Construction of tube- and ladderlike Copper(II) coordination polymers based on the nicotinato tecton

Three 1-D copper(II) coordination polymers have been obtained by using the nicotinato anion (NA(-)) as a bridge, and 2,2'-bipyridine or dicyanamide (dca) as coligands: [Cu-1(infinity)2(bipy)(2)(NA)(2)](ClO4)(2)center dot H2O 1, [Cu-1(infinity)2(Me(2)bipy)(2)(NA)(2)](ClO4)(2) 2, [Cu-1(infinity)3(NA)(4)(dca)(2)(H2O)(8)]center dot 2H(2)O 3 (bipy = 2,2'-bipyridine; Me(2)bipy = 4,4'-dimethyl-2,2'-bipyridine, dca = dicyanamide anion). The metal-ligand association in compounds 1 and 2 is very similar and generates tubelike coordination polymers, which are constructed from pairs of copper atoms connected through two carboxylato groups from two NA(-) ligands. Each pyridyl moiety from the NA(-) ligand coordinates at the apical position of the copper ions from another pair, resulting in chains running along the crystallographic c axis. The structure of 3 consists of infinite ladderlike chains: the rungs are formed by trinuclear [Cu-3] moieties, with the copper(II) ions connected through NA- bridges, the ladder sides being constructed from dca(-) bridging ligands. The cryomagnetic investigation of the three compounds reveals weak antiferromagnetic interactions mediated by the nicotinato ligand, 1: J = -7.3 cm(-1), 2: -15.3 cm(-1), 3: -0.58 cm(-1).