Chalcogen bonding interactions in telluroether heterocycles [Te(CH2)m]n (n = 1-4; m = 3-7).

The Te…Te secondary bonding interactions (SBI) in solid heterocyclic telluroethers were explored by preparing and structurally characterizing a series of [Te(CH2)m]n (n = 1-4; m = 3-7) species.  The SBIs in 1,7-Te2(CH2)10, 1,8-Te2(CH2)12, 1,5,9-Te3(CH2)9, 1,8,15-Te3(CH2)18, 1,7,13,19-Te4(CH2)20, 1,8,15,22-Te4(CH2)24, and 1,9,17,25-Te4(CH2)28 led to the tubular packing of the molecules, as has been observed previously for related thio- and selenoether rings. The nature of the intermolecular interactions was explored by solid-state PBE0-D3/pob-TZVP calculations involving periodic boundary conditions. The packing of molecules in 1,7,13,19-Te4(CH2)20, 1,8,15,22-Te4(CH2)24, and 1,9,17,25-Te4(CH2)28 form infinite shafts. The electron densities at bond critical points indicate a narrow range of Te…Te bond orders of 0.12-0.14. The formation of the shafts can be rationalized by frontier orbital overlap and charge-transfer.