Two dimeric CuII benzoate derivatives solvated with acetonitrile

The title compounds, tetrakis(micro-benzoato-O:O')bis(2,6-diaminopyridine)-1kappaN,2kappaN-dicopper(II)-acetonitrile (1/2), [Cu(2)(C(7)H(5)O(2))(4)(C(5)H(7)N(3))(2)].2C(2)H(3)N, (I), and bis(acetonitrile)-1kappaN,2kappaN-tetrakis(micro-benzoato-O:O')dicopper(II)-acetonitrile (1/1.5), [Cu(2)(C(7)H(5)O(2))(4)(C(2)H(3)N)(2)].1.5C(2)H(3)N, (II), crystallize as acetonitrile solvates exhibiting different stability. They have similar molecular structures with discrete dimeric units located at crystallographic inversion centres. The copper ions are bridged by four benzoate groups and neutral N-donor ligands, viz. 2,6-diaminopyridine in (I) and acetonitrile in (II), are coordinated at apical positions. The diverse stability is probably due to hydrogen-bond interactions of the solvated acetonitrile molecules with neighbouring dimers in compound (I).