Unusual chalcogen-boron ring compounds: the gas-phase structures of 1,4-B4S2(NMe2)4 and related molecules.

The structure of 1,4-B4S2(NMe2)4 has been determined by gas-phase electron diffraction and quantum chemical calculations and is compared with the known solid-state structure. While these structures are similar, with a twisted ring geometry [the dihedral angle S-B-B-S from electron diffraction is 75.4(16) degrees], they are strikingly different to the solid-state structure of 1,4-B4O2(OH)4, which is planar.