Hydrolysis, polymerisation, and structure of dimethyltin (IV) in aqueous solution. Molecular structure of the polymer [(SnMe2)2(OH)3]ClO4

CHEMICAL & PHARMACEUTICAL BULLETIN

2001

Among organotins, dialkyl derivatives exhibit greater antitumour activity than the corresponding mono-, tri-, and tetraalkyl derivatives.2) The activity of the tri-or tetra-alkyl derivatives may be explained by dealkylation in vivo which yields the corresponding active dialkyl derivatives. If one ranks specific alkyl organotins in terms of antitumour activity of the parent compounds, the diethyl and diphenyl derivatives have the highest activity in vivo provided that one takes no cognizance of their toxicity. 3)Accepting the hypothesis that R 2 Sn 2ϩ are the usual active species for the antitumour action of organotins, 4) a good antitumour agent should be easily dissociable following administration to animals. This requires weak bonds between tin and the donor atom of the coordinated organic compounds which are readily hydrolysable. If the compound is hydrolytically unstable, the R 2 Sn moiety will be released too soon, and if it is too stable, it may be released too slowly and consequently lower activity will be observed. Such a mechanism also adds weight to the proposition for the R 2 SnX 2 L 2 adducts, where it was shown that relatively long Sn-N bonds were a requirement for activity, and that predissociation of the ligand L 2 may be an important feature of the mode of action of this particular class of compounds. Therefore, there is a relationship between the stability of the organotin compounds and their antitumour activity.In continuation of our studies on organotin(IV) complexes, 5-11) the present paper aims to study the diphenyltin-(IV) complex formation equilibria with some selected bioligands, with the hope that such types of coordinating ligands might possess favorable properties, possibly as carriers in body fluids. ExperimentalMaterials and Reagents Diphenyltin(IV) dichloride (DPT) was obtained from Merck Chem. Co. The ligands used were glycine, proline, methionine, serine, histidine, histamine, ornithine, lysine, aspartic acid, glutamic acid, mercaptoethylamine, mercaptopropionic acid, penicillamine, glutathione, cyclobutane dicarboxylic acid (CBDCA), oxalic acid, malonic acid, succinic acid, adipic acid, fumaric acid, glycylglycine, glycylalanine, glycylleucine, glycylmethionine, glutamine and aspargine. These were supplied by Fluka Chem. Co. The DPT was converted to the perchlorate form by suspension in dioxane, addition of 1.98 eq of AgClO 4 and stirring over night. The precipitate (AgCl) was filtered and the resulting final solution was diluted to a 75% dioxane-water solution. The concentration of DPT was checked potentiometrically. Solutions of histidine, ornithine, lysine were prepared in the protonated form by dissolving in equimolar HNO 3 solution. Carbonate free sodium hydroxide stock solutions were prepared by diluting the contents of British Druy House (BDH) concentrated volumetric solutions vials. These solutions were systematically checked by titration against potassium hydrogen phthalate.Procedure and Measuring Techniques Potentiometric titrations were performed using a Metrohm 686 ti...

supporting

confidence: 82%

“…It is found that pK a values of the ligands in 75% dioxane-water solutions are higher than those reported in water. This may 5 and M 4 (OH) 6 reported for dimethyltin-(IV) [18][19][20][21] were rejected. This may be due to the very poor solubility of hydrolysed diphenyltin(IV) species.…”

Section: Resultsmentioning

confidence: 99%

Interaction of Diphenyltin(IV) Dichloride with Some Selected Bioligands.

Mohamed

CHEMICAL & PHARMACEUTICAL BULLETIN

2001

“…The hydrolysis of the dimethyltin(IV) cation in aqueous solution was studied by several research groups (Arena et al, 1995;Natsume et al, 1994;Buzás et al, 1998;De Stefano et al, 1996;Foti et al, 1999). The potentiometric data were fitted considering the formation of the species 10-1, 10-2, 10-3, 10-4 and 20-2 (Table 1).…”

Section: Resultsmentioning

confidence: 99%

“…Earlier structural studies using X-ray, neutron and electron diffraction (Ho and Zuckerman, 1973) and Moessbareer spectroscopy (Bancroft et al, 1976) revealed that the trimethyltin(IV) complexes have a triagonal bipyramidal configuration with three methyl groups in equatorial and two water molecules in axial positions. Complex formation would then involve ligand substitution of water molecule and binding occurs to ionised hydroxyl group of dehydroacetic acid (Natsume et al, 1994).…”

Section: Complex Formation Equilibria Of Alkyltin (Iv)mentioning

confidence: 99%

Interaction of dimethyltin(IV) and trimethyltin(IV) with dehydroacetic acid

Alousi

Shehata

Chemical Speciation & Bioavailability

et al. 2009

“…The hydrolysis of dimethyltin(IV) cation in aqueous solution was studied by several research groups (15)(16)(17)(18) . The potentiometric data were fitted considering the formation of the species 10-1, 10-2, 10-3, 10-4, 20-3 and 20-4, Table 2.…”

Section: Hydrolysis Of Dimethyltin(iv)mentioning

confidence: 99%

Interaction of Dimethyltin(iv) Dichloride With, Bidentate Amine: Synthesis and Equilibrium Studies.

Al-Azhar Bulletin of Science

Tollma

Shehat

et al. 2007

The interaction of dimethyltin(IV) with some selected aliphatic and aromatic diamines was described. A series of diamine complexes were synthesized and characterized by elemental analysis. The stoichiometry and stability constants for the complexes are estimated at 25°C and 0.lM ionic strength. The concentration distribution diagrams of the complexes were evaluated. The effect of pKa of the diamine on the stability constant of the complex was elucidated.