Crystal engineering of a series of complexes and coordination polymers based on pyrazole-carboxylic acid ligands

Three new complexes namely [Cu(L1) H2O]center dot 2H(2)O (1), [Cu-2(L4)(2)(DMF)(2)(H2O)(2)](NO3)(2) (4) and [{Cd-2(L4)(2)Cl-2(DMF)(2)}] (5), and two coordination polymers namely [Co(mu-L2)(DMF)(2)]center dot H2O (2) and [Co(mu-L3)(DMF)(2)]center dot H2O (3) have been synthesized from a series of pyrazole-carboxylate ligands namely 1,1'-(ethane-1,2-diyl) bis(5-methyl-1H-pyrazole-3-carboxylic acid) (H(2)L1), 1,1'5-(oxybis`(ethane-2,1-diyl)) bis(5-methyl-1H-pyrazole-3carboxylic acid) (H(2)L2), 1,1'-(butane-1,4-diyl) bis(5-methyl-1H-pyrazole-3-carboxylic acid) (H(2)L3), and 2-(1',5,5'-trimethyl-1H, 1'H-[3,3'-bipyrazol]-1-yl) acetic acid (H(2)L4), and Cu-II/Cd-II/Co-II ions. Single crystal structures of these compounds are discussed in the context of the effect of conformation of the ligands and supramolecular interactions observed within these edifices. Temperature-dependent magnetic data of 4 could be fitted best using two non-interacting Cu-II ions (S = 1/2) per molecule with g(iso) = 2.28 and a temperature-independent paramagnetism, TIP = 1.75 x 10(-5) cm(3) mol(-1).