Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)₂CuX₂ and (3,5-FCAPH)₂CuX₄

Abstract

Using 2-amino-5-chloro-3-fluoropyridine, two new copper halide coordination complexes and two new salts have been synthesized: [(3,5-FCAP) 2 CuCl 2 ] (1), [(3,5-FCAP) 2 CuBr 2 ](2), (3,5-FCAPH) 2 (3) and (3,5-FCAPH) 2 [CuBr 4 ] (4) [3,5-FCAP = 2-amino-5-chloro-3-fluoropyridine; 3,5-FCAPH = 2-amino-5-chloro-3-fluoropyridinium]. These complexes have been analyzed throughThe reaction of 2-amino-5-chloro-3-fluoropyridine (3,5-FCAP) with copper(II) halides in neutral or acidic media gave the complexes (3,5-FCAP) 2 CuX 2 and (3,5-FCAPH) 2 CuX 4 (X = Cl, Br). Variable temperature magnetic susceptibility reveals anti-ferromagnetic interactions, J, ranging from −0.9 to −31.3 K.single-crystal X-ray diffraction and temperature-dependent magnetic susceptibility. Compounds 1 and 2 crystallize in the triclinic space group P-1, while 3 and 4 crystallize in the monoclinic space group P2 1 /c. All structures were distinct, with 1 giving a bihalide bridged chain, 2 yielding a halide bridged dimer, 3 forming a two-halide bridged chain via short Cl⋅⋅⋅Cl contacts, and 4 producing a rectangular sheet via short Br⋅⋅⋅Br contacts. All four compounds exhibit anti-ferromagnetic interactions and were fit to linear chain (1 and 3), dimer (2), and rectangular 2-D sheet (4) models. The resulting J/k B values are −3.4(1), −31.3(8), −0.9(1), and −9.46(6) K with an α value (α = Jʹ/J) of 0.06(2), respectively.

1D and 3D supramolecular structures exhibiting weak ferromagnetism in three Cu(II) complexes based on malonato and di-alkyl-2,2’-bipyridines

“…Hydrogen-bond magnetic interactions have been reported previously for other Cu(II) complexes and polymers, including malonate or its derivatives and have been described exhibiting both antiferromagnetic behavior [32,41,42] and ferromagnetic exchange [26,29,40,[43][44][45]. Therefore, according to the above mentioned, the obtained values for the exchange coupling constant (vide supra) for the three complexes are in agreement with those recently reported for Cu(II) complexes having hydrogen bonding or other intermolecular interactions [46][47][48][49][50][51].…”

“…Thence, 1, 2, and 3 exhibit weak ferromagnetic exchange interactions between the Cu(II) centers throughout the main hydrogen bond interactions occurring in supramolecular arrays, in agreement with the fitted magnetic data showing only one significant exchange pathway [46]. Therefore, it is still important, from the point of view of the magnetochemistry, to keep investigating this special coupling via hydrogen-bond interactions in supramolecular frameworks of this kind of complexes.…”

Copper(II) Halide Salts with 1-(4′-Pyridyl)-Pyridinediium

“…The CuX 4 2− unit in 2 may be comparably described as a flattened tetrahedron or a distorted square planar unit with a mean trans angle [28] in 1 = 144.9 • and in 2 = 142.9 • (the corresponding τ 4 parameters are 0.53 (1) and 0.50 (2) [29]. The Cu-X bond lengths are those expected for a CuX 4 2− unit [13][14][15][16][17][18][19][20][21][22][23][24];…”

“…The importance of the bifurcated CuCl 2 •••H-N hydrogen bond was also shown by Yahsi et al [12] with a variety of boronic acid cations for crystal engineering. Given our previous work with pyridinium salts of tetrahalidocuprate ions [13][14][15][16][17][18], we were intrigued with the potential for observing and using such hydrogen bonding in the formation of low-dimensional lattices for magnetic study. In many tetrahalidocuprate compounds [13][14][15][16][17][18][19][20][21][22][23][24], the general formula may be written as (BH) 2 [CuX 4 ] where B is an organic base, most often an amine.…”

“…Given our previous work with pyridinium salts of tetrahalidocuprate ions [13][14][15][16][17][18], we were intrigued with the potential for observing and using such hydrogen bonding in the formation of low-dimensional lattices for magnetic study. In many tetrahalidocuprate compounds [13][14][15][16][17][18][19][20][21][22][23][24], the general formula may be written as (BH) 2 [CuX 4 ] where B is an organic base, most often an amine. The BH + moiety provides charge balance and influences the structure of the crystal lattice through its steric and electronic properties.…”