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)).