X-ray crystallographic, spectroscopic, and electrochemical properties of Group 12 metal-chlorides of di-2-pyridyl ketone acetic acid hydrazone (dpkaah). Issue 15 (3rd August 2018) - Bakir, Mohammed
Abstract: Di-2-pyridyl ketone acetic acid hydrazone hydrate, dpkaah.0.5H2 O (1 ), prepared from the acid catalyzed condensation of di-2-pyridyl ketone (dpk) with acetic acid hydrazide in refluxing ethanol, undergoes facile coordination to Group 12 metal-chlorides in CH3 CN to form [MCl2 (κ 3 -N, N, O-dpkaah)] {M=Zn (3 ), Cd (4 ) or Hg(5 )}. X-ray structural analysis on single crystals of dpkaah (2 ) and3 –5 confirmed their identities and revealed pseudo-coordination of the carbonyl group (C=O). Infrared measurements confirmed the pseudo-coordination of the carbonyl group to MCl2 . The geometries of3 –5 vary, while5 adopts a square pyramidal geometry, 4 has a structure halfway between square pyramidal and trigonal bipyramidal and3 is less distorted from square pyramidal than3 . The extended structures of3 –5 exposed extensive networks of non-covalent interactions, and in the case of4 chloride bridges of the type Cd(μ-Cl)2 Cd were observed. Spectroscopic measurements in different solvents and variable temperature studies confirmed the stability of the keto form of1 and3 –5 . Spectrophotometric titrations of protophilic solutions (dmf or dmso) of1 with MCl2 revealed facile coordination of MCl2 to1 and disclosed low concentrations of MCl2 can be detected and determined using protophilic solutions of1 . Electrochemical measurements on dmf solutions divulged electrochemical decomposition of uncoordinated1, the facile coordination of1 to MCl2, and the stability of3 –5 decreases as the size of the metal ion increases. Abstract :