C–H···O_nitrate synthon assisted molecular assembly of hydrogen bonded Ni(II) and Cu(II) complexes

Abstract

Two Schiff base metal complexes [Cu–SPETN·NO₃ (1) and Ni–SPETN·NO₃ (2) [SPETN = 2,2′-[propane,1,3-diylbis(nitrilomethyldyne)pyridyl,phenolate]] with hydrogen bonding groups have been synthesized and characterized by single-crystal X-ray diffraction. In both of the compounds nitrates occupy a crystallographic general position. In 1 the lattice nitrates are on the 2₁ screw axis while in 2 they are at the crystallographic inversion center. C–H···O_nitrate synthons (formed by the nitrate anions and peripheral hydrogen bonding groups of the metal complexes) are non-covalent building blocks in molecular-assembly and packing of the cationic Schiff base metal complexes (M = Ni²⁺, Cu²⁺), resulting in 2-D hydrogen bonded networks. The Cu···Cu non-bonding contact in 1 is 3.268 Å while the Ni–Ni bonding distance in 2 is 3.437 Å.

Keywords:

• Metal-organic complexes
• Crystal engineering
• C–H···O_nitrate synthons
• Molecular-assembly

Acknowledgments

I thank the UGC for Dr D.S. Kothari Fellowship, New Delhi, India. KAS thanks Prof. Gautam R. Desiraju for providing him the laboratory facilities and also for valuable and fruitful discussions. I thank the Rigaku Corporation, Tokyo, for their support through a generous loan of a RigakuMercury375R/M CCD (XtaLAB mini) diffractometer.