Research Article 2- Inorganic Chemistry

Spectroscopic Evidence for the pH Sensitivity and Anion Trapping Capability of
N,N-ethylenebis(acetylacetoneiminato)copper(II) Complex

A.M.K.S.P Adhikari ,M.Y.Udugala-Ganehenege *;
Department of Chemistry, Faculty of Science, University of Peradeniya

Abstract

A shiny crystalline purple colour N,N-ethylenebis(acetylacetoneiminato)copper(II) complex synthesized by template synthesis shows some interesting acid-base properties and capability of binding anions. Single crystal X-ray crystallographic, XRD, UV, IR and CV data were used to characterize the compound. Interestingly, the complex is purple at pH > 7 and colourless in pH <> 7 shows a band at 540 nm. This band disappears and a new band appears around 820 nm giving an isobestic point at 680 nm with the addition of H+ ions into an ethanolic solution of the compound. Interestingly, the band around 540 nm reappears and the solution colour turns to purple again with the addition of OH- ions into the same solution. Stepwise addition of SCN- and Br- to the solution separately at pH < 2 shows an appearance of a new band at 795 nm and 790 nm respectively with the disappearance of the band at 540 nm. This red shift of the d-d band together with the intensity decrease at pH < 2 may be due to the protonation of the ligand environment bonded to the Cu2+ center by decreasing the crystal field stabilization energy (CFSE) of the complex and increasing the symmetry of the system. The blue shift of the d-d band together with the intensity increase with the addition of various anions to the solution at pH < 2 may be due to the CFSE change with the coordination of anions to Cu2+ center and decreasing the symmetry of the system.

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Research Article 1- Inorganic Chemistry

SYNTHESIS OF A NOVEL COPPER (II) COMPLEX THAT SHOWS REMARKABLE AFFINITY FOR SILVER (I) IONS.

A.M.K.S.PRABHATH ADHIKARI, M.Y.UDUGALA-GANEHENEGE*;
Department of Chemistry, Faculty of Science, University of Peradeniya.

ABSTRACT

A novel blackish nanostructured complex of copper(II) coordinated to both dithiooxamide (rubeanic acid) and acetyl acetone has been synthesized by template synthesis. The complex is extremely insoluble in almost all the solvents so that infrared (IR) data, X-ray diffraction (XRD) data, hardness measurements and melting points were used to characterize the complex. Measurements revealed that the melting point is above 280 ºC and hardness is in between 2.5 and 3 in the Mohs scale. The calculated particle size based on the XRD data of the complex is 13.2 nm and is less than that of dithioxamido complex of Copper(II). IR data of the complex indicate the increase in N-H frequencies in metalloderivative compared to the free dithiooxamide by 100 cm-1revealing the N-end of dithiooxamide is primarily bonded to the metal center. An ion-exchange study shows a remarkably specific affinity of the complex only for Ag+ ions and not for Pb(II), Cd(II), Ni(II) and Zn(II) ions. Atomic absorption spectroscopic(AAS) analysis of the effluent collected by passing a solution of Ag(I) ions through a column packed by the copper(II) complex shows a trapping of Ag(I) ions followed by a release of Cu(II) ions. These results demonstrate the application of the complex for specific trapping of some noble ions only.

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