A robust conglomerate structure type in salts of cationic organopalladium complexes and non-coordinating anions

Abstract

Ionic compounds derived from square planar cations of the type [Pd(C₆H₄CHMeNH₂)(tmeda)]⁺ (tmeda = 1,1,2,2-tetramethylethylenediamine) and the non-coordinating anions BF₄^–, PF₆^– and CF₃SO₃^– have been prepared by cyclopalladation of (aryl-substituted) primary amines and subsequent reaction with the chelating tmeda ligand. Six compounds among the tetrafluoroborates and hexafluorophosphates of unsubstituted and methyl, fluoro or chloro substituted cyclopalladated amines are isotypic: They all show conglomerate behaviour, crystallizing in the same space group with similar lattice parameters and closely related packing. Only one moderately strong hydrogen bond per formula unit between an amine H and a counteranion is formed. The stability range of this remarkably robust structure type has been explored by variation of the anion and substitution on the aryl ring of the primary amine. For three related palladium complexes which do not show conglomerate crystallization, the structures of their enantiopure and racemic crystals are reported for comparison.