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: 

Cu2(bipy)2(NA)2](ClO4)2·H2O 1,

Cu2(Me2bipy)2(NA)2](ClO4)2 2,

Cu3(NA)4(dca)2(H2O)8]·2H2O 3 (bipy = 2,2‘-bipyridine; Me2bipy = 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 [Cu3] 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.