Honeycomb Nets with Interpenetrating Frameworks Involving Iminodiacetato−Copper(II) Blocks and Bipyridine Spacers: Syntheses, Characterization, and Magnetic Studies

Three coordination polymers of copper(II), viz. {[Cu(ida)(4,4‘-bipyH)]ClO4}∝ (1), {[Cu2(ida)2(μ-4,4‘-bipy)]·2H2O}∝
(2), and [Cu2(ida)2(bpa)]∝ (3) have been synthesized by the process of self-assembly using Cu(ida) [ida =
iminodiacetate(2-)] as the building block and 4,4‘-bipyridyl and 1,2-bis(4-pyridyl)ethane (bpa) as linkers. Crystals of
1 are orthorhombic, of space group Pna21, with a = 13.8956(12) Å, b = 16.3362(16) Å, c = 7.3340(12), and Z
= 4. Both compounds 2 and 3 crystallize in monoclinic space group P21/a with a = 10.1887(8) Å (9.6779(10) Å
for 3), b = 8.0008(11) Å (9.1718(10) Å), c = 11.6684(9) Å (12.9144(12) Å), β = 98.307(11)° (102.796(18)°), and
Z = 2 (2). Compound 1 has a zigzag chain structure with an extensive hydrogen-bonded network while compounds
2 and 3 are honeycomb (6,3) nets with interpenetrating structures. Variable temperature (2−300 K) magnetic study
indicates the presence of weak antiferromagnetic interactions (J = 0.82 ± 0.01 cm-1) in 1 and ferromagnetic in
2 (J = −0.45 ± 0.05 cm-1) and 3 (J = −0.21 ± 0.02 cm-1). The extent of planarity of the bridging “Cu−O−C−O−Cu” moiety, acting as the super-exchange pathway between the neighboring copper centers, probably controls
the sign of the magnetic exchange coupling in these compounds.