Variation of the Molecular Conformation, Shape, and Cavity Size in Dinuclear Metalla-Macrocycles Containing Hetero-Ditopic Dithiocarbamate-Carboxylate Ligands from a Homologous Series of N-Substituted Amino Acids

A homologous series of dithiocarbamate ligands derived from N-substituted amino acids was reacted with different diorganotin dichlorides to give 18 diorganotin complexes. Spectroscopic and mass spectrometric analysis evidenced the formation of assemblies with six-coordinate tin atoms embedded in skewed-trapezoidal bipyramidal coordination environments of composition C2SnS2O2. Single-crystal Xray diffraction analysis for three of the compounds revealed a one-dimensional polymeric structure for the complex with the ligand derived from 5-aminopentanoic acid, which through further intermolecular Sn center dot center dot center dot O interactions generated an overall two-dimensional coordination polymer containing 40-membered hexanuclear tin macrocydes. On the contrary, the ligands derived from 6-aminohexanoic and 8-aminooctanoic acid provided the expected 22- and 26-membered dinuclear macrocyclic structures. Density functional theory calculations for a representative series of macrocyclic complexes of composition [Me(2)SnLx](2) with Lx = -S2CN(Me)-(CH2)(x)-COO- (x = 3-12) enabled a detailed analysis of the variations in the molecular conformation, shape, and cavity size of the macrocydes in dependence of the aliphatic spacer. Because of odd even effects, the difunctional ligands can adopt either a curved or a twisted-pincer shape, while the SnSxO4-x (x = 0-4) moieties can act either as linear or angular tectons with varying connectivity angles.