Copper(II)-assisted hydrolysis of 2,4,6-tris(2-pyridyl)-1,3,5-triazine. Part 1. Crystal structures of [bis(2-pyridylcarbonyl)amido](2-pyridylformamide)-copper(II) perchlorate monohydrate and [bis(2-pyridylcarbonyl)amido]-copper(II) perchlorate

Abstract

2,4,6-Tris(2-pyridyl)-1,3,5-triazine (tptz) undergoes hydrolysis in the presence of copper(II) nitrate yielding mainly [bis(2-pyridylcarbonyl)amido]copper(II) and free 2-picolinamide (2-pyridylformamide, NC₅H₄CONH₂). Two new compounds of formulae [Cu{(NC₅H₄CO)₂N}(NC₅H₄CONH₂)]ClO₄·H₂O (1) and [Cu{(NC₅H₄CO)₂}]ClO₄(2), where (NC₅H₄CO)₂N^– is the bis(2-pyridylcarbonyl)amido anion, have been obtained from aqueous solutions of tptz and copper(II) perchlorate. Crystals of (1) are monoclinic with a= 8.443(4), b= 27.145(12), c= 9.781 (5)Å, β= 100.40(6)°, space group P2₁/n, and Z= 4. Crystals of (2) are tetragonal with a=b= 8.071 (5), c= 21.291 (8)Å, space group P4₁, and Z= 4. The structure of (1) is made up of [Cu{(NC₅H₄CO)₂N}(NC₅H₄CONH₂)]⁺ mononuclear cations plus semi-co-ordinated perchlorate anions and water of crystallization. The copper(II) ion is in a distorted octahedral environment: the three nitrogen atoms of the (NC₅H₄CO)₂N^– ligand and the pyridinic one of the 2-picolinamide form a distorted square plane around the copper while the axial positions are occupied by the oxygen atom of the picolinamide and by an oxygen atom of the perchlorate anion. The structure of (2) consists of bis(2-pyridylcarbonyl)amido-bridged copper(II) one-dimensional chains and non-co-ordinated perchlorate anions. The copper(II) ion has a co-ordination geometry which approximates to trigonal bipyramidal: the apices and one of the equatorial positions of the bipyramid are occupied by the two nitrogen atoms of the pyridine rings and the imine-nitrogen atom respectively, whereas the two other equatorial positions are filled by the two carbonyl-oxygen atoms of another bis(2-pyridylcarbonyl)amido ligand. The structure of (1) allows the nature of the two main products of the copper(II)-assisted hydrolysis of tptz to be established and the structure of (2) shows the ability of the bis(2-pyridylcarbonyl)amido anion to act as a bridging ligand with transition metal ions.