Synthesis, spectral and magnetical characterization of monomeric [Cu(2-NO2bz)2(3-pyme)2(H2O)2] and polymeric [Cu{3,5-(NO2)2bz}2(3-pyme)2]n

Two new complexes of composition [Cu(2-NO2bz)2(3-pyme)2(H2O)2] (1) and/or [Cu{3,5-(NO2)2bz}2(3-pyme)2] (2) (3-pyme = 3-pyridylmethanol, ronicol or 3-pyridylcarbinol, 2-NO2bz = 2-nitrobenzoate and 3,5-(NO2)2bz = 3,5-dinitrobenzoate) have been prepared and studied by elemental analysis, electronic, infrared and EPR spectroscopy, magnetic susceptibility measurements and the structure of both complexes has been solved. Complex (1) shows an unusual molecular type of structure consisting of the [Cu(2-NO2bz)2(3-pyme)2(H2O)2] molecules held together by hydrogen bonds and van der Waals interactions. Complex (2) exhibits a polymeric chain-like structure [Cu{3,5-(NO2)2bz}2(3-pyme)2]n with copper atoms doubly bridged by two 3-pyridylmethanol molecules and the polymeric molecules are held together by van der Waals interactions. Complex (1) exhibits a magnetic moment μeff = 1.84 B.M. at 300 K that remains nearly constant within the temperature region (5–300 K). Further cooling results in lowering the magnetic moment to μeff = 1.82 B.M. at 1.8 K. The magnetic susceptibility temperature dependence obeys Curie–Weiss law with Curie constant of 0.423 cm3 K mol−1 and with Weiss constant of −0.06 K. The magnetic moment of (2) exhibits a small increase with a decrease in the temperature (μeff = 1.80 B.M. at 300 K and μeff = 1.85 B.M. at 1.8 K) with Curie constant of 0.409 cm3 K mol−1 and with Weiss constant of +1.1 K, which can indicate a very weak ferromagnetic interaction between the copper atoms within the chain. Applying the molecular field model resulted in obtaining zJ′ values −0.08 cm−1 for complex (1), and −0.07 cm−1 for complex (2), respectively, that could characterize intermolecular and interchain interactions transmitted through π–π stacking.