Organotin compounds and deoxyribonucleic acid

Abstract

The interaction of organotin(IV) moieties Sn^IVR₂ and Sn^IVR₃(R = Me, Et, Buⁿ, C₈H₁₇ or Ph) with calf thymus deoxyribonucleic acid (DNA) has been studied. The experimental conditions have been determined for the formation of condensates Sn^IVR₂– and Sn^IVR₃–DNA by the reaction of ethanolic organotins [SnR₂Cl₂(EtOH)₂ and SnR₃Cl(EtOH)], as well as aqueous Sn^IVMe₃ species, with aqueous DNA. The nature of the condensates has been investigated by ¹¹⁹Sn Mössbauer spectroscopy. The species SnEt₂(DNA phosphate)₂ and SnR₃(DNA phosphate)(R = Me or Et) have been assumed to occur, where the environment of the tin atoms would be trans octahedral and trigonal bipyramidal respectively. In the reaction with aqueous DNA of SnR₂Cl₂(EtOH)₂ and SnR₃Cl(EtOH)(R = Buⁿ, C₈H₁₇ or Ph), stannoxanes (SnR₂Cl)₂O and hydroxides SnR₃(OH) would form too, being possibly the main reaction products for the moieties Sn^IV(C₈H₁₇)₂, Sn^IV(C₈H₁₇)₃ and Sn^IVPh₃. Possible bonding situations have been advanced for Sn^IVR_n–DNA condensates, involving e.g. two vicinal phosphodiester groups (from the DNA double strand)cis-co-ordinated giving an octahedral geometry, as well as a phosphodiester residue axially binding Sn^IVR₃ to give a trigonal-bipyramidal structure.