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 X-ray 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···O interactions generated an overall two-dimensional coordination polymer containing 40-membered hexanuclear tin macrocycles. 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 [Me2SnLx]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 macrocycles 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.

N-containing boronic esters as self-complementary building blocks for the assembly of 2D and 3D molecular networks.

The combination of two heteroaromatic boronic acids with pentaerythritol gave self-complementary tectons which were suitable for the generation of 2D and 3D molecular networks.

Macrocyclic diorganotin complexes of gamma-amino acid dithiocarbamates as hosts for ion-pair recognition.

The dimethyl-, di-n-butyl-, and diphenyltin(IV) dithiocarbamate (dtc) complexes [{R2Sn(L-dtc)}x] 1-7 (1, L = L1, R = Me; 2, L = L1, R = n-Bu; 3, L = L2, R = Me, x = infinity; 4, L = L2, R = n-Bu; 5, L = L3, R = Me, x = 2; 6, L = L3, R = n-Bu, x = 2; 7, L = L3, R = Ph, x = 2) have been prepared from a series of secondary amino acid (AA) homologues as starting materials: N-benzylglycine (alpha-AA derivative = L1), N-benzyl-3-aminopropionic acid (beta-AA derivative = L2), and N-benzyl-4-aminobutyric acid (gamma-AA derivative = L3). The resulting compounds have been characterized by elemental analysis, mass spectrometry, IR and NMR ((1)H, (13)C, and (119)Sn) spectroscopy, thermogravimetric analysis, and X-ray crystallography, showing that in all complexes both functional groups of the heteroleptic ligands are coordinated to the tin atoms. By X-ray diffraction analysis, it could be shown that [{Me2Sn(L2-dtc)}x] (3) is polymeric in the solid state, while the complexes derived from L3 (5-7) have dinuclear 18-membered macrocyclic structures of the composition [{R2Sn(L3-dtc)}2]. For the remaining compounds, it could not be established with certainty whether the structures are macrocyclic or polymeric. A theoretical investigation at the B3LYP/SBKJC(d,p) level of theory indicated that the alpha-AA-dtc complexes might have trinuclear macrocyclic structures. The macrocyclic complexes 5-7 have a double-calix-shaped conformation with two cavities large enough for the inclusion of aliphatic and aromatic guest molecules. They are self-complementary for the formation of supramolecuar synthons that give rise to 1D molecular arrangements in the solid state. Preliminary recognition experiments with tetrabutylammonium acetate have shown that the [{R2Sn(L3-dtc)}2] macrocycles 6 and 7 might interact simultaneously with anions (AcO(-)), which coordinate to the tin atoms, and organic cations (TBA(+)), which accommodate within the hydrophobic cavity (ion-pair recognition).

24- and 26-membered macrocyclic diorganotin(IV) bis-dithiocarbamate complexes with N,N'-disubstituted 1,3- and 1,4-bis(aminomethyl)benzene and 1,1'-bis(aminomethyl)ferrocene as spacer groups.

The potassium bis-dithiocarbamate (bis-dtc) salts of 1,3-bis(benzylaminomethyl)benzene (1,3-Bn-ambdtc), 1,3-bis(iso-butylaminomethyl)benzene (1,3-(i)Bu-ambdtc), 1,4-bis(benzylaminomethyl)benzene (1,4-Bn-ambdtc), and 1,4-bis(iso-butylaminomethyl)benzene (1,4-(i)Bu-ambdtc) were reacted with three different diorganotin dichlorides (R2SnCl2 with R = Me, (n)Bu, and Ph) in 1:1 stoichiometric ratios to give the corresponding diorganotin bis-dithiocarbamates. Additionally, the dimethyltin bis-dithiocarbamate of 1,1'-bis(benzylaminomethyl)ferrocene (1,1'-Bn-amfdtc) was prepared. The resulting complexes have been characterized as far as possible by elemental analysis, FAB(+) mass spectrometry, IR and NMR ((1)H, (13)C, and (119)Sn) spectroscopy, and single-crystal X-ray diffraction, showing that the tin complexes are dinuclear 24- and 26-membered macrocyclic species of composition [{R2Sn(bis-dtc)}2]. As shown by (119)Sn NMR spectroscopy, the tin centers are hexa-coordinated in all cases; however, two different coordination environments are possible, as detected by single-crystal X-ray diffraction. In the dimethyltin derivatives of 1,3-Bn-ambdtc, 1,3-(i)Bu-ambdtc, 1,4-Bn-ambdtc, and 1,1'-Bn-amfdtc and the di-n-butyltin derivative of 1,3-(i)Bu-ambdtc, the metal atoms are embedded in skewed-trapezoidal-bipyramidal coordination polyhedra with asymmetrically coordinating trans-oriented dtc groups. In contrast, in the diphenyltin derivative 1,3-(i)Bu-ambdtc, the metal centers have distorted octahedral coordination with symmetrically coordinating cis-oriented dtc functions. Thus, for the complexes derived from 1,3-Bn/(i)Bu-ambdtc, two different macrocyclic structures were observed. In the dimethyl- and di-n-butyltin derivatives, the bridging bis-dtc ligands adopt U-shaped conformations, while in the case of the diphenyltin derivative, the conformation is L-shaped. Furthermore, two different macrocyclic ring conformations can occur, which differ in the spatial orientation of the substituents attached to the nitrogen atoms (Bn or (i)Bu). The dimethyltin derivatives of 1,4-Bn-ambdtc and 1,1'-Bn-amfdtc have cavities, in which aromatic rings are accommodated in the solid state.