Crystal Packing in Planar Platinum(II) and Palladium(II) Complexes. Hydrogen-Bond-Mediated Supramolecular Assembly of Ten Wedge-Shaped Molecules into a Cyclic Array

The molecular packing arrangements for the unsolvated compounds, PtCl2(ATQ-CH2NH2) (1a) and PdCl2(ATQ-CH2NH2) (2) (ATQ = azatriquinane), and two solvates of the platinum complex, 6{PtCl2(ATQ-CH2NH2)}·2(CH3CN) (1b) and 3{PtCl2(ATQ-CH2NH2)}·2(CH2Cl2) (1c), are reported. These planar, d8 complexes have a wedgelike shape due to the presence of the bulky azatriquinane unit coordinated directly to the metal. All of the crystals exhibit hydrogen bonding between the N−H groups of one molecule and the chloride ligands on another. Despite the similar sizes and shapes of the complexes, the unsolvated compounds, PtCl2(ATQ-CH2NH2) (1a) and PdCl2(ATQ-CH2NH2) (2), pack in entirely different fashions, with metallophilic interactions between pairs of cofacial complexes in the palladium complex. The platinum complex lacks the metallophillic interactions. The structure of 6{PtCl2(ATQ-CH2NH2)}·2(CH3CN) (1b) is noteworthy for two features. First, these crystals contain an ordered cyclic assembly of 10 molecules of the complex with all the Pt−Cl groups directed toward the inside of the ring. The formation of this supramolecular macrocyclic array is facilitated by extensive hydrogen bonding between the NH groups of one molecule and the chloride ligands of another. Second, these crystals also contain a poorly organized region where one PtCl2(ATQ-CH2NH2) molecule is disordered over several orientations. 3{PtCl2(ATQ-CH2NH2)}·2(CH2Cl2) (1c) crystallizes with three molecules of the platinum complex in a crescent-shaped array that shows some similarity with the cyclic structure found in 6{PtCl2(ATQ-CH2NH2)}·2(CH3CN) (1b).