| Abstract |
Reaction of K-2[PtCl4] with excess AIkSCN in water gives the alkylthiocyanate complexes trans-[PtCl2-(AlkSCN)(2)] (Alk = Et 1, Pr-n 2; 80-85\%). These species were studied, in particular, by X-ray crystallography. In the solid state, both 1 and 2 exhibit the previously unreported S center dot center dot center dot Cl chalcogen bonding, which consolidates the complexes into networks and leads to layered structures. Theoretical density functional theory calculations and Bader s atoms in molecules analysis demonstrated two types of intermolecular interactions in tetramer (1)(4), viz. the S center dot center dot center dot Cl chalcogen and the H center dot center dot center dot Cl hydrogen bonds. Despite that each particular S center dot center dot center dot Cl or H center dot center dot center dot Cl bonding is weak -with the estimated energy of 1-2 kcal/mol, altogether they play a crucial role in the stabilization of the S2Cl2 fragment in (1)(4), the basis set of superposition error corrected interaction energy being -12.8 kcal/mol per monomer complex molecule. The chalcogen bonding and the rhomboidal structure of the S2Cl2 fragment can be interpreted in terms of electrostatic arguments as a result of the interaction between the belt of negative electrostatic potential around the Cl atoms and the sulfur (Tholes. The natural bond orbital analysis revealed that both LP(S) -> LP*(Pt)/sigma*(Pt-N)/sigma*(Pt-Cl) and LP(Cl) -> sigma o*(S-C) types of hyperconjugative charge transfers are important in the chalcogen bonding. |
