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) Å, b = 24.855(5) Å, c = 11.176(2) Å, β = 99.35(3)°,
and Z = 4. Crystal data for 2:  monoclinic, space group P21/n, a = 10.693(2) Å, b = 9.589(2) Å, c = 12.535(3) Å, β =
112.09(3)°, and Z = 4.