Nickel adipate coordination polymers with isomeric dipyridylamide ligands: topological disorder and divergent magnetic properties

Abstract

Hydrothermal reaction of nickel nitrate, adipic acid, and a dipyridylamide ligand produced two coordination polymers which were structurally characterized by single-crystal X-ray diffraction. {[Ni₂(adipate)₂(3-pna)₂(H₂O)]·H₂O}_n (1, 3-pna = 3-pyridylnicotinamide) possesses carboxylate bridged {Ni(μ₂-H₂O)(OCO)₂} dimeric units connected into (6,3) graphitic 2D layer motifs. Use of the isomeric 3-pyridylisonicotinamide (3-pina) afforded {[Ni₂(adipate)₂(3-pina)₂(H₂O)]·2H₂O}_n (2), which manifested similar {Ni(μ₂-H₂O)(OCO)₂} dimeric units. Crystallographic disorder within the adipate ligands in 2 produced a 3D coordination polymer net that is a hybrid of a non-interpenetrated 3D 6-connected primitive cubic α-Po 4¹²6³pcu net and 2D 7-connected slab motifs with a pillared (3,6) triangular net 3⁶4¹²5³ topology. Magnetic analysis for 1 revealed weak antiferromagnetic coupling (J = −0.36(1) cm⁻¹ with g = 2.077(1)), while 2 exhibited weak ferromagnetic coupling (J = +0.51(2) cm⁻¹ with g = 2.034(7)).