The Effect of Steric Hindrance on the Association of Telluradiazoles through Te−N Secondary Bonding Interactions

DFT calculations were used to compare the magnitude of steric repulsion to the strength of secondary bonding
interactions (SBIs) in the (Te−N)2 supramolecular synthon to explain or predict the supramolecular structures assembled by two
derivatives of the 1,2,5-telluradiazole ring:  benzo-2,1,3-telluradiazole (4c) and 3,6-dibromobenzo-2,1,3-telluradiazole (5). The
crystallographically determined structures were consistent with the computational predictions. In sharp contrast with the previously
known structures of its sulfur and selenium analogues, 4c forms infinite ribbon chains in the solid state with 2.682(7)−2.720(7) Å
Te−N SBIs. Steric hindrance in 5 restricted the supramolecular association to form discrete dimers with 2.697(8) Å Te−N SBIs.
In addition to discrete dimers, the dibromo derivative crystallizes as solvated dimers in 5·DMSO with 2.834(5) Å Te−O SBIs.
Other weaker SBIs were identified in the crystal lattices and were assessed by the computational method.