Di-n-butyltin dichloride (nBu 2 SnCl 2 ) was treated with the potassium salt of cis-1,4-cyclohexanedicarboxylate (cis-1,4-chdcaK 2 ) to give di-n-butyltin cis-1,4-cyclohexanedicarboxylate. In the solid state two supramolecular isomers coexist within the same crystal lattice, the 36-membered macrocyclic tetranuclear complex [{nBu 2 Sn(cis-1,4-chdca)} 4 ] and the analogous polymeric form [{nBu 2 Sn(cis-1,4-chdca)} n ]. In solution, fast (on the NMR time scale) dynamic equilibria were detected. The supramolecular arrangement in the solid state consists of alternating macrocycle and polymer ribbons with

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.

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).

A series of N-containing boronic esters have been prepared by combination of 3-pyridineboronic acid (3-pyba), 4-pyridineboronic acid (4-pyba), and 5-isoquinolineboronic acid (5-iqba) with ethanol, 1,2-ethanediol, and 1,3-propanediol. The resulting self-complementary tectons (SCTs) assembled further through N → B bond formation to give one tetranuclear macrocyclic and four one-dimensional polymeric boron complexes: [(3-py)B(OEt) 2 ] 4 (2), [(3-py)B(OCH 2 CH 2 O)] n (3), [(4-py)B(OEt) 2 ] n (4), [(5-iq)B(OCH 2 CH 2 O)] n (6), and [(5-iq)B(OCH 2 CH 2 CH 2 O)] n (7). In conjunction with the previously reported pentadecanuclear boroxine cage (1) and high-dimensional assemblies derived from pentaerythritol, [(4-py), it was shown that a single class of self-complementary boron-based tectons can give a varied series of finite and infinite supramolecular aggregates. A comparative structural characterization of boron complexes 2−4 and 6−7 by single-crystal X-ray diffraction analysis and quantum-chemical calculations revealed that the corresponding SCTs could have been organized in all cases in the form of tetrameric macrocycles, as it occurred for 2, indicating that intermolecular noncovalent interactions during crystallization probably play a significant role in the output of the assembly process and influence the formation of supramolecular isomers. This observation was supported by a comparison of the molecular geometries of a series of tetranuclear macrocyclic and related linear oligomeric boronic esters derived from 3-pyba, 4-pyba, and 5-iqba, whose structures have been optimized by quantum-chemical calculations at the (B3LYP/cc-pVDZ) level of theory. The calculated structure of [(3-py)B(OEt) 2 ] 4 was in good agreement with the structure obtained experimentally by single-crystal X-ray diffraction analysis. For the cyclo-tetramers derived from 3-pyba and 5-iqba, all common conformers known from calixarene chemistry have been analyzed (cone, 1,3-alternate, 1,2-alternate, and partial cone), showing that the boronic ester group has a significant influence on their relative stability.