Photochemistry and Redox Chemistry of an Unsymmetrical Bimetallic Copper(I) Complex

The bimetallic copper­(I) complex Cu₂<b>L</b>₂ (<i><b>cis</b></i><b>-1</b>) is formed with high diasteroselectivity from [Cu­(NCCH₃)₄]­[BF₄] and <b>HL</b> (4-<i>tert</i>-butyl phenyl­(pyrrolato-2-yl-methylene)­amine) in a kinetically controlled reaction. <i><b>cis</b></i><b>-1</b> features a rather short Cu···Cu distance of 2.4756(6) Å and is weakly emissive at room temperature in solution. Oxidatively triggered disproportionation of <i><b>cis</b></i><b>-1</b> yields elemental copper and the mononuclear copper­(II) complex Cu<b>L</b>₂ (<i><b>trans</b></i><b>-2</b>). One-electron reduction of <i><b>trans</b></i><b>-2</b> gives cuprate <b>[2]</b>^<b>–</b> with a bent bis­(pyrrolato) coordinated copper­(I) entity. The imine donor atoms of <b>[2]</b>^<b>–</b> can insert an additional copper­(I) ion giving exclusively the bimetallic complex <i><b>cis</b></i><b>-1</b> closing the oxidation–elimination–reduction–insertion cycle