Chalcogen-Bonding Interactions in Telluroether Heterocycles [Te(CH2)m]n(n=1-4;m=3-7)

The Te center dot center dot center dot Te secondary bonding interactions (SBIs) in solid cyclic 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-Te-2(CH2)(10), 1,8-Te-2(CH2)(12), 1,5,9-Te-3(CH2)(9), 1,8,15-Te-3(CH2)(18), 1,7,13,19-Te-4(CH2)(20), 1,8,15,22-Te-4(CH2)(24) and 1,9,17,25-Te-4(CH2)(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 PBE0D3/pob-TZVP calculations involving periodic boundary conditions. The molecular packing in 1,7,13,19-Te-4(CH2)(20), 1,8,15,22-Te-4(CH2)(24) and 1,9,17,25-Te-4(CH2)(28) forms infinite shafts. The electron densities at bond critical points indicate a narrow range of Te center dot center dot center dot Te bond orders of 0.12-0.14. The formation of the shafts can be rationalized by frontier orbital overlap and charge transfer.