Group 1 and 2 cyclic (alkyl)(amino)carbene complexes

Abstract

The first examples of cyclic (alkyl)(amino)carbene (CAAC) ligands bound to electropositive metal centres (K, Mg, Sr and Ba) have been isolated and characterised. Preliminary studies demonstrate that all complexes are active for polar monomer polymerisation under ambient conditions affording desirable hydroxyl-terminated telechelic polymers.

Transmetalation from Magnesium–NHCs—Convenient Synthesis of Chelating π-Acidic NHC Complexes

“…Complex 4 sa crystallized with a distorted pseudo-octahedral coordination geometry with the two bromido ligands in the apical positions and a coordinated pyridine molecule in the equatorial position. The magnesium-carbene bonds appeared unusually long (C1-Mg 2.311(2) Å, C2-Mg 2.301(2) Å), exceeding all previously reported magnesium carbene complexes in length [61,67,70]. Contrarily, the bond length between the central pyridine moiety and the metal (N1-Mg 2.162(2) Å) appeared to be in the common range for pyridine-coordinated magnesium complexes, as was also found for the coordinate pyridine molecule (N2-Mg 2.171(2) Å).…”

“…This is also true for magnesium, although the first example of an NHC-magnesium complex dates back to 1993 [56]. Subsequent investigations with s-block metals focused [57][58][59][60][61][62][63][64][65][66][67][68] largely on anionic ligands because of the weak magnesium-NHC bond [69][70][71][72][73][74]. For magnesium-NHC complexes, examples of saturated [75] and benzannulated [76,77] NHCs remain extraordinarily scarce.…”

Chemically Non‐Innocent Cyclic (Alkyl)(Amino)Carbenes: Ligand Rearrangement, C−H and C−F Bond Activation

“…Havingr ecentlyp repared the first examples of Group 1a nd 2 CAAC complexes, [22] and inspired by the report from Bertrand [a] Dr.…”

“…Having recently prepared the first examples of Group 1 and 2 CAAC complexes, and inspired by the report from Bertrand and co‐workers of a singlet biradicaloid zinc compound, we targeted the magnesium analogue ( CAAC)Mg. CAAC was first treated with MgCl 2 to yield the adduct ( CAAC)MgCl 2 . Subsequent addition of a further equivalent of carbene, followed by KC 8 at −78 °C resulted in a yellow solution upon slowly warming to room temperature.…”

Contemporary Molecular Barium Chemistry

“…The syntheses of both the donor free compound and its thf adduct have been thoroughly surveyed , , . However, some recent contributions examined the influence of the nature of various coordinated Lewis bases on the structure and the solution stability of [Ba{N(SiMe 3 ) 2 } 2 · (donor) x ] adducts , , . A structural comparison of the various adducts of Ba{N(SiMe 3 ) 2 } 2 is collated in Table and Figure ; the various ligands coordinated to the metal include di‐ and triamines, cyclic ethers, aminoethers and carbenes.…”