Complexes of tin(IV) halides and diorganotin(IV) dihalides with 3,5-dimethyl-1-(2 '-pyridyl)pyrazole
INORGANICA CHIMICA ACTA
Authors: Alvarez-Boo, P; Casas, JS; Castineiras, A; Couce, MD; Freijanes, E; Furlani, A; Russo, U; Scarcia, V; Sordo, J; Varela, M
Abstract
3,5-Dimethyl-1-(2'-pyridyl)pyrazole (DMPP) reacts with SnX4 and R2SnX2 (X=Cl, Br, I; R = Me, Et, Bu, Ph) to yield adducts of types [SnX4(DMPP)] and [SnR2X2(DMPP)], respectively. The structure of [SnEt2Br2(DMPP)] has been determined by X-ray diffractometry. The crystal consists of discrete [SnEt2Br2(DMPP)] molecules with the metal atom octahedrally coordinated to two Br atoms [Sn-Br = 2.631(3), 2.703(3) Angstrom; Br-Sn-Br = 98.00(10)degrees], two ethyl carbons [Sn-C = 2.11(3), 2.143(19) Angstrom; C-Sn-C = 172.3(11)degrees] and the two donor N atoms of the ligand [Sn-N = 2.379(16), 2.387(16) Angstrom; N-Sn-N = 66.8(6)degrees]. The IR data and Mossbauer parameters are consistent with all the organotin derivatives having, similar geometry whereas in the case of the [SnX4(DMPP)] complexes the results of both techniques support the expectation of cis stereochemistry. The H-1 NMR data indicate significant dissociation in solution. The chlorobutyl derivative exhibited significant in vitro antitumour activity against the human carcinoma cell line KB. (C) 2003 Elsevier B.V. All rights reserved.
INFORMATION FROM THE MOSSBAUER-SPECTRA OF TIN(IV) HALIDE-COMPLEXES WITH 1,3-DIETHYLTHIOUREA - A REDETERMINATION OF THE CRYSTAL-STRUCTURE OF TETRACHLOROBIS(1,3-DIETHYLTHIOUREA)TIN(IV)
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
Authors: TUDELA, D; KHAN, MA; ZUCKERMAN, JJ
Abstract
The Mossbauer quadrupole splitting of octahedral tin(IV) chloride complexes can give information about the Sn-Cl bond lenghts. As the value of d(Sn-Cl) reported previously for SnCl4(detu)2 (detu = 1,3-diethylthiourea) was too long for a complex showing a single line in the Mossbauer spectrum, we have redetermined the X-ray crystal structure, and found Sn-Cl distances which are compatible with the Mossbauer data. The compound crystallises in the centrosymmetric space group R3BAR-c, and the structure is disordered about a crystallographic two-fold axis passing through Sn and two Cl atoms. The disorder does not allow the unambiguous distinction between a cis or trans structure by X-ray crystallography, but IR and Raman spectroscopies show that both SnCl4(detu)2, and the new compound SnF4(detu)2, have a cis geometry. The isomer shift values for SnX4(detu)2, are -0.04, 0.62, 0.96 and 1.21 mm s-1 for X = F, Cl, Br and I, respectively. The values for X = Cl and Br are much higher than previous values, and fully consistent with S-co-ordination by the detu ligand. The information on the donor atom in SnX4L2 complexes, which can sometimes be obtained from the Mossbauer isomer shift, is discussed.