0277-5387/00/$ - see front matter q2000 Elsevier Science Ltd All rights reserved. PII S0277-5387 ( 00 ) 00321-1 Thursday Apr 13 09:55 AM StyleTag -- Journal: POLY (Polyhedron) Article: 3397 www.elsevier.nl/locate/poly Polyhedron 19 (2000) 813–819 Reaction of the diethyltin(IV) cation with pyridoxine (PN, vitamin B 6 ) in the presence of various anionic species: the crystal structure of [SnEt 2 (PN–H)]Cl Jose ´ S. Casas a , Alfonso Castineiras a , Felix Condori a , Marıa D. Couce b , Umberto Russo c , ˜ ´ ´ Agustın Sanchez a , Jose Sordo a, *, Jose M. Varela a ´ ´ ´ ´ a Departamento de Quımica Inorganica, Universidade de Santiago de Compostela, 15706 Santiago de Compostela, Galicia, Spain ´ ´ b Departamento de Quımica Inorganica, Universidade de Vigo, Vigo, Galicia, Spain ´ ´ c Dipartimento di Chimica Inorganica, Metallorganica ed Analitica, Universita di Padova, Padua, Italy ` Received 1 November 1999; accepted 28 January 2000 Abstract The reaction of the diethyltin(IV) cation with pyridoxine (PN, vitamin B 6 ) in 80:20 (v/v) ethanol–water mixtures containing NO 3 y and Cl y , NO 3 y and AcO y or Cl y and AcO y ions in various molar ratios was investigated. The compounds [SnEt 2 (PN–H)]Cl (1), [SnEt 2 (PN– H)](NO 3 )P2H 2 O (2) and [SnEt 2 (PN–2H)] (3) were isolated. These compounds were characterized by IR, Raman and Mossbauer ¨ spectroscopy and EI and FAB mass spectrometry. The structure of compound 1, determined by X-ray diffraction, consists of dimeric [SnEt 2 (PN–H)] 2 2q units (in which two bridging-chelating hydrogen pyridoxinate anions link Sn atoms with coordination number five) and hydrogen-bonded Cl y ions. The behaviour of these compounds in DMSO-d 6 and DMF-d 7 was studied by NMR spectroscopy. q2000 Elsevier Science Ltd All rights reserved. Keywords: Crystal structures; Diethyltin; Pyridoxine 1. Introduction The wide range of industrial applications of organotin com- pounds [1] has led to increasing concern about their presence in the environment and, as a consequence, to an increase in research aimed at determining the species generated by their hydrolysis [2–5]. Also, biological considerations such as the possible use of organotin compounds as antitumour agents [6] have led to increased study of the interactions of their cations with ligands of biological significance in water or mixtures of water and organic solvents [7–13]. Although most work on the hydrolysis and thermodynamics of organo- tin has concerned the dimethyltin(IV) cation [2–5,7–13], recent studies have used the diethyl and dibutyl cations [14– 17], finding that for a given ligand the stability of the species present in solution depends on the nature of R in SnR 2 2q . As part of our work on the interactions of diorganotin compounds with vitamins in aqueous or organo-aqueous * Corresponding author. Tel.: q34-981-594-636; fax: q34-981-594-912; e-mail: qijsordo@usc.es media [18,19], we have previously studied [20] the inter- action of the dimethyltin(IV) cation with pyridoxine (2- methyl-3-hydroxy-4,5-bis(hydroxymethyl)pyridine, PN), one of the recognized forms of vitamin B 6 [21], in ethanol– water containing NO 3 y and Cl y , NO 3 y and AcO y or Cl y and AcO y in various molar ratios; the presence of these anions enabled us to prepare complexes of SnMe 2 2q with both di- and mono-deprotonated pyridoxine, Cl y and NO 3 y acting as counterions in the latter case. We now report the results of an analogous study using the diethyltin(IV) cation, and describe the crystal structure of one of the compounds isolated, [SnEt 2 (PN–H)]Cl.