Solid-state molecular structures of Se(IV) and Te(IV) dihalides X2Se(CH3)(C6F5) and the gas-phase structure of Se(CH3)(C6F5)

In a systematic study the Se(IV) and Te(IV) dihalides F2E(CH3)(C6F5), Cl2E(CH3)(C6F5) and Br2E(CH3)(C6F5) (E = Se, Te) have been synthesized and their crystal and molecular structures been investigated by X-ray diffraction and computational methods. The solid-state structures of all compounds show significant correlations between the lengths of the E-C1 bond and the intermolecular E & BULL;& BULL;& BULL;X (X = F, Cl and Br) contacts, indicating the presence of sigma-hole interactions. For comparison, the crystal and gas phase (electron diffraction) structures of Se(CH3)(C6F5) are presented as well. They show very similar structural parameters in both phases. The structures of the single molecules X2E(CH3)(C6F5) have been analyzed by quantum-chemical methods in terms of their surface potentials. They show significant similarities of their molecular electrostatic-potential topologies (V (s,max)). The magnitude of V (s,max) correlates with the aggregation pattern.