Copper(II) halide complexes of aminopyridines: Syntheses, structures and magnetic properties of [(5CAP)2CuX2] and [(5BAP)nCuX2] (X = Cl, Br). Issue 16 (17th September 2018) - Farris, Penelope C.
Abstract: Reaction of 2-amino-5-halopyridine molecules with Cu(II) halides in the solid state via mechanochemical techniques produced four coordination complexes, (5BAP)2 CuBr2 (2a ), (5BAP)2 CuCl2 (3 ), (5CAP)2 CuCl2 (4 ), (5CAP)2 CuBr2 (5 ) [5BAP = 2-amino-5-bromopyridine; 5CAP = 2-amino-5-chloropyridine]. In all compounds, the 5BAP or 5CAP ligands are coordinated to the Cu(II) ion through the pyridine N atom along with two halide ions. Compounds2 and3 crystallized in the P-1 and P21 / c space groups, respectively. Temperature dependent magnetic susceptibility data for2 were fit to the antiferromagnetic rectangle model ( J = –4.5(2) K; α = 0.89(17)), while the data for3 were fit to the uniform chain model ( J = –4.20(6) K), indicating a significant difference in the interchain interactions. Both4 and5 crystallize with the 5CAP ligands in the syn-conformation in the space groups I2/ a and P21/ n, respectively. Compound4 formed the expected dimeric structure via bridging chloride ions and the magnetic data were successfully fit to the dimer model ( J = –2.57(5) K), while5 unexpectedly formed a structural chain via Br…Br contacts which exhibits very weak antiferromagnetic interactions. An intermediate structure, (5BAP)(H2 O)CuBr2 (1 ), was prepared and characterized via mechanochemical methods along with an isomer of (5BAP)2 CuBr2 (2b ). Graphical Abstract: