A family of heterotetrameric clusters of chloride species and halomethanes held by two halogen and two hydrogen bonds

Abstract

Two previously reported 1,3,5,7,9-pentaazanona-1,3,6,8-tetraenate (PANT) chloride platinum(II) complexes [PtCl{HNC(R)NCN[C(Ph)C(Ph)]CNC(R)NH}] (R = tBu 1, Ph 2) form solvates with halomethanes 1·1¼CH2Cl2, 1·1⅖CH2Br2, and 2·CHCl3. All these species feature novel complex-solvent heterotetrameric clusters, where the structural units are linked simultaneously by two C–X⋯Cl–Pt (X = Cl, Br) halogen and two C–H⋯Cl–Pt hydrogen bonds. The geometric parameters of these weak interactions were determined using single-crystal XRD, and the natures of the XBs and HBs in the clusters were studied for the isolated model systems (1)2·(CH2Cl2)2, (1)2·(CH2Br2)2, and (2)2·(CHCl3)2 using DFT calculations and Bader's AIM analysis. The evaluated energies of the weak interactions are in the range 0.9–3.0 kcal mol−1. The XBs and HBs in the reported clusters are cooperative. In the cases of (1)2·(CH2Cl2)2 and (1)2·(CH2Br2)2, the contribution of the HBs to the stabilization of the system is dominant, whereas for (2)2·(CHCl3)2 contributions of both types of the non-covalent interactions are almost the same. Crystal packing and other forces such as, e.g. dipole–dipole interactions, also affect the formation of the clusters.