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

Abstract

The bimetallic copper(I) complex CuL (cis-1) is formed with high diasteroselectivity from [Cu(NCCH)][BF] 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 CuL (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.

Alkali Blues: Blue‐Emissive Alkali Metal Pyrrolates

“…The centrosymmetric arrangement of the dimeric core [Li( t Bu L)] 2 is similar to the few reported structures of alkali metal‐pyrrolate complexes (Scheme ) and to the solid‐state structure of the parent ligand H t Bu L, which crystallizes as a centrosymmetric hydrogen‐bridged dimer (H t Bu L) 2 (Scheme ) . These centrosymmetric dimers, [Li( t Bu L)] 2 and (H t Bu L) 2 , differ from the C 2 ‐symmetric copper(I) dimer [Cu( t Bu L)] 2 (Scheme ) . Within complex [ 1 (CH 3 CN)] 2 , all Li−N bond lengths are quite similar [Li1−N1 2.095(2), Li1−N2 2.064(2), Li1−N1′ 2.076(3), and Li1−N3 2.044(3) Å; Supporting Information, Table S2].…”

“…In both cases, the iminopyrrole units are almost planar with N1‐C4‐C5‐N2 torsion angles of 4.4(2)° and 1.8(2)° for [ 1 (CH 3 CN)] 2 and [ 1 (H 2 NC(CH 3 )CHCN)] 2 , respectively. Such a planar orientation is typical for N , N′ ‐chelated 2‐iminopyrrolates . The C5‐N2‐C6‐C7 aryl torsion angles of [ 1 (CH 3 CN)] 2 and [ 1 (H 2 NC(CH 3 )CHCN)] 2 amount to 35.96(15)° and 27.76(14)°, respectively.…”

“…[21] These centrosymmetric dimers, [Li( tBu L)] 2 and (H tBu L) 2 ,d iffer from the C 2 -symmetric copper(I) dimer [Cu( tBu L)] 2 (Scheme 1). [22] (5) ]i sl onger than that in [1(CH 3 CN)] 2 .I nb oth cases, the iminopyrroleu nits are almost planarw ith N1-C4-C5-N2 torsion angles of 4.4(2)8 and 1.8(2)8 for [1(CH 3 CN)] 2 and [1(H 2 NC(CH 3 )CHCN)] 2 ,r espectively. Such a planar orientation is typical for N,N'-chelated 2-iminopyrrolates.…”

“…For example, they have been applied in transition metal or lanthanide complexes, which are used as homogenous catalysts, especially for polymerization, and as biomimetic and bioinspired complexes [e.g. Mo( t Bu L) 2 O 2 or [Cu( t Bu L)] 2 ; H t Bu L=4‐ tert ‐butyl phenyl(pyrrol‐2‐ylmethylene)amine; Scheme ] . The high interest in this class of bidentate ligands is rooted in the design flexibility and ease of synthesis because physicochemical, electronic, and steric features can be tuned in a straightforward manner.…”

“…Mo( tBu L) 2 O 2 or [Cu( tBu L)] 2 ;H tBu L = 4-tert-butyl phenyl(pyrrol-2-ylmethylene)amine;S cheme 1]. [19][20][21][22] The high interest in this class of bidentate ligands is rootedi nt he design flexibility and ease of synthesis because physicochemical, electronic, and steric features can be tuned in as traightforwardm anner.E ven redox-active 2-iminopyrrolates decorated with ferrocenyl substituents and polymer-immobilized ligandsh ave been devised ands uccessfully employedi nb ioinspired molybdenum-based catalysts. [23][24][25] Although the syntheses of the majority of the transition metal and rare-earth metal complexes of these ligands are based on the deprotonation of the ligandsH Lw ith strong bases like nBuLi, NaH or KHMDS( potassium hexamethyldisilazide), the alkali metal complexes have only been rarely studied andc haracterized.…”