Polymeric networks of copper(II)using succinate and aromatic N-N donor ligands: synthesis,crystal structure,magnetic behaviour and the effect of weak interactions on their crystal packing

摘要

Four succinato-bridged complexes of copper(II)have been synthesized.Complex 1,[Cu_2(mu-OH_2)_2L(bpy)_2(NO)_3)_2]_n and 2,[Cu_2(mu-OH_2)_2L(phen)_2(NO_3)_2]_n(bpy=2,2'-bipyridine; phen=1,10-phenanthroline and LH_2=succinic acid)exhibit ID coordination polymer structures where both the nitrate ions are directly linked to the copper(II)producing synthons in a 2D sheet.A novel 2D grid-like network,{[Cu_4L_2(bpy)_4(H_2O)_2](ClO_4)_4(H_2O)}_n 3,is obtained upon changing the nitrate by perchlorate anion in complex 1,where the channels are occupied by the anions.On changing the nitrate by tetrafluoroborate anion in complex 2,a novel octanuclear complex,[Cu_8L_4(phen)_12](BF4)_8(center dot)8H_2O 4,is isolated.The coligand bpy and phen in these complexes show face-to-face(in 1,2,3,4)or edge-to-face(in 4)pi-PI interactions forming the multidimensional supramolecular architectures.Interestingly,the appearance of edge-to-face pi-pi interactions in complex 4 facilitates the formation of discrete octanuclear entities.Variable-temperature(300-2 K)magnetic measurements of complexes have been done.Complexes 1 and 2 show very weak antiferromagnetic(OOC-CH_2-CH_2-COO)and ferromagnetic coupling(mu-H_2O).Complex 3 also shows antiferromagnetic(syn-syn mu-OCO),and ferromagnetic coupling(mu-O of the-COO group).Complex 4 with two types(syn-syn and syn-anti)of binding modes of the carboxylate group shows strong antiferromagnetic interaction.