Chalcogen-Bonding Interactions in Telluroether Heterocycles [Te(CH(2) )(m) ](n) (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(2) )(m) ](n) (n=1-4; m=3-7) species. The SBIs in 1,7-Te(2) (CH(2) )(10) , 1,8-Te(2) (CH(2) )(12) , 1,5,9-Te(3) (CH(2) )(9) , 1,8,15-Te(3) (CH(2) )(18) , 1,7,13,19-Te(4) (CH(2) )(20) , 1,8,15,22-Te(4) (CH(2) )(24) and 1,9,17,25-Te(4) (CH(2) )(28) 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(4) (CH(2) )(20) , 1,8,15,22-Te(4) (CH(2) )(24) and 1,9,17,25-Te(4) (CH(2) )(28) 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.