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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By IR spectrometry thiocyanates aqueous solutions of divalent cations of cadmium, mercury, nickel, manganese, iron, zinc and cobalt were studied. It was found that cadmium (II), mercury (II), nickel (II), iron (II) thiocyanate ions coordinated by type thiocyanate, zinc (II) − according to the type isothiocyanate; cobalt (II) and manganese (II) coordination mode change depending on the concentration of potassium thiocyanate in a solution. These results are consistent with the theory of hard and soft acids and bases. Co2+ ions are intermediate acids, so they can coordinate with SCN− into two types; Zn2+ ions, although they belong to intermediate acids but have a strong affinity to nitrogen atoms, so thiocyanate group coordinated through nitrogen with Zn2+. Cations Hg2+ and Cd2+ are typical soft acids, so only coordinated SCN− ions through sulfur (as a mild base). Mn2+ ions can coordinate SCN− by two types. The effect of additives of the ammonium chloride ions on thiocyanate ions (0.5 mol/l) coordination with cobalt (II) ions was studie. With the increasing concentration of ammonium chloride in a solution a change occurs of coordination type with thiocyanate to isothiocyanate. It has been suggested that the increase in the concentration of potassium thiocyanate leads to the increase in the proportion of Co(NCS)42− and reduce the proportion of «free» water (unrelated with ions in the solution). Therefore, SCN− ions in the case Mn2+ and Co2+ oriented so that the hydrophobic sulfur atoms are external ones.Forcitation:Matveichuk Yu.V., Rakhman′ko E.M. Thiocyanate complexes of d-metals: influence of concentration of KNCS and NH4Cl on a type of coordination of SCN− ions by FTIR spectrometry. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 7. P. 34-41.

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