Crystal structure of [Cu(tmpen)](BF<sub>4</sub>)<sub>2</sub>{tmpen is<i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-tetrakis[(6-methylpyridin-2-yl)methyl]ethane-1,2-diamine}
Acta crystallographica. Section E, Crystallographic communications