Orthogonal non-covalent binding forces in solid state supramolecular herringbone-shaped “interlocked dimers”. Pseudopolymorphism in [(ppy)Pd(μ-pz)]2 (ppy = 2-(2-pyridyl)phenyl, pz = pyrazol-1-yl) complex

Abstract

The crystal structures of [(ppy)Pd(μ-pz)]₂ (ppy = 2-(2-pyridyl)phenyl, pz = pyrazol-1-yl) (1) and two different solvatomorphs of it, [(ppy)Pd(μ-pz)]₂·½CH₂Cl₂ (2) and [(ppy)Pd(μ-pz)]₂·½CHCl₃ (3) have been elucidated by powder (1 and 2) and single crystal (3) X-ray diffraction. In all of them two molecules fit together following a very similar pattern forming a “dimer”. All neutral dinuclear square-planar complexes having μ-pz or related bridges and planar aromatic ligands completing the coordination spheres found in the CSD show a similar arrangement to those observed in compounds 1–3, consisting of “interlocked dimers” following a herringbone-like pattern. A DFT study reveals the simultaneous action of π,π- and T-stacking interactions occurring as two sets of orthogonally oriented binding forces, as well as anagostic bonds overlapped with the latter.