Lattice Water-Induced Helical Stacking of Tartrate-Bridged Dinuclear Palladium(II) Complexes: The Role of Hydrogen Bonding

摘要

Hydrous crystals of [{PdII(bpy)}2(μ-x-tart)]· nH_2O (bpy: 2,2′-bipyridine; tartH_2~(2?): tartrate; 1a: x = L, n = 6; 2a: x = D, n = 6; 3a: x = DL, n = 4; 4a: x = meso, n = 4) and anhydrous crystals of [{Pd~(II)(bpy)}2(μ-L-tart)] (1b) were isolated from aqueous and MeOH solutions, respectively. Xray crystallography revealed the stacked structures of clamshell- like dinuclear units in 1a?3a and 1b, where intramolecular metal?metal and π?π stacking interactions were observed. Right- and left-handed helically stacked columns were formed in the 1a and 2a crystals, respectively. The significant role of hydrogen bonding among lattice water molecules and tartrate is suggested because 1b exhibited a zigzag arrangement only through intermolecular metal?metal interactions. In 3a, L- and D-tart units stacked alternately in a zigzag arrangement with intermolecular π?π interactions. In 4a, dimeric aggregates of the twisted dinuclear units further formed a 2D sheet architecture.