Shang, Xianmei M.Alegria, ElisabeteGuedes Da Silva, M. Fátima C.Kuznetsov, Maxim L.Li, Qingshan S.Pombeiro, Armando2015-09-082015-09-082012-12SHANG, X. M.; [et al] – Redox-active cytotoxic diorganotin(IV) cycloalkylhydroxamate complexes with different ring sizes: Reduction behaviour and theoretical interpretation. Journal of Inorganic Biochemistry. ISSN: 0162-0134. Vol. 117 (2012), pp. 147-1560162-0134http://hdl.handle.net/10400.21/5121Two series of new diorganotin(IV) cycloalkylhydroxamate complexes with different ring sizes (cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl), formulated as the mononuclear [R2Sn(HL)(2)] (1:2) (a, R=Bu-n and Ph) and the polymeric [R2SnL](n) (1:1) (b, R=Bu-n) compounds, were prepared and fully characterized. Single crystal X-ray diffraction for [(Bu2Sn)-Bu-n{C5H9C(O)NHO}(2)] (3a) discloses the cis geometry and strong intermolecular NH center dot center dot center dot O interactions. The in vitro cytotoxic activities of the complexes were evaluated against HL-60, Bel-7402, BGC-823 and KB human tumour cell lines, the greater activity concerning [(Bu2Sn)-Bu-n(HL)(2)] [HL=C3H5C(O)NHO (1a), C6H11C(O)NHO (4a)] towards BGC-823. The complexes undergo, by cyclic voltammetry and controlled-potential electrolysis, one irreversible overall two-electron cathodic process at a reduction potential that does not appear to correlate with the antitumour activity. The electrochemical behaviour of [R2Sn(C5H9C(O)NHO)(2)] [R=Bu-n (3a), Ph (7a)] was also investigated using density functional theory (DFT) methods, showing that the ultimate complex structure and the mechanism of its formation are R dependent: for the aromatic (R = Ph) complex, the initial reduction step is centred on the phenyl ligands and at the metal, being followed by a second reduction with Sn-O and Sn-C ruptures, whereas for the alkyl (R=Bu-n) complex the first reduction step is centred on one of the hydroxamate ligands and is followed by a second reduction with Sn-O bond cleavages and preservation of the alkyl ligands. In both cases, the final complexes are highly coordinative unsaturated Sn-II species with the cis geometry, features that can be of biological significance.engOrganotin(IV) complexesCycloaliphatic HydroxamateRedox PotentialCytotoxic ActivityElectron-Transfer Induced Bond CleavageMechanism of ReductionSN-119 NMR-spectraAntitumor-activityOrganotin(IV)(N+) complexesCoordination-compoundsRuthenium complexesCrystal-structuresAnticancer drugsAcidIminoacylationOrganonitrilesjournal article10.1016/j.jinorgbio.2012.08.019