Chemistry

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

Claire A. Krasinski, Clark University
Benjamin L. Solomon, Clark University
Firas F. Awwadi, The University of Jordan
Christopher P. Landee, Clark University
Mark M. Turnbull, Clark University
Jan L. Wikaira, University of Canterbury

Abstract

Reaction of 4-amino-2-fluoropyridine (2-F-4-AP) with copper halides produced the neutral coordination complexes: (2-F-4-AP)2CuX2 (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 Br⋯Cu 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)2CuX4 (X = Cl(3), Br(4)). 3 crystallizes in the triclinic space group P-1. Crystal packing reveals short Cl⋯Cl 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)2CuBr4·2H2O, 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.