Chloride−Chloroform Clusters Exhibiting Weak Hydrogen and Halogen Bondings Are Fully Characterized in the Solid State by X-ray Diffraction

Two (1,3,5-triazapentadiene/ato)PtII complexes, [1][(Cl)2] and [2][(Cl)2], were synthesized by the previously reported platinum-mediated nitrile−amidine coupling. Both complexes crystallize as mixed chloroform−ethanol solvate [1][(Cl)2(CHCl3)7(EtOH)2] and [2][(Cl)2(CHCl3)6(EtOH)2] from the reaction mixture by slow evaporation of the commercial chloroform (containing ca. 1% of EtOH) taken as the solvent, while crystals of [2][(Cl)2(CHCl3)4] were obtained when distilled chloroform was employed. In the crystal structure of [1][(Cl)2(CHCl3)7(EtOH)2], [2][(Cl)2(CHCl3)6(EtOH)2], and [2][(Cl)2(CHCl3)4] solvates, the Cl− ion interacts with [1]2+ or [2]2+ by means of hydrogen bonding and via one hydrogen bridge, thus forming stacked arrays. The negatively charged cluster ions [Cl−(CHCl3)n] (n = 2, 3) are stabilized via C−H···Cl− hydrogen bridges between the Cl− ion and CHCl3 molecules. In [1][(Cl)2(CHCl3)7(EtOH)2], two chloroform clusters dimerize to the [Cl−(CHCl3)3]2 species, where the halogen bonding between one Cl atom of CHCl3 and Cl− anion was detected. The halogen bonding was studied by theoretical methods (B3LYP, MP2), including the bond energy, AIM, and NBO charge transfer analyzes.