X-ray Diffraction and Gradient-Assisted 2D 1H−119Sn HMQC NMR Studies on the Structure of Condensation Complexes of Salicylaldoxime and Dimethyltin(IV) Oxide

Structural and spectral studies of N-(3-hydroxypyridine-2-yl)salicylideneimine and N-(3-hydroxypyridine-2-yl)-5-bromosalicylideneimine and their dimethyltin(IV) complexes

N-(3-hydroxypyridine-2-yl)salicylidineimine (1), N-(3-hydroxypyridine-2-yl)-5-bromo salicylideneimine (2) and their diorganotin(IV) complexes formulated as Me2Sn(OC6H4CH=NC5H3NO) (3) and Me2Sn(OC6H3BrCH=NC5H3NO) (4) were prepared and characterized by 1H-NMR, IR, mass spectroscopy and single crystal x-ray diffraction study. The crystal structures of 3 [orthorhombic, Pbna (no 60); a = 10.439(1) Å, b = 13.388(3) Å, c = 19.340(2) Å, Z = 4; V = 2703(1) Å3] and 4 [monoclinic, P21/a (no 14); a = 7.528(4) Å, b = 16.576(7) Å, c = 12.017(7) Å, β = 97.97(5), Z = 4; V = 1485(1) Å3] have been solved by standard methods and refined by full-matrix least squares (carried out on F 2) to R values of 0.066 and 0.046 respectively. The studied tin(IV) complexes (3 and 4) exhibit the distorted trigonal-bipyramidal geometries around Sn atoms, separately. The tautomeric effects of ligands and the substitution of Br atom to the common molecular structure were discussed beside of the coordination geometries of 3 and 4.

Tin(IV) cyanoximates: synthesis, characterization, and cytotoxicity

In recent years, numerous organotin(IV) derivatives have exhibited remarkable cytotoxicity against several types of cancer. However, the properties of the cyanoxime-containing organotin(IV) complexes are unknown. Previously, it has been shown that cyanoximes displayed an interesting spectrum of biological activity ranging from growth-regulation to antimicrobial and pesticide detoxification actions. The work presented here attempts to combine the useful properties of both groups of compounds and investigate the likely antiproliferating activity of the new substances. A series of 19 organotin(IV) complexes, with nine different cyanoxime ligands, were anaerobically prepared by means of the heterogeneous metathesis reaction between the respective organotin(IV) halides (Cl, Br) and ML (M=Ag, Tl; L=cyanoximate anion), using an ultrasound in the CH3CN at room temperature. The compounds were characterized using spectroscopic methods (UV-visible, IR, 1H,13C NMR, 119Sn Mössbauer) and X-ray analysis. The crystal structures of the complexes revealed the formation of two types of tin(IV) cyanoximates: mononuclear five-coordinated compounds of R4-xSnLx composition (R=Me, Et, n-Bu, Ph; x=1, 2; L=cyanoximate anion), and the tetranuclear R8Sn4(OH)2O2L2 species (R=n-Bu, Ph). The latter complex contains a planar [Sn4(OH)2O2]2- core, consisting of three adjacent rhombs with bridging oxo and hydroxo groups. The tin(IV) atoms are five-coordinated and have distorted trigonal-pyramidal surrounding. This is the first instance when the organic anions were found to act as monodentate O-bound planar oxime ligands. All of the compounds were studied in vitro for antiproliferating activity, using human cervical cancer HeLa and WiDR colon cancer cell lines; cisplatin was used as a positive control substance. The two dibutyltin(IV) cyanoximates showed cytotoxicity similar and greater to that of cisplatin.

