It was determined the chemico-analytical characteristics and composition of the complexes formed in the Mo(VI)–DOCh systems. The composition of the complexes (Mo(VI):DOCh = 1:2) was found by spectrophotometric methods (molar ratios, equilibrium shift). A probable complex chemistry was proposed based on a combination of spectrophotometric and mass- spectrometric data. It was shown that the MoO22+ cation acts as a complexing agent, and the ligand enters into the reaction in the form of an anhydrobase. It was found, that halogen-containing derivatives of MPDOCh form more intensely colored and stable complexes with Mo (VI) than MPDOCh, and the optimal pH of complexation shifts to a more acidic region. The study of the complexation of molybdenum(VI) with 6,7-dihydroxy-4-methyl-2-phenylchrome-nilium (MPDOCh) and its chlorine and bromine derivatives containing a halogen atom in 4th position in phenyl ring was shown that MoO22+ cation acts as a complexing agent, and the ligand involved into reaction in the form of an anhydrobase. The analytical characteristics of the resulting complexes were determined, and it was also noted that the halogen derivatives of MPDOCh form more intensely colored and stable complexes with Mo(VI).
2. Pyrzynska K. Determination of molybdenum in environmental samples. Anal. Chim. Acta. 2007. 590(1): 40.
3. Ivanov V.M., Kochelaeva G.A., Prokhorova G.V. Methods for Determining Molybdenum. J. Analyt. Chem. 2002. 57(9): 758.
4. Gürkan R., Aksoy Ü., Ulusoy H., Akçay M. Determination of low levels of molybdenum in food samples and beverages by cloud point extraction coupled with flame atomic absorption spectrometry. J. Food Comp. and Anal. 2013. 32: 74.
5. Oviedo J., Fialho L., Nobrega J. Determination of molybdenum in plants by vortex-assisated emulsification solidified floating organic drop microextraction and flame atomic absorption spectrometry. Spectrochim. Acta. B. 2013. 86: 142.
6. Ünal Ü., Some G. A new and very simple procedure for the differential pulse polarographic determination of ultra trace quantities of tungsten using catalytic hydrogen wave and application to tobacco sample. J. Electroanalyt. Chem. 2012. 687: 64.
7. Zarei K. Simultaneous voltammetric determination of Mo(VI) and W(VI) by adsorp-tive differential pulse stripping method using adaptive neurofuzzy inference system. J. Analyt. Chem. 2013. 68(10): 885.
8. Bednar А.J., Mirecki J.E., Inouye L.S., Winfield L.E., Larson S.I., Ringelberg D.B. The determination of tungsten, molybdenum, and phosphorus oxyanions by high performance liquid chromatography inductively coupled plasma mass spectrometery. Talanta. 2007. 72: 1828.
9. Nakano S., Kamaguchi C., Hirakawa N. Flow-injection catalytic spectrophotometic determination of molybdenum(VI) in plants using bromate oxidative coupling of p-hyd-razinobensenesulfonic acid withN-(1-naph-thyl)ethylenediamine. Talanta. 2010. 81: 786.
10. Pytlakowska K., Feist B. Spectrophotometric determination of molybdenum in the presence of tungsten using gallein and benzyldodecyldimethylammonium bromide. J. Analyt. Chem. 2013. 68(1): 39.
11. Zalov Z., Verdizade N. Extraction-spectrophotometry determination of tungsten with 2-hydroxy-5-chlorothiophenol and hydrophobic amines. J. Analyt. Chem. 2013. 68(3): 212.
12. Tsiganok L.P., Vaculich A.N., Vishnikin A.B., Koltsova E.G. Spectrophotometric determination of tungsten based on molybdotungsten isopolyanions in presence of non-ionic surfactant. Talanta. 2005. 65: 267.
13. Kulichenko S.A., Sherbina M.G. Colori-metric determination of molibdenum in cat-ionic surfactants micellar extracts. Me-thods and objects of Chem. analysis. 2012. 7(1): 39. [in Ukrainian].
14. Ekbal A.K.H. Dioxychromenols modified by cationic surfactants as reagents for some metal ion photometric determination: PhD thesis. (Odesa Phisico-chemical institute O. V. Bogatskyi, 1987). [in Russian].
15. Chebotaryov A.N., Snigur D.V., Barbalat D.О., Mykhailova A.S. Complexation of Mo(VI) and W(VI) with some derivatives of 6,7-dihydroxybenzopyrylium chloride in solution. Ukrainian Chemistry Journal. 2016. 82(11): 44.
16. Chebotaryov A.N., Shafran K. L. Sorbtion-spectrophotometric determination of molybdenumin plants matirials. Ukrainian Chemistry Journal. 2000. 66(3–4): 36. [in Russian].
17. Bulatov M.I., Kalinkin I.P. A practical guide to photometric methods. (Moscow: Himia, 1985). [in Russian].