Mössbauer spectral studies of di- and triorganotin(IV) histidinylleucinates

Some new di- and triorganotin(IV) derivatives of the formulae, R2SnL, where R =Me, Ph, and n-Oct, and L is the dianion of histidinylleucine (H2L abbreviated as H2(His-Leu)) and R′3 SnHL, where R′ = Me and Ph, HL = monoanion of histidinylleucine, have been synthesized. The bonding and coordination behaviour in these derivatives are discussed on the basis of FT-IR and 119Sn Mössbauer spectroscopic studies. The 119Sn Mössbauer studies, together with the IR data suggest that the ligand in R2Sn(His-Leu) acts as dianionic tridentate coordinating through C(O)O − , –NH2 at axial positions and Npeptide at equatorial position while in case of R′3Sn(HHis − Leu) the ligand acts as a monoanionic bidentate coordinating through C(O)O −  and –NH2 giving a distorted trigonal–bipyramidal environment around tin.