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A Noninterpenetrated 1D Molecular Ladder and 2D Butterfly Network:  Effect of Positional Isomerism of Semirigid Bis(pyridylmethyl)pyromellitic Diimide Ligands on the Architecture of Their Metal(II) Complexes

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journal contribution
posted on 21.03.2005, 00:00 by Xing-Qiang Lü, Ji-Jun Jiang, Hans-Conrad zur Loye, Bei-Sheng Kang, Cheng-Yong Su
Three new complexes [Cd(4-pmpmd)1.5(NO3)2]·CHCl3 (1), [Cd(3-pmpmd)1.5(NO3)2]·EtOH (2), and [Zn(3-pmpmd)1.5(NO3)2]·MeOH (3) (3- or 4-pmpmd = N,N‘-bis(3- or 4-pyridylmethyl)pyromellitic diimide) containing T-shaped building blocks have been obtained from reactions between the long semirigid ligands 3- or 4-pmpmd and either cadmium or zinc nitrate. 1 forms noninterpenetrated 1D molecular ladders that are linked via multiple, complementary intermolecular C−H···O hydrogen bonds that effect the 3D alignment. 2 and 3 are isostructural and feature a noninterpenetrated 2D butterfly-shaped network with (6,3) topology. Multiple intermolecular C−H···O hydrogen bonds exist between the 2D layers and generate the 3D framework. The structural differences between 1 and 2 or 3 are attributed to the different conformations adopted by the ligands, which illustrate the influence of positional isomerism on the resultant supramolecular architectures of metal complexes.