Search

An exhaustive structural survey was analyzed in combination with new structural reports on pnictogen···π interactions. The Cambridge Structural Database was searched for examples of pnictogen atoms (As, Sb, and Bi) that lie within the sum of their van der Waals radii with an arene ring. The results were analyzed, and it was concluded that the interaction distance is shorter for the heavier pnictogens due to the increasingly diffuse nature of the lone pair of electrons on the atom. A weak correlation between the distance and the angle of the interaction was found, implying that the interaction is partially covalent in nature but is primarily a dispersion interaction. These arene···π interactions can be used as driving forces for supramolecular assembly, and the crystal structures of two new arsenic-containing assemblies are presented. The combined analysis of these structures and the structural survey suggest that our supramolecular design strategy can be fine-tuned to take advantage of the pnictogen···π i...

The synthesis and crystal structures of two new macrocyclic compounds, As2(L2,5)2Cl2 and As2(L2,3)2Cl2, are described, where L2,3 and L2,5 are dithiolate ligands. For each compound, several diastereomeric isomers are possible (anti-“aligned”, syn-“aligned”, anti-“unaligned”, syn-“unaligned”), as shown by density functional theory (DFT) calculations, but only one is crystallized out of solution. For As2(L2,5)2Cl2, only the anti-aligned isomer crystallizes, as expected based on steric arguments and backed up by DFT calculations. Surprisingly, for As2(L2,3)2Cl2, an anti isomer crystallizes in which one As−Cl unit has folded into the macrocyclic cavity. While this goes against steric arguments and DFT calculations, this conformation best fills the space within the cavity, avoiding the entropic cost of a large void.

Treatment of 1,4-bis(2-mercaptoethyl)benzene (1) or 1,4-bis(2-bromoethyl)benzene (2) with excess SbCl3 affords new one-dimensional and two-dimensional supramolecular coordination networks. Compound 1·2SbCl3 is stabilized solely by Sb···Cl, Sb-π, and Sb···S secondary bonding interactions (SBIs), providing an unusual example of Sb(III) and a thiol interacting through an SBI rather than a strong antimony thiolate bond. 2·2SbCl3 is stabilized by Sb···Cl, Sb···Br, and Sb-π SBIs. Both compounds have higher melting points than that of SbCl3. The crystal structures of 1·2SbCl3 and 2·2SbCl3 have been determined by single crystal X-ray diffraction methods.

The syntheses and X-ray crystal structures of six new self-assembled supramolecular As and Sb-containing cryptands are described. Analysis in the context of previously reported As(2)L(3) and Sb(2)L(3) cryptands reveals that small differences in ligand geometries result in significant differences in the helicity of the complexes and the stereochemistry of the metal coordination within the assembled complexes. Additionally, a new synthetic route is described which involves exposure of reactants to vacuum to help facilitate self-assembly.