Hydrogen bonding patterns in pyrazole Pt(II- and IV) chloride complexes

The solid-state packing arrays of the platinum(II) trans- and cis-[PtCl2(PzH)2] (1 and 2) and platinum(IV) trans- and cis-[PtCl4(PzH)2] (3 and 4) complexes have been examined and the occurrence of N–H ⋯ Cl hydrogen-bonding associations in those structures has been discussed. Although different packing motifs are observed, in all cases molecules are interacting mostly via NH ⋯ Cl and CH ⋯ Cl associations. The square planar 1 and 2 form stacked arrays of PtCl2(PzH)2, which are supported by NH ⋯ Cl and CH ⋯ Cl hydrogen bonding. The isomeric structure of the complexes and orientation of the PzH rings determine NH ⋯ Cl bonding mode (intermolecular or intramolecular) and also the extent of the platinum–platinum interaction. The synthetic procedures for the preparation of 1–4 along with elemental and X-ray analyses, TG/DTA, FAB+-MS, IR, and 1H and 13C{1H} NMR data are also given in this article.