drug.

Reactions of Nitroplatinum Complexes. 2. Reactions of K2[Pt(NO2)4] and Related Complexes with Aqueous Acids (CH3CO2H, HClO4, CF3SO3H, HNO3, and H2SO4): Pathways to Platinum(III) Complexes with Acetate Bridges. Crystal Structure of K2[{Pt(NO2)2(.mu.-CH3CO2)}2].cntdot.H2O

Full title: Reactions of nitroplatinum complexes. 2. Reactions of K2[Pt(NO2)4] and related complexes with aqueous acids (CH3CO2H, HClO4, CF3SO3H, HNO3, and H2SO4): Pathways to platinum(III) complexes with acetate bridges. Crystal structure of K2[{Pt(NO2)22(μ-CH 3CO2)}2]·H2O. Reaction of K2[Pt(15NO2)4] under argon with 1 M HClO4 or CF3SO3H gave an initial blue solution (λmax = 627 nm), due to nitrosyl complexes of platinum(IV). With heating, the color faded, and 195Pt and 15N NMR peaks were observed from cis-[Pt(15NO2)2(H2O)2], [Pt(15NO2)(H2O)3]+, and fac-[Pt(15NO2)3(H2O) 3]+. In air or oxygen, reaction was faster, giving [Pt(H2O)4]2+ as well as mixed nitrito-N/aqua platinum(II) complexes, and larger proportions of platinum(IV) complexes, including [Pt(OH)6]2- in solution, and solid H2[Pt(OH)6]. With 0.5 M H2SO4, reactions were similar, but a greater variety of platinum(IV) complexes were formed, some probably containing coordinated sulfate. With 1 M HNO3, K2[Pt(NO2)6] formed. Reactions of K2[Pt(NO2]4] with aqueous acetic acid gave mixtures of Pt(II) and Pt(IV) mononuclear complexes and dinuclear Pt(III) complexes containing acetate bridges. The composition of the solution depended on the reaction conditions (heated for various times with argon, air, or oxygen above the solution or bubbled through). Crystals of K2[{PtII(NO2)2(μ-CH 3CO2)}2]·H2O were obtained from a reaction under argon, and the crystal structure was determined by X-ray diffraction: space group P1 (no. 2); a = 7.202(2) A; b = 8.987(2) A; c = 13.592(2) A; α = 94.01(2)°; β = 90.68(2)°; γ = 111.04(2)°; Z = 2; R = 0.0371, for 2875 reflections. The structure showed two acetate ligands bridging between cis-Pt(NO2)2 units, with the Pt-Pt distance 2.986(1) A. Reactions of cis-[Pt(NO2)2(H2O)2] with various oxidants in the presence of acetic acid were studied. [{(CH3CO2)PtIII(NO2) 2(μ-CH3CO2)}2]2- is formed by the oxidation of preformed [{PtII(NO2)2(μ-CH3CO 2)}2]2-. Under anaerobic conditions, the major oxidant is HNO3 formed in the reaction mixture. Oxidation of [{PtII(NO2)2(μ-CH3CO 2)}2]2- with NO2 formed in the reaction mixture in the presence of oxygen provides one route to [(O2N)PtIII(NO2)2(μ-CH 3CO2)2PtIII(NO2) 2(O2CCH3)]2-. Continued heating of solutions containing these Pt(III) complexes eventually gave solutions containing [{(CH3CO2)PtIII(NO2)} 2(μ-CH3CO2)3]-.

Bindungsisomere Hexakis(selenocyanato(N)-selenocyanato(Se))-Osmate(III), [Os(NCSe)n(SeCN)6-n]3-, n = 0-3 / Bond Isomeric Hexakis(selenocyanato(N)-selenocyanato(Se)) Osmates(III), [Os(NCSe)n(SeCN)6-n]3-, n = 0-3

Six of ten possible linkage and geometric isomers of the formula [Os(NCSe)n(SeCN)6-n]3-, n = 0-3, have been obtained. The n = 0-2 complexes are prepared from the reactions of K2[OsX6] , X = Br, I, and of K2[OsO2(OH)4] in presence of ascorbic acid, with excess aqueous or methanolic KSeCN solutions at 20-40 °C. By heating the solid tetrabutylammonium salts, N-bonding of the ambident SeCN- is favoured, and the n = 3 species are formed. The complexes are separated by ion exchange chromatography and characterized by vibrational and electronic spectra. Characteristic group frequencies are: νOsSe: 183 - 216, νOsN: 224-246, νCSe(Se): 508-528, νCSe(N): 665-680, νCN: 2081-2122 cm-1.

Darstellung und Redoxverhalten aller bindungsisomeren Hexakis(thiocyanato(N)-thiocyanato(S))-osmate(III) und (IV), [Os(NCS)n(SCN)6-n]3-/2-, n = 0—6, einschließlich der Stereoisomeren / Preparation and Electrochemical Behaviour of All Bond-Isomeric Hexakis(thiocyanato(N)-thiocyanato(S))osmates(III) and (IV), [Os(NCS)n(SCN)6-n]3-/2-, n = 0—6, Including Stereoisomers

Abstract The first two complete series of all 10 possible linkage and geometric isomers of the general formula [Os(NCS)n(SCN)6-n]3-/2- have been obtained. The Os(III) complexes, some of which have been previously known, are prepared from the reactions of K2[OsX6], X = Cl. Br. I, and K2[OsO2(OH)4] with excess aqueous or methanolic KSCN solution and subsequent chromato­graphic separation on DEAE cellulose. Oxidation with Ce(IV) in acetone or methanol yields the corresponding Os(IV) compounds without changes in the ligand sphere except for n = 0, but pure salts of [Os(SCN)6]2“ are isolated by repeated recrystallization. S-bonding is less favoured in Os(IV) than in Os(III), proving that Os(IV) is the harder Lewis acid. Cyclic voltammograms of all isomers show two waves, a mainly irreversible Os(II)/Os(III) couple and a reversible Os(III)/Os(IV) couple. Characteristic shifts of the half-wave potentials of both electron transfer reactions within the series give strong evidence of π-back donation to -NCS.

Rhenium complexes with di- and tri-thiolate ligands. The synthesis and X-ray crystal structures of square pyramidal [PPh4][ReO(SCH2CH2S)2] and [NMe4][ReS(SCH2CH2S)2] and trigonal prismatic [PPh4][Re{(SCH2)3CCH3}2

The complexes [PPh4][ReO(SCH2CH2S)2](1), [NMe4][ReS(SCH2CH2S)2](3), and [PPh4][Re{(SCH2)3CCH3}2](5) have been synthesised by the reactions of K2[ReCl6] or [ReOCl3(PPh3)2] with the respective polythiol in the presence of triethylamine in methanol solution. Complex (1) crystallises in space group Pcab with a= 15.122(3), b= 18.685(4), c= 19.648(4)A, U= 5 542.02 A3, and Z= 4. Structure solution based on 2 072 independent reflections was refined to R= 0.063. Complex (3) crystallises in space group P21/c with a= 9.539(3), b= 15.123(4), c= 21.815(4)A, β= 93.58(1)°, U= 3 140.9 A3, and Z= 8. Structure solution based on 3 329 independent reflections was refined to R= 0.029. Complex (5) crystallises in space group P21/n with a= 11.506(3), b= 17.096(4), c= 18.115(4)A, β= 102.32(1)°, U= 3 488.9 A3, and Z= 4. Structure solution based on 2 380 independent reflections was refined to R= 0.0517. The [ReS(SCH2CH2S)2]– and [ReO(SCH2CH2S)2]– anions exhibit square pyramidal geometry with a terminal sulphido or oxo ligand in the apical position. The S2– ligand is derived from decomposition of the 1,2-ethanedithiolate anion with elimination of ethylene. The [Re{(SCH2)3CCH3}2]– anion has a six-co-ordinate Re atom in a trigonal prismatic co-ordination sphere. The factors responsible for the adoption of the trigonal prismatic structure are discussed.

Complexes of aminobenzylamines. part II. Complexes ofo-aminobenzylamine with palladium(II) and platinum(II)

The reactions of K2[MX4] (M = PdII or PtII and X = Cl or Br) witho-aminobenzylamine (o-aba) have been studied in neutral aqueous solutions. Two types of complexes were isolated from these studies: [MLX2] and [ML2]X2. Elemental analyses, conductivity measurements, i.r. and visible spectra suggest polymeric structures for [MLX2] with the ligand,o-aba = L, acting as a bridge, and/or mononuclear structures for [ML2]X2.