Crystallographic analysis of different water–halidecluster blends in cationic [(SNS)PdII] pincer complexes

Abstract

X-Ray single-crystal crystallographic analysis of a series of Pd(II) pincer complexes with tridentate ligands comprising a secondary amine sandwiched by two thioether donors of general formula [PdX(RSC₂H₄N(H)C₂H₄SR)]X′·nH₂O [X = X′ = Cl: R = Et, n = 1 (3); R = ^tBu, n = 1.5 (4), R = cychex, n = 2 (5); X = X′ = Br, R = ⁱBu, n = 2 (6); X = Cl, X′ = NO₃, R = ⁱBu, n = 0 (7)] has been carried out at ambient or low temperature. All the cationic complexes with coordinated and uncoordinated halides (Cl or Br) invariably show hydrate aggregation and interaction with the halides to give water–halide cluster blends in the solid lattices. Extensive H-bonding is evident within these water-blends and between these clusters and the cations, giving different forms of hydrates that are dependent on the sulfur substituent and the halide. Complex 3 contains a water–chloride intercalating zigzag chain; 4 shows a wave-like water trimer–chloride; 5 (at 100 K) reveals a water–chloride tape-like structure formed from four disorder water molecules each with half occupancy; 6 (at 100 K) displays a step-like polymer blend formed by aggregation of water tetramers with orthogonal H-bonding interaction with bromides. No lattice hydration is evident when nitrate is the anion (viz. 7).