ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2014, Vol. 40, No. 4, pp. 205–215. © Pleiades Publishing, Ltd., 2014. Original Russian Text © A.V. Piskunov, I.N. Meshcheryakova, G.K. Fukin, I.V. Smolyaninov, N.M. Khamaletdinova, O.V. Kuznetsova, 2014, published in Koordinatsionnaya Khimiya, 2014, Vol. 40, No. 4, pp. 205–215. 205 INTRODUCTION This work continues the studies of nontransition metal complexes based on the redox-active ligands actively developed in recent decades. The develop- ment of this direction in the chemistry of coordination and organometallic compounds is urgent and promis- ing as demonstrated by examples of an unusual reac- tivity of this class of compounds (in particular, in redox transformations). Among the most interesting results are the discovery of the unique ability of the antimony(V) catecholate and amidophenolate com- plexes to reversibly add oxygen [1–5], nitrogen mon- oxide fixation by the lead(II) and zinc(II) catecholate derivatives [6], the activation of the triple bond in ter- minal alkynes in the reactions with the aluminum(III) and gallium(III) compounds based on the acenaph- thenediimine ligand [7–9], and the oxidative addition of alkyl halides to the indium(III) bis(amidopheno- late) complexes [10]. The above examples concern the metal compounds containing redox-active ligands in the reduced form. However, ligands of this type can exist in the coordination sphere of metal atoms in the neutral form as well. For example, the zinc(II) and indium(III) compounds containing the coordinated o-benzoquinone or o-iminobenzoquinone molecule were described [11, 12]. These complexes act in reac- tions as oxidants rather than reducing agents. The oxi- dation ability of the redox-active ligand neutrally bound to the metal atom is noticeably enhanced com- pared to that of free o-benzoquinone (o-iminobenzo- quinone). This work is devoted to the synthesis and study of the physicochemical properties of the tin(IV) com- plexes based on the p-benzoquinone ligand addition- ally functionalized by the hydroxy group (LH). These compounds also act as oxidants in redox processes, and the study of their redox potentials and redox trans- formations seems to be very interesting. In addition, the study of these complexes is urgent from the view- point of prospects of their use as biologically active substances. It has recently been shown that the organ- otin compounds based on dihydroxy-9,10- anthracenedione and hydroxy-1,4-naphthoquinone [13–15] are the closest analogs of the compounds studied by us and exhibit a high anticancer activity. EXPERIMENTAL The reagents used were synthesized according to known procedures: LH [16], LSnPh 3 [16], ClSnMe 3 , Cl 2 SnMe 2 , Cl 2 SnEt 2 , Cl 2 Sn(Bu n ) 2 (Bu n = n-butyl), and Cl 2 SnPh 2 [17]. NMR spectra were detected in a CDCl 3 solution at 20°C on Bruker DPX-200 (200 MHz) and Bruker Avance III (400 MHz) instruments using tetramethyl- silane as an internal standard. Tin(IV) Complexes Based on 2-Hydroxy-3,6-Di-tert-Butyl-para- Benzoquinone: Syntheses, Structures, and Electrochemical Behavior in Solution A. V. Piskunov a, *, I. N. Meshcheryakova a , G. K. Fukin a , I. V. Smolyaninov b , N. M. Khamaletdinova a , and O. V. Kuznetsova a a Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, ul. Tropinina 49, Nizhni Novgorod, 603950 Russia b Research Group of Toxicology, Department of Aqua Culture and Water Resources, Southern Scientific Center, Russian Academy of Sciences, Astrakhan, Russia *e-mail: pial@iomc.ras.ru; thiophen@mail.ru Received July 23, 2013 Abstract—A series of new tin(IV) complexes based on 2-hydroxy-3,6-di-tert-butyl-para-benzoquinone (LH) of the general formula L 2 SnR 2 (R = Me (I), Et (II), Bu n (III), Ph (IV)) and LSnMe 3 (V) were synthe- sized. The obtained compounds were characterized by IR and 1 H, 13 C and 119 Sn NMR spectroscopy and ele- mental analysis. The X-ray diffraction analysis was carried out for complexes L 2 Sn(Bu n ) 2 (III) and LSnMe 3 (V). The low-frequency region of the IR spectra, which has not earlier been studied in detail, was interpreted for compounds I–V and previously described complex LSnPh 3 (VI). The electrochemical properties of LH and related tin complexes I–VI were studied. The nature of the hydrocarbon groups at the metal atom affects the stability of the intermediates formed in the electrochemical reactions. DOI: 10.1134/S1070328414040083