Complexation of triorganotin derivatives of [18]crown-6- and [15]crown-5-(benzo-4-carboxylate) with alkali thiocyanates

Investigations of the simultaneous complexation of tri-n-butyltin and triphenyltin derivatives of [18]crown-6- or [15]crown-5-(benzo-4-carboxylate) by the anion and cation from NaSCN or KSCN are reported. The crystal structure of [Na+ is included in [15]crown-5-C6H3-4-COOSn(C6H5)3NCS]-], 4 NaSCN, displays an unusual zwitterionic nature with one intramolecular charge separation characterized by an Na-Sn distance of 9.29(1) A, and several intermolecular charge separations, the shortest being 5.48(1) A. Similar distances (9.70(2), 9.28(2), intramolecular; 5.40(2) and 5.41(2) A, shortest intermolecular) are observed in the more complicated structure of the corresponding [18]crown-6-(benzo-4-carboxylate) derivative, 3 NaSCN, with two independent molecules in the asymmetric unit. For the tri-n-butyltin analogues 1 and 2, complex equilibria were observed in acetone and unraveled by variable temperature 13C, 117Sn. and 23Na NMR studies. Their complexes with KSCN and NaSCN undergo decomposition in acetone solution, as evidenced by the transformation of [K+ is included in [18]crown-6-[C6H3-4-COOSn(nBu)3NCS]-], into tri-n-butyltin isothiocyanate and a novel dimeric potassium [18]crown-6-(benzo-4-carboxylate), the structure of which was elucidated by X-ray diffraction analysis.

Reactions of [t-Bu(2)SnO](3) with [t-BuX(2)Si](2) (X = F, Cl). Syntheses and Structures of Novel Stannasiloxanes and of [(t-Bu(2)FSn)(2)O](2), the First Fluorine-Containing Tetraorganodistannoxane(,)

Di-tert-butyltin oxide, (t-Bu(2)SnO)(3) (1), reacts with 1,2-di-tert-butyltetrachlorodisilane, (t-BuCl(2)Si)(2) (2), to provide the stannasiloxane t-Bu(2)Sn[OSi(OSnCl-t-Bu(2))-t-Bu](2) (4, racemate). The reaction of 1 with 1,2-di-tert-butyltetrafluorodisilane, (t-BuF(2)Si)(2) (3), provides the stannasiloxane [t-Bu(F)SiOSn-t-Bu(2)](2)O (5, meso/racemate mixture) and the tetraorganodistannoxane [t-Bu(2)(F)SnOSn(F)-t-Bu(2)](2) (6). Under loss of (1)/(3) mole equiv of 1, the stannasiloxane 5 is transformed into t-Bu(2)Sn[OSi(F)-t-BuSi(F)-t-BuO](2)Sn-t-Bu(2) (7). Its ten-membered ring structure was elucidated by X-ray analysis. In solution, 7 forms the five-membered ring t-Bu(2)Sn[OSi(F)-t-Bu](2) (7a). The dimeric nature of 6 was confirmed by its crystal structure determination. In solution, 6 exhibits a unique valence tautomerism as evidenced by (19)F and (119)Sn NMR spectroscopy.

Synthesis and Solution State Characterization by Gradient-Enhanced 2D Multinuclear NMR Spectroscopy of a Fluorine-Bridged Dimethyltin(IV) Salicylaldoximate Derivative

The reaction of [(Me(2)Sn)(2)(Me(2)SnO)(ONZOH)(HONZO)(ONZO)] (HONZOH = o-HON=CHC(6)H(4)OH, salicylaldoxime) with ammonium fluoride yields a fluorotris(dimethyltin) disalicylaldoximate complex, compound 4, containing one seven-coordinate and two five-coordinate tin atoms, with a fluoride anion bridging the five-coordinate tin atoms. Though 4 can be obtained in a crystalline form, its crystals are unsuitable for X-ray analysis. Its structure has been completely characterized in solution by 1D (1)H, (13)C, (119)Sn, and (19)F NMR spectra and 2D gradient-assisted (1)H-(119)Sn and (1)H-(13)C HMQC and HMBC NMR spectra. In solution, 4 is involved in an equilibrium with several species. It is shown that the Sn(2)-F-Sn(3) moiety of 4 is the reactive site amenable to nucleophilic substitution with weak nucleophiles like water and methanol. The preservation of the splitting of the (1)J((119/117)Sn(3)-(19)F) coupling but not the (1)J((119/117)Sn(2)-(19)F) coupling evidences a reaction intermediate where the entering nucleophile is bound to the Sn(2) tin atom whereas the fluorine is still linked to the Sn(3) atom. Overall, &mgr;(2)-nucleophilic substitutions on compound 4 with hydroxylated nucleophiles should be viewed as addition-elimination reactions.