Synthesis, spectroscopic characterization, DFT calculations, and dynamic behavior of mononuclear macrocyclic diorganotin(IV) bis-dithiocarbamate complexes

Nine mononuclear diorganotin(IV) dithiocarbamate complexes 1-9 with 19-, 20- and 21-membered macrocyclic structures were synthesized from dimethyl, di-n-butyl, and diphenyltin(IV) dichloride and three bis-dithiocarbamate ligands derived from secondary bis-amines having aromatic spacer groups. All compounds were characterized by elemental analysis, mass spectrometry, and spectroscopic methods (IR and ¹H, ¹³C, and ¹¹⁹Sn NMR). Additionally, quantum chemical DFT calculations were performed for the dimethyltin(IV) derivatives in order to model the molecular structures. For one compound series the NMR spectra showed a concentration-dependent behavior in solution, which was analyzed in detail and permitted to postulate the existence of an equilibrium with the corresponding [2+2] macrocycles.