New bis-o-benzosemiquinonato tin(IV) complexes Ekaterina V. Ilyakina a,⇑ , Andrey I. Poddel’sky a , Alexandr V. Piskunov a , Nikolay V. Somov b , Gleb A. Abakumov a , Vladimir K. Cherkasov a a G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina 49, 603950 Nizhniy Novgorod, GSP 445, Russia b Nizhniy Novgorod State University, Physical Faculty, Building 3, Gagarina Av. 23, 603950 Nizhniy Novgorod, Russia article info Article history: Received 25 January 2012 Received in revised form 21 August 2012 Accepted 22 August 2012 Available online 31 August 2012 Keywords: Tin(IV) o-Benzosemiquinone Radical-anion EPR spectroscopy X-ray analysis abstract New bis-o-benzosemiquinonato tin(IV) complexes (3,6-SQ) 2 SnCl 2 , (3,6-SQ) 2 SnBr 2 and (3,6-SQ) 2 SnPh 2 (3,6-SQ is radical-anion 3,6-di-tert-butyl-o-benzosemiquinone) were synthesized by different methods. The reaction of tin(IV) catecholates (3,6-Cat)SnX 2 2THF (X = Cl, Br) with nitrogen(IV) oxide leads to EPR-active six-coordinated mono-o-benzosemiquinonato complexes of (3,6-SQ)SnX 2 (NO 2 )THF type which undergo symmetrization to the corresponding diradical bis-o-benzosemiquinonato species (3, 6-SQ) 2 SnX 2 . Diphenyltin(IV) catecholate (3,6-Cat)SnPh 2 THF reacts with Br 2 ,I 2 and NO 2 to give five-coor- dinated species (3,6-SQ)SnPh 2 X (X = Br, I, NO 2 ) which transform to bis-(o-benzosemiquinonato)diphenyl- tin(IV) (3,6-SQ) 2 SnPh 2 . The molecular structures of (3,6-SQ) 2 SnBr 2 and (3,6-SQ) 2 SnPh 2 were determined by X-ray analysis. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction The coordination chemistry of tin(IV) complexes containing re- dox-active o-quinonato ligands is rapidly developing [1]. Despite this, there are only two examples of bis-o-semiquinonato tin(IV) complexes which have been isolated and characterized by physico- chemical methods [2]. Some techniques to synthesize tin(IV) com- plexes, based on o-quinonato ligands, such as interaction of tin salts with o-quinones and o-semiquinonato alkali metal or thal- lium derivatives, as well as fixation of small molecules, for example halogens, by catecholate tin(IV) complexes are well known at pres- ent [3]. However, neither of these methods, nor a new method – disproportionation – has been exploited to synthesize tin(IV) bis- o-semiquinolates. In this paper, we report the synthesis of new bis-o-benzosemiquinonato tin(IV) complexes, along with physico- chemical and EPR investigations of these compounds. 2. Experimental Infrared spectra of complexes were recorded in the 400– 3500 cm 1 range on a FSM-1201 spectrophotometer in Nujol mulls and reported in cm 1 . X-band EPR spectra were recorded on Bruker EMX (working frequency 9.7 GHz) spectrometer. The g i values were determined using DPPH as the reference (g i = 2.0037). HFC constants were obtained by simulation with the WINEPR SIMFONIA Soft- ware (Bruker). X-ray diffraction data for 8 and 13 were collected using Oxford Diffraction (Gemini S) diffractometer with graphite monochromat- ed Mo-Ka radiation (l = 0.71073 Å) and with CCD detector Sap- phire III in the x-scan mode. X-ray data on samples 8 and 13 were collected at temperature 100 K. The crystal structure was solved by direct methods (SHELX97) [4] and refined by full matrix method (WINGX and SHELX97) [5]. The reflection data were processed using the analytical absorption correction algorithm [6]. All non- hydrogen atoms were refined with anisotropic correction. All H atoms were placed in calculated positions and refined in the ‘‘rid- ing-model’’ (U iso (H) = 1.2U eq (carbon) A 2 for aromatic hydrogen and 1.5U eq (carbon) A 2 for alkyl hydrogen). The follow minimal R 1 -factors obtained for 8 and 13 correspond to R 1 = 0.0346 and 0.0399, respectively. The selected bond distances and angles for 8 and 13 are given in Table 1. Table 2 summarizes the crystal data and some details of the data collection and refinement. The 3,6-di-tert-butyl-o-benzoquinone was obtained using method described in [7a]. Other starting reagents were purchased in Aldrich. Solvents were purified following standard procedures [7b]. All manipulations on complexes were performed under conditions excluding air oxygen and moisture. (3,6-Di-tert-butyl- o-benzosemiquinonato)tallium(I) ((3,6-SQ)Tl, 1) [8], bis-(3, 6-di-tert-butylcatecholato) tin(IV) ditetrahydrofuranate ((3,6- Cat) 2 Sn2THF, 2) [1c], (3,6-di-tert-butylcatecholato)dichlorotin(IV) 0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ica.2012.08.018 ⇑ Corresponding author. Tel.: +7 831 462 76 89; fax: +7 831 462 74 97. E-mail address: ekaterin_from_nn@bk.ru (E.V. Ilyakina). Inorganica Chimica Acta 394 (2013) 282–288 Contents lists available at SciVerse ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica