Deprotonated Nitrogen Atoms Research Articles

Cobalt(II), nickel(II) and copper(II) complexes of potentially terdentate N-(2′-picolyl)-2-pyridylacetamide

Abstract Cobalt(II), nickel(II), and copper(II) complexes of N-(2′-picolyl)-2-pyridylacetamide(ppaH) have been studied by means of magnetic moments, and infrared and electronic spectra. The amide group of ppaH is coordinated through its oxygen atom in complexes such as Ni(ppaH)2X2.nH2O (X  Cl, Br or NCS) and [Co(ppaH)2(H2O)2](ClO4)2, where ppaH acts as an N,O-bidentate ligand. The cobalt and nickel complexes are six-coordinate except for [Co(ppaH)Br2].H2O and [H2(ppaH)].[CoCl4], which are tetrahedral. On the other hand, in the copper complexes Cu(ppa)Cl.2H2O and [H3O].[Cu(ppa)SO4] the amide group is coordinated through its deprotonated nitrogen atom and the ligands acts as an N,N,N-terdentate one.

Five-coordinate nickel(II) and copper(II) complexes of quinquedentate acid amides

Five-coordinate nickel(II) and copper(II) complexes of novel linear quinquedentate acid amides have been prepared and their magnetic moments, infrared and electronic spectra were measured. The amide groups of these quinquedentate ligands are coordinated to metals with deprotonated nitrogen atoms. The copper complexes show unique electronic spectra with a high intensity. Nickel forms five-coordinate complexes more easily with deprotonated amide-nitrogen atoms than with azomethine-nitrogen atoms of the ligands having a similar skeleton. These five-coordinate nickel complexes of the acid amides are paramagnetic which have never been reported before.

Intermolecular interactions in the crystal structure of calcium barbital trihydrate

The deprotonated nitrogen atoms in the barbital anions in calcium barbital trihydrate are involved either in co-ordination to the calcium cations or as acceptors in hydrogen bonds, whereas the non-deprotonated ones are involved as donors to form isolated hydrogen-bonded barbital dimers.