Alkali and alkaline-earth metal complexes of different nuclearities with azamacrocyclic pendant-arms ligands

A new series of alkali and alkaline-earth complexes of Na(I), Ca(II), Sr(II) and Ba(II) with two pyridyl pendant-arms azamacrocyclic ligands, L1 and L2, were synthesized by reaction of the ligand and the appropriate perchlorate salt in refluxing acetonitrile. The reactions gave analytically pure products that were characterized by elemental analysis, FAB mass spectrometry, IR, conductivity measurements and 1H NMR spectroscopy. The crystal structure of [NaL1](ClO4), [BaL1](ClO4)2 · 2CH3CN and [Ca2L2(μ-ClO4)(H2O)2](ClO4)2 · Cl · (H2O)0.5 could be also determined. The crystal structure of the Na(I) and Ba(II) complexes with L1 show endomacrocyclic mononuclear species, where the metal ions are in N8 and N10 coordination environment, respectively. The geometry around the metal ions can be described as cube and bicapped cube geometry for Na(I) and Ba(II), respectively. Instead, the crystal structure of the Ca(II) compound with L2 shows an exomacrocyclic dinuclear complex where both metal ions are in a similar N5O2 environment joined through a bidentate perchlorate anion. The coordination geometry for both Ca(II) ions can be described as distorted pentagonal bipyramid.