Low-dimensional compounds containing cyanide groups. XXVI. (Dicyanamido-κN(1))bis(5,5'-dimethyl-2,2'-bipyridine-κ(2)N,N')copper(II) complexes with tetrafluoroborate and perchlorate anions.

(Dicyanamido-κN(1))bis(5,5'-dimethyl-2,2'-bipyridine-κ(2)N,N')copper(II) tetrafluoroborate, [Cu{N(CN)2}(C12H12N2)2]BF4, (I), and (dicyanamido-κN(1))bis(5,5'-dimethyl-2,2'-bipyridine-κ(2)N,N')copper(II) perchlorate, [Cu{N(CN)2}(C12H12N2)2]ClO4, (II), are isomorphous and consist of [Cu{N(CN)2}(mbpy)2](+) cations (mbpy is 5,5'-dimethyl-2,2'-bipyridine) and BF4(-) or ClO4(-) anions, respectively. The Cu(II) cations in both structures are five-coordinated in distorted trigonal bipyramidal environments by four N atoms of two mbpy ligands and one N atom of the dicyanamide anion, which is coordinated in a monodentate manner in the equatorial plane, with Cu-N distances of 1.980 (3) and 1.977 (2) Å in (I) and (II), respectively. The two axial Cu-Nmbpy bonds have very similar values [1.986 (1) Å on average] and are shorter than the other two equatorial Cu-Nmbpy bonds. These have different values in the individual compounds but nevertheless form two pairs of similar bonds in (I) and (II) [2.066 (8) and 2.112 (2) Å, respectively, on average]. Besides the ionic forces in both structures, the structures are stabilized by C-H...N and C-H...X hydrogen bonds (X = F and O, respectively), and by π-π interactions between the pyridine rings of neighbouring mbpy molecules.