Structures and properties of (L-prolinato)copper(II) complexes prepared from different solvents

Abstract

Two amino acid complexes, aquachloro(L-prolinato)copper(II)1 and chloro(methanol)(L-prolinato)copper(II)2, were prepared from aqueous and methanol solutions. Complex 1 crystallized in the monoclinic system, space group P2₁, with a= 9.509(2), b= 5.206(2), c= 8.189(2)Å, β= 109.40(2)°, Z= 2; R 0.030 (R′= 0.043). The structure consists of a one-dimensional polymer chain bridged by a carboxylate group of a L-prolinato (pro) ligand: two carboxylato oxygen atoms in the pro are co-ordinated to different copper atoms, thus forming a carboxylato syn-anti bridge. Each copper atom is surrounded by five atoms, thus forming a square pyramid. Complex 2 also crystallized in the monoclinic system, space group P2₁, with a= 9.038(3), b= 5.980(1), c= 8.567(2)Å, β= 101.62(2)°, Z= 2; R 0.039 (R′= 0.051). Although the structure also consists of a one-dimensional polymer chain bridged by a carboxylate group of a pro ligand, the bridging form is different from that in 1: one carboxylate oxygen atom is co-ordinated to two copper atoms and the other is co-ordinated to one of these copper atoms, thus forming a four-membered chelate ring. Each copper atom in the complex is surrounded by six atoms, thus forming an extremely distorted octahedron. The infrared and elctronic spectra, magnetic moments, and simultaneous thermogravimetric and differential thermal analyses of complexes 1 and 2 are described.