Copper(II) halide salts and complexes of 4-amino-2-fluoropyridine: synthesis, structure and magnetic properties

Reaction of 4-amino-2-fluoropyridine (2-F-4-AP) with copper halides produced the neutral coordination complexes: (2-F-4-AP)(2)CuX2 (X=Cl(1), Br(2)). 1 crystallizes in the orthorhombic space group Pccn in a distorted square planar geometry. Magnetic susceptibility data were fit to the uniform chain Heisenberg model resulting in C=0.439(6)emu-K/mole-Oe and J=-28(1)K. 2 crystallizes in the monoclinic space group C2/m and is closer to distorted tetrahedral. Intermolecular BrCu contacts generate a square layer. Magnetic data show very weak ferromagnetic interactions [C=0.42(1)emu-K/mol-Oe, J=0.71(2)K]. Similarly, reaction of 2-F-4-AP with copper halides and aqueous HX in alcohol solvents produced the salts (2-F-4-APH)(2)CuX4 (X=Cl(3), Br(4)). 3 crystallizes in the triclinic space group P-1. Crystal packing reveals short ClCl contacts which generate a structural ladder. However, analysis of the magnetic data suggests that only the rails of the ladder produce a viable magnetic superexchange pathway; the uniform Heisenberg chain model provides C=0.449(1)emu-K/mol-Oe and J=-6.9(1)K. 4 is isostructural and is also best fit by a chain model [J=-2.7(4)K]. The brominated complex (2-F-3-Br-4-APH)(2)CuBr(4)2H(2)O, 5, (2-F-3-Br-4-APH=4-amino-3-bromo-2-fluoropyridinium) was serendipitously produced as a byproduct of the synthesis of 4 and was characterized by single-crystal X-ray diffraction. [GRAPHICS]