Synthesis, X-ray structures, and magnetic properties of copper(II) pyridinecarboxylate coordination networks

The three-dimensional Cu(II) coordination polymers [Cu(isonicotinate)(2)][EtOH] (1) and Cu(nicotinate)2 (2) were synthesized by treating copper nitrate with isonicotinic acid and nicotinic acid under hydro(solvo)thermal conditions, respectively. X-ray single-crystal structure determinations reveal that the Cu(II) centers in 1 adopt a slightly distorted square pyramidal geometry, while the Cu(II) centers in 2 exhibit a coordination geometry intermediate between square pyramid and trigonal bipyramid. The Cu(II) centers in 1 and 2 coordinate to both the pyridyl and carboxylate functionalities of the isonicotinate and nicotinate bridging ligands, respectively, to result in complicated 3-D framework structures. Compound 1 exhibits rhombic open channels that are occupied by removable ethanol molecules. Magnetic measurements indicated that 1 is a simple paramagnet with only very weak antiferromagnetic interactions, while 2 exhibits more pronounced antiferromagnetic interactions with J/k = -6.4 K. Crystal data for 1: monoclinic, space group Cc, a = 5.033(1) Angstrom, b = 24.855(5) Angstrom, c = 11.176(2) Angstrom, beta = 99.35(3)degrees, and Z = 4. Crystal data for 2: monoclinic, space group P2(1)/n, a = 10.693(2) Angstrom, b = 9.589(2) A, c = 12.535(3) beta = 112.09(3)degrees, and Z = 4.