Athos Bellomo

Formation of copper(II), zinc(II), silver(I) and lead(II) ferrocyanides

The factors influencing the formation of metal hexacyano-ferrate(II) complexes have been examined and the experimental conditions leading to formation of M(2)Fe(CN)(6), and K(2)M(3)[Fe(CN)(6)](2) have been studied, where M is Cu(II) or Zn(II); Ag(I) yields Ag(4)Fe(CN)(6). and KAg(3)Fe(CN)(6) and Pb(II) yields only Pb(2)Fe(CN)(6). Measurements made at constant ionic strength obtained by addition of K(2)SO(4) show how the potassium ion affects the stabilization of the complexes. The free energy changes and K(sp) values for the complexes have been calculated.

Thermodynamics of complex formation of Ag(I). VI: Ag(I)-thiocarbonyl ligand systems in aqueous solution

Abstract The formation of complexes between Ag(I) and substituted thioureas has been studied by potentiometric measurements in aqueous solution at μ = 0 and various temperatures. Under these experimental conditions, three-coordinated complexes are formed with all the ligands. The influence of the substituents is mainly an “external” effect and causes a more positive Δ H and Δ S value for the formation of complexes with substituted thioureas compared to those with thioureas.

Formation of ferrocyanides—IV: Th(IV), Nd(III), UO2(II) and Hg(II)

The stoichiometry of the reaction between ferrocyanide and thorium, neodymium, uranyl ion and mercury(II) has been investigated. The first three give single products irrespective of the order of addition of the reagents, but the last does not. If mercury(II) is added to ferrocyanide Hg(2)Fe(CN)(6) is obtained, but if ferrocyanide is added to mercury(II) various cyanide complexes of mercury are formed. The K(sp) values for the precipitates are reported.

Formation and thermodynamic properties of mixed complexes of Cd(II) with SCN2H4 and C−, Br−, I− as ligands☆

Abstract Thermodynamic parameters for in-water-formation of mononuclear complexes of cadmium-halide-thiourea systems, calculated by means of potentiometric measurements at different temperatures and at μ = 1 for KNO 3 , are reported.

Formation and thermodynamic properties of Ag(I) complexes with S2O32−, SCN2H4 and SCN− as ligands

Abstract Changes in thermodynamic functions ΔG°, ΔH° and ΔS° for the formation of Ag(I) complexes of general formulae: Ag ( S 2 O 3 ) n ( SCN 2 H 4 ) m ( SCN ) p 1−2 n − p and the diagrams defining the range of existence of the following complexes: Ag ( SCN 2 H 4 ) m ( SCN ) p 1− p and Ag ( S 2 O 3 ) n ( SCN ) p 1−2 n − p in an aqueous medium at μ = 1 for KNO 3 , are reported. The relations between thermodynamic parameters for coordination or displacement of S 2 O 3 2− , SCN − or SCN 2 H 4 ligands are discussed.

Formation of ferricyanides-I silver(I), copper(II) and cadmium(II).

With potassium ferricyanide copper(II) forms KCu(10),[Fe(CN)(6)](7) quantitatively in 0.5M potassium nitrate medium. Cadmium forms Cd(3)[Fe(CN)(6)](2) if the ferricyanide is added to the cadmium solution in absence of extra potassium, and KCd(10)[Fe(CN)(6)](7) if potassium is added first, or if the cadmium solution is added to the ferricyanide. Silver forms Ag(3)Fe(CN)(6) only.

Formation and thermodynamic properties of complexes of Ag(I) with thiourea as ligand

A potentiometric study has been made of the Ag(I)CSN(2)H(4)H(2)O system. Mathematical analysis of the formation functions reveals the existence of the complexes AgCSN(2)H(+)(4), Ag(CSN(2)H(4))(+)(4), Ag(CSN(2)H(4))(+)(3) and Ag(CSN(2)H(4))(+)(4) for which the stability constants have been calculated at different ionic strengths and temperatures. No evidence was found for the formation of polynuclear complexes.

Thermal analysis of some cyano compounds

The thermal behaviour of the title compounds in static air has been investigated by conventional thermal analysis (TG and DSC) and infrared spectroscopy of the solid residues at various temperatures.The following points are demonstrated:i)the presence ofan alkali metal cation (e.g. Na(I) or K(I)) appears to be a necessary, but not sufficient condition for the intermediate formation of cyanate in the oxidation of Fe(CN)6n−(n=3 or 4);ii)a multivalent cation favours a hydrolytic mechanism, with preferential evolution of HCN rather than H2O;iii)the thermally induced reduction of Cu(II) to Cu(I) occurs simultaneously with the linkage isomerism of CN−, with the resultant formation of Cu(I)-CN− complexes.ZusammenfassungDie thermischen Eigenschaften von folgenden Komplexen wurden untersucht: Na4Fe(CN)6 · 10H2O, K2Cu3[Fe(CN)6]2·xH2O, K2Zn3[Fe(CN)6]2·xH2O und Pb2Fe(CN)6. Folgendes wird verdeutlicht: i) die Gegenwart eines Alkalimetallkations (z. B. Na(I) oder K(I)) scheint eine notwendige, aber nicht ausreichende Bedingung für die Bildung von intermediärem Zyanat bei der Oxydation von Fe(CN)6n− (mitn=3 oder 4) zu sein; ii) ein multivalentes Kation begünstigt einen hydrolytischen Mechanismus, bei dem eher HCN als H2O gebildet wird; iii) parallel zur thermisch induzierten Reduktion von Cu(II) zu Cu(I) findet auch die Bindungsisomerisierung von CN− statt, wodurch es zur Bildung von Cu(I)-CN− Komplexen kommt.РезюмеПредставлены следую щие особенности термического поведе ния некоторых цианос оединений: а) присутствие каких-л ибо щелочных катионо в (напр, натрия или калия) долж но быть неоходимым, но недост аточным условием обр азования цианата, как промежут очного продукта, при окислении Fe(CN)6/n сп=3 и ли 4, б) многовалентных катион способствует гидролитическому ме ханизму с предпочтит ельным выделением скорее HCN, че м Н2О и в) термически наведен ное восстановление двухвалентной меди д о одновалентной прои сходит одновременно с изоме рией связи CN−, что прив одит к образованию комплек сов Cu(I)-CN−.

Formation of Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Ag(I) and Cd(II) hexacyanocobaltates.

A study is reported of the formation of Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Ag(I) and Cd(II) hexacyanocobaltates. The results show that the precipitates form by reaction of the metal ions with KCo(CN)(6)(2-) ion-pairs in 1:1 ratio, followed by solid phase transformations.

Formation of nickel, cobalt, manganese and cadmium ferrocyanides

Potentiometric and solubility studies have been made of the ferrocyanides of nickel, cobalt, manganese(II) and cadmium both in the presence and absence of potassium. The K(3p),DeltaG degrees , DeltaH degrees and DeltaS degrees values are reported.