Synthesis and spectroscopic characterization of dicyclohexyltin derivatives of dipeptides, and in vitro effects against MDA‐MB 231 breast cancer cells: Crystal structures of dicyclohexyltin glycylglycinate and glycylalaninate

Dicyclohexyltin derivatives Cy 2 SnL (Cy = cyclohexyl) of the dipeptides H 2 L, glycylglycine, glycylalanine, alanylglycine, glycylvaline, glycylmethionine, glycylphenylalanine and glycyltyrosine, have been obtained by neutralization of Cy 2 SnO and H 2 L. The crystal structures of Cy 2 SnL (L = glycylglycinate, glycylalaninate) have been determined by single X‐ray diffraction. Tin in each case has a distorted trigonal bipyramidal environment with the dipeptide acting as a tridentate NNO ‐ligand. From IR‐data, and in some cases from 119 Sn Mössbauer and 119 Sn NMR data, analogous molecular structures are inferred for the other compounds Cy 2 SnL. Spectroscopic data indicate that the solid‐state structures are retained in organic solvents. In vitro tests showed Cy 2 SnL (H 2 L = glycylglycine, glycylalanine, alanylglycine, glycylphenylalanine, glycyltyrosine) to exhibit high cytotoxicity against MDA/MB 231 breast cancer cells, while Me 2 SnL (L = glycylalaninate, glycyltyrosinate, glycyltryptophanate), and R 2 Snglycylglycinate (Rn‐Bu, Ph) proved to be much less active.