Quarato-bridged polymeric networks of iron(II) with N-donor coligands: Syntheses, crystal structures and magnetic properties

摘要

Two new squarato-bridged Fe(II) polymeric networks of molecular formula [Fe(squarate)(bpp)(2)(H2O)(2)] (1) and [Fe(squarate) (bpee)(H2O)(2)] (2) [bpp = 1,3-bis(4-pyridyl)propane; bpee = 1,2-bis(4-pyridyl)ethylene; squarate = C4O42-] have been synthesized and characterized by single-crystal X-ray diffraction studies and low temperature (300-2 K) magnetic measurements. Complex I is a 1D coordination chain of Fe(H2O)(2) units connected by mu-O,O" squarate dianions with monocoordinated bpp ligands dangling from the polymer. These ID chains ultimately transform to a thick 2D layer through pi-pi interaction of pyridyl rings as well as through hydrogen bonds. Whereas structural determination of complex 2 reveals an inclined interpenetrated 3D architecture. Magnetic data for both the complexes 1 and 2 have been fitted using the Fisher formula for S = 2 system and show antiferromagnetic coupling for both the complexes. The best fit parameters are J= -0.40 cm(-1), g = 2.30 and R = 0.01 for complex 1 and J = -0.49 cm(-1), g = 2.08 and R = 1.9 x 10(-3) for complex 2. (c) 2005 Elsevier B.V. All rights reserved.