Double CH Bond Activation of C(sp³)H₂ Groups for the Preparation of Complexes with Back‐to‐Back Bisimidazolinylidenes

Abstract

Zweiköpfige Carbene: Komplexe von N‐heterocyclischen Carbenen mit Rhodium und Iridium wurden durch die doppelte C‐H‐Aktivierung von CH2‐Gruppen in N‐Heterocyclen erhalten (siehe Struktur; C grau, N blau, Cl grün, Ir pink). Diese Reaktion bietet einen nützlichen Ansatz zur Herstellung neuartiger Carbenliganden.

Pyracene‐Linked Bis‐Imidazolylidene Complexes of Palladium and Some Catalytic Benefits Produced by Bimetallic Catalysts

“…An important class of bis(NHCs) features two facially opposed carbenes that inhibit chelation, thereby facilitating structures in which the ligand is bridging two transition metals that can be comprised in a discrete molecule or in a polymeric system 2. Some representative examples of this type of bis(NHCs) include triazolylidenes,3 benzobis(imidazolylidenes),4 oxanthrobis(imidazolylidenes),4b quinobis(imidazolylidenes),4d, e bis(imidazolinylidenes),5 and our recently described pyracenebis(imidazolylidene) 6. Such types of biscarbenes, especially those linked by rigid π‐conjugated systems, enable electronic communication between the carbene units, which can allow for interesting applications in molecular electronic devices.…”

A Twisted Tetragold Cyclophane from a Fused Bis-Imidazolindiylidene

“…The flexibility of this apparently rigid connector made us think that the carbazolyl-bis-alkynyl unit could be used as a versatile and adaptable building block for the construction of supramolecular structures combined with other rigid, yet not planar, di-NHC ligands. Rigid angular di-NHC ligands are rare, but some years ago we described a bis-imidazolindiylidene ligand (C) that was coordinated to rhodium and iridium 9 and then to palladium. 10 Depending on the steric congestion brought about the metal coordination sphere, the angle between the planes of the two fused NHC rings could vary in the range of 109.7−116.4°.…”

Alternative Natrium

“…Metal complexes of NR,NR‐functionalized NHCs ( A ; NHC=N‐heterocyclic carbene; Scheme ) have been obtained by the direct reaction of the free NHCs with suitable transition metal complexes,1, 2 by the cleavage of enetetramines with transition metal precursors,3 by the oxidative addition of the C2X bond (X=H, alkyl, halogen, SR) of azolium cations to low‐valent transition metals4a–g and by double CH bond activation in imidazolidines 4h,i. Metal complexes bearing protic NHCs that is, NHCs featuring an NH,NR‐ ( B ) or NH,NH‐substitution pattern ( C ) have received less attention.…”