New pyridyl-pyrazinyl ketones as ligands for Cu(II), Ag(I), Zn(II) and Cd(II) complexes: Anion-dependent hydrolysis of 2,2′-pyridyl-pyrazinyl ketone and unvaried neat forms of its positional isomers

New isomeric pyridyl-pyrazinyl ketonic ligands 2-pyridinyl-2-pyrazinylmethanone, 3-pyridinyl-2-pyrazinylmethanone and 4-pyridinyl-2-pyrazinylmethanone have been synthesized, and their coordination behavior in a series of group 11 and 12 complexes is probed and discussed.