Thiocyanate complexes are widely used for photo metric and extraction and photometric determina tions of Co 2+ , Fe 3+ , Bi 3+ , Mo 5+ , W(VI), Mo(VI), and Nb as oxo niobium thiocyanate [1,2]. Thiocyanate ions can bind to metals either through nitrogen (isothiocyanate binding mode) or through sulfur (thiocyanate binding mode) [2,3]. In most published papers [4][5][6][7], Raman or IR spectrometry were used to study metal thiocyanates in the crystalline state, in non aqueous solvents, or as melts.UV and IR spectrometry of aqueous solutions of d metal thiocyanates is fragmentary. In [8,9], aqueous solutions of mercury(II) thiocyanate were experimen tally studied by Raman, IR, and UV spectrometry and also by the density functional theory method.The structure and the IR absorption spectra of potassium, ammonium, Ag(I), Zn(II), and Cd(II) thiocyanates in the crystalline state and in aqueous solutions were reported in [4,[10][11][12]. Meanwhile, no data on the UV spectra of aqueous solutions of Co(II), Zn(II), Cd(II), Fe(II), Mn(II), or Ni(II) thiocyanates or the IR spectra of solutions of Co(II), Fe(II), Mn(II), or Ni(II) thiocyanates are available from the literature.The interest in detailed and systematic investiga tion of aqueous solutions of d metal thiocyanates is also due to the fact that the coordination mode of SCN -largely determines the course of anion exchange extraction of metal thiocyanate complexes by quater nary ammonium salts, which can be used for separa tion and preconcentration [13]. As a result of studies of the anion exchange extraction of thiocyanate metal complexes from aqueous solutions with didecylami noethylene β tridecylammonium salts dissolved in decane, the following extraction series for ≤ 5 × SCN c − 10 -2 mol/L were composed: > > > > for higher SCN -concentrations (up to 0.5 mol/L): > > > > However, in previous studies, most con clusions about the influence of the structure of thiocy anate complexes on the anion exchange extraction were made based on general theoretical views.This publication reports a systematic study of aque ous solutions of Co(II), Zn(II), Cd(II), Fe(II), Mn(II), Ni(II), and Hg(II) thiocyanates by UV, visi ble, and IR spectrometry. As a result, the coordination mode of SCN -ions to metal ions was elucidated, and an explanation for the relationship between the struc ture and anion exchange extraction of thiocyanate complexes was proposed. The absorption maxima (λ max ) and molar extinction coefficients (ε) for thiocy anate complexes in the visible and UV regions were proposed. EXPERIMENTALCommercial reagent grade or analytical grade Co(II), Zn(II), Cd(II), Fe(II), Mn(II), and Ni(II) chlorides, Hg(NO 3 ) 2 , and KNCS were used. The con centration of metal ions in solutions was 0.01 mol/L; the KNCS concentration varied from 0.1 mol/L to higher values.IR spectra were measured on an InfraLUM FT 02 FT IR spectrometer in the 2300-400 cm -1 range of wave numbers and treated with the SpectraLUM applied program. The spectral resolution was 1 cm -1 . The error of measurements di...

Введение В предыдущих работах [1, 2] была изучена селективность Со(SCN) 4 2-−селективного электрода на основе 3.4.5-трисдодецилоксибензилтриметиламмония как в отсутствие в фоне СоCl 2 , так и на фоне постоянной концентрации СоCl 2. В качестве мешающих были выбраны наиболее гидрофобные минеральные ионы-перхлораты, которые занимают первое место в ряду селективности Гоффмейстера ClO 4 − >SCN − >I − >NO 3 − >Br − >NO 2 − >-Cl − >SO 4 2− и в присутствии которых разработанные электроды имеют низкую селективность к SCN − , и дополнительно нитрат-ионы. Получены следующие значения коэффициентов потенциометрической селективности K Pot SCN−,ClO4− : в отсутствие в растворе СоCl 2 7.6•10-1 ; на фоне 0.01 моль/л СоCl 2-2.9•10-2 ; на фоне 0.1 моль/л СоCl 2-1.5•10-3 ; на фоне 1.0 моль/л СоCl 2-2.6•10-4 ; на фоне 3.5 моль/л СоCl 2-8.8•10-5. В данной работе изучена селективность Zn(NCS) 4 2-−СЭ к SCNв присутствии СlО 4 − и NO 3 − , а также Со(SCN) 4 2-−СЭ к SCNв присутствии NO 3 −. Определение K Pot SCN−,ClO4− и K Pot SCN−,NO3− проводили не только для электродов на основе 3 .4.5-трисдодецил ок сибензилтриметиламмония (ТМ), но для стерически затрудненного 95 The effect of background concentration of ZnCl 2 and CoCl 2 on selectivity of SCN-ion selective electrodes based on trimethyl-and trinonyloctadecylammonium salts (QAS) with Zn(NCS) 4 2and Co(SCN) 4 2have been studied in the presence of interfering nitrate and perchlorate ions. Introduction of ZnCl 2 and CoCl 2 into solution fixes zinc and cobalt coming out of the membrane as a thiocyanate complexes, which have a high affinity towards anion exchange QAS acidocomplexes compared with competing anions. Introduction in solution 3.5 mol/l CoCl 2 increases the selectivity to SCN − on 4 orders, the introduction in solution 5.0 mol/l ZnCl 2 increases the selectivity for SCN − on 5 orders for electrodes based on trimethyl QAS. It is shown that the trinonyloctadecylammonium based electrodes increase their selectivity on 6 and 5 orders, for Zn(NCS) 4 2-(5.0 mol/l background ZnCl 2) and Co(SCN) 4 2-(3.5 mol/l background CoCl 2), respectively .

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