Diversity of supramolecular aggregation in copper(II) pentane-2,4-dionato compounds with methyl substituted 2-aminopyridines

Three copper(II) bis(pentane-2,4-dionato-κ ² O,O′) compounds with 2-amino-3-methylpyridine (2,3-ampy) (1), 2-amino-5-methylpyridine (2,5-ampy) (2), and 2-amino-4-methylpyridine (2,4-ampy) (3) were prepared by reaction of bis(pentane-2,4-dionato-κ ² O,O′)copper(II) with selected methyl substituted 2-aminopyridines. The coordination of Cu(II) in all three compounds is square pyramidal and intramolecular N–H?···?O hydrogen-bonding is present. X-ray crystallographic studies reveal different crystal aggregation influenced by a methyl substituent on pyridine. No intermolecular N–H?···?O hydrogen-bonding is present in 1. Intermolecular N–H?···?O hydrogen-bonding in 2 forms infinite chains and dimers are formed in 3. Extended 3-D aggregation was found in 2 via π–π and C–H?···?π (arene) interactions, while only chain formation was found in 1 and 3.