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

The bimetallic copper­(I) complex Cu2L2 (cis-1) is formed with high diasteroselectivity from [Cu­(NCCH3)4]­[BF4] and HL (4-tert-butyl phenyl­(pyrrolato-2-yl-methylene)­amine) in a kinetically controlled reaction. cis-1 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 cis-1 yields elemental copper and the mononuclear copper­(II) complex CuL2 (trans-2). One-electron reduction of trans-2 gives cuprate [2]– with a bent bis­(pyrrolato) coordinated copper­(I) entity. The imine donor atoms of [2]– can insert an additional copper­(I) ion giving exclusively the bimetallic complex cis-1 closing the oxidation–elimination–reduction–insertion cycle.