Preparation, spectroscopic and X-ray study of [Cu2(Hdmg)4 (γ,γ′-dpy)]2 · 4H2dmg and [Cu2(Hdmg)4 · (γ,γ′-dpy)] · [Cu(Hdmg)2 · (γ,γ′-dpy)] · (γ,γ′-dpy) 2H2dmg

Two novel Cu(II) dimethylglyoximato complexes of the compositions [Cu2(Hdmg)4 · (γ,γ′-dpy)]2 · 4H2dmg (1) and [Cu2(Hdmg)4 · (γ,γ′-dpy)] · [Cu(Hdmg)2 · (γ,γ′-dpy)] · (γ,γ′-dpy).2H2dmg (2) (H2dmg = dimethylglyoxime, γ,γ′-dpy = γ,γ′-dipyridine) were synthesized and their crystal structures were determined by single-crystal X-ray diffraction. The structure of 1 consists of the neutral [Cu2(Hdmg)4 · (γ,γ′-dpy)] binuclear units and non-coordinated H2dmg molecules. The structure of 2 consists of neutral [Cu2(Hdmg)4 · (γ,γ′-dpy)] binuclear and [Cu(Hdmg)2 · (γ,γ′-dpy)] mononuclear units and non-coordinated H2dmg and γ,γ′-dpy molecules. Both in copper(II) dimers and monomers the environment around copper atoms is distorted square pyramidal with four oximate nitrogen atoms building the equatorial plane. A nitrogen atom from γ,γ′-dpy molecule occupies the apical position of the square pyramids around Cu. The Cu(1)⋯Cu(2) separation in the dimers are 11.465(1), 11.431(1) Å in 1 and 11.472(2) Å in 2. In both 1 and 2 the neutral species are packed in such a way as to maximize the hydrogen bonding and π–π stacking interactions between the crystal components.