Issue 2, 2004

Synthesis, structural analysis, and magnetic behaviour of three fumarate bridged coordination polymers: five-fold interpenetrated diamond-like net of NiII, sheets of NiII and CoII

Abstract

The hydrothermal reactions of Ni(NO3)2·6H2O, disodium fumarate (fum) and 1,2-bis(4-pyridyl)ethane (bpe)/1,3-bis(4-pyridyl)propane (bpp) in aqueous–methanol medium yield one 3-D and one 2-D metal–organic hybrid material, [Ni(fum)(bpe)] (1) and [Ni(fum)(bpp)(H2O)] (2), respectively. Complex 1 possesses a novel unprecedented structure, the first example of an “unusual mode” of a five-fold distorted interpenetrated network with metal–ligand linkages where the four six-membered windows in each adamantane-type cage are different. The structural characterization of complex 2 evidences a buckled sheet where nickel ions are in a distorted octahedral geometry, with two carboxylic groups, one acting as a bis-chelate, the other as a bis-monodentate ligand. The metal ion completes the coordination sphere through one water molecule and two bpp nitrogens in cis position. Variable-temperature magnetic measurements of complexes 1 and 2 reveal the existence of very weak antiferromagnetic intramolecular interactions and/or the presence of single-ion zero field splitting (D) of isolated NiII ions in both the compounds. Experimentally, both the J parameters are close, comparable and very small. Considering zero-field splitting of NiII, the calculated D values are in agreement with values reported in the literature for NiII ions. Complex 3, [{Co(phen)}2(fum)2] (phen = 1,10-phenanthroline) is obtained by diffusing methanolic solution of 1,10-phenanthroline on an aqueous layer of disodium fumarate and Co(NO3)2·6H2O. It consists of dimeric CoII(phen) units, doubly bridged by carboxylate groups in a distorted syn–syn fashion. These fumarate anions act as bis-chelates to form corrugated sheets. The 2D layer has a (4,4) topology, with the nodes represented by the centres of the dimers. The magnetic data were fitted ignoring the very weak coupling through the fumarate pathway and using a dimer model.

Graphical abstract: Synthesis, structural analysis, and magnetic behaviour of three fumarate bridged coordination polymers: five-fold interpenetrated diamond-like net of NiII, sheets of NiII and CoII

Article information

Article type
Paper
Submitted
26 Sep 2003
Accepted
19 Nov 2003
First published
10 Dec 2003

Dalton Trans., 2004, 260-266

Synthesis, structural analysis, and magnetic behaviour of three fumarate bridged coordination polymers: five-fold interpenetrated diamond-like net of NiII, sheets of NiII and CoII

S. Konar, E. Zangrando, M. G. B. Drew, J. Ribas and N. Ray Chaudhuri, Dalton Trans., 2004, 260 DOI: 10.1039/B311988B

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