Copper(II) complexes with acetone picolinoyl hydrazones: Crystallographic insight into metalloligand formation

Complexes with free donor atoms, termed metalloligands, are important building blocks in the stepwise approach towards mixed-metal organic frameworks. In this work, the possibility of a metalloligand formation from nicotinic or isonicotinic Acid hydrazides and copper(II) centers, is assessed. Syntheses, X-ray crystal structures and spectroscopic properties of two new copper(II) compounds with acetone 3- and 4-picolinoyl hydrazones are reported. The structural studies reveal the formation of a mononuclear cationic metalloligand in [Cu(Hisn)(2)](NO3)(2) (1) with a zwitterionic acetone isonicotinoyl hydrazone (Hisn), as well as a neutral, layered (2D) coordination polymer, [Cu(mu-nic)(2)](n) (2), with a deprotonated acetone nicotinoyl hydrazone (Hnic). Heteroatom position in the hydrazide precursor and copper salt acidity influence the formation of pure products. (C) 2015 Elsevier B.V. All rights reserved.