Chalcogen-Bonding Interactions in Telluroether Heterocycles [Te(CH ) ] (n=1-4; m=3-7).

The Te⋅⋅⋅Te secondary bonding interactions (SBIs) in solid cyclic telluroethers were explored by preparing and structurally characterizing a series of [Te(CH ) ] (n=1-4; m=3-7) species. The SBIs in 1,7-Te (CH ) , 1,8-Te (CH ) , 1,5,9-Te (CH ) , 1,8,15-Te (CH ) , 1,7,13,19-Te (CH ) , 1,8,15,22-Te (CH ) and 1,9,17,25-Te (CH ) lead to 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 molecular packing in 1,7,13,19-Te (CH ) , 1,8,15,22-Te (CH ) and 1,9,17,25-Te (CH ) forms 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.