Preference of di-n-butyltin IV compounds to build OÁÁÁSn bonds in fused rings with five-six members Norberto Farfa ´n a, * , Teresa Mancilla a , Rosa Santillan a , Atilano Gutie ´rrez b , Luis S. Zamudio-Rivera c , Hiram I. Beltra ´n c, * a Departamento de Quı ´ mica, Centro de Investigacio ´ n y de Estudios, Avanzados del Instituto Polite ´cnico Nacional, Apdo, Postal 14-740, 07000 Me ´xico, DF Me ´xico b Laboratorio de Resonancia Magne ´tica Nuclear, Universidad Auto ´ noma Metropolitana, San Rafael Atlixco 186 Col. Vicentina, Unidad Iztapalapa, 09340, DF, Me ´xico c Programa de Ingenierı ´a Molecular, Instituto Mexicano del Petro ´ leo, Eje Central La ´ zaro Ca ´ rdenas No. 152, Apartado Postal 14-805, 07730 Me ´xico Received 5 May 2004; accepted 20 July 2004 Available online 11 September 2004 Abstract The reaction of salicylaldehyde (1), o-aminophenols (2a–2f), and di-n-butyltin IV oxide (3) to give six di-n-butyltin IV compounds (4a–4f) was achieved in good yields. All compounds were characterized by 1 H, 13 C, 15 N, 119 Sn NMR, mass spectrometry, IR, ele- mental analysis and in the case of compounds 4a, 4b, 4d and 4e by X-ray diffraction analysis. Compound 4a crystallized with trig- onal bipiramidal (TPB) geometry surrounding the tin atom while 4b and 4e crystallized as dimeric molecules joined by two OÁÁÁSn bonds with distorted octahedron (DOC) geometry. The X-ray structure of 4d presents one cocrystallized monomeric TBP with one dimeric DOC molecule. Correlations of r Hammett vs. spectroscopic values were found for 4a–4b and 4d–4f, indicating the substituents in the aromatic ring derived from o-aminophenol serve as modulators of the OÁÁÁSn supramolecular interaction. The OÁÁÁSn bond formation is selective for the five-membered ring oxygen atom. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Di-n-butyltin IV ; Multinuclear NMR; X-ray structures; Sigma Hammett; Schiff base 1. Introduction Since Pedersen, Lehn and Cram were awarded the Nobel Prize in 1987 ‘‘for their development and use of molecules with structure-specific interactions of high selectivity’’ [1], many scientific as well as technological aspects have been approached within the realm of Supramolecular Chemistry [2–6]. Our recent work in tin chemistry is directed to the X–SnÁÁÁY bond forma- tion (where X and Y are mainly N or O), this bond has the ability to build supramolecular aggregates of trimeric, hexameric, oligomeric and polymeric states [7–10]. Therefore, elucidation of the supramolecular bonding of molecules containing tin should provide basis to understand the recognition processes with natu- ral receptors and explain their activities as anticancer agents and towards bacteria [11,12]. A crystallographic search of the CCDC data base [13] reveals that tin IV compounds with di-n-butyl and diphe- nyl substituents constructed from rigid tridentate lig- ands, result in formation of monomeric species, both in solution and in the solid-state [14–17]. Reported X- ray structures of dimeric tin IV compounds are scarce and refer mainly to bidentate ligands containing 6:4:6 fused rings (Scheme 1) [14,18–23]. The use of tridentate 0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2004.07.053 * Corresponding authors. E-mail addresses: jfarfan@mail.cinvestav.mx (N. Farfa ´n), hbel- tran@www.imp.mx (H.I. Beltra ´n). Journal of Organometallic Chemistry 689 (2004) 3481–3491 www.elsevier.com/locate/jorganchem