Synthesis, Structure and Catalytic Activity of NHC-Ag(I) Carboxylate Complexes.

A general synthetic route was used to prepare 15 new N-heterocyclic carbene (NHC)-Ag(I) complexes bearing anionic carboxylate ligands [Ag(NHC)(O2 CR)], including a homologous series of complexes of sterically flexible ITent ligands, which permit a systematic spectroscopic and theoretical study of the structural and electronic features of these compounds. The complexes displayed a significant ligand-accelerated effect in the intramolecular cyclisation of propargylic amides to oxazolidines. The substrate scope is highly complementary to that previously achieved by NHC-Au and pyridyl-Ag(I) complexes.

Structure and bonding of [(SIPr)AgX] (X = Cl, Br, I and OTf).

A series of iso-structural complexes [(SIPr)AgX] (X = Cl, Br, I, OTf; SIPr = 1,3-bis(2,6-diisopropylphenyl)imidazolidene) were synthesised, including the first example of a N-heterocyclic carbene silver(I) complex containing an O-bound triflate. Bond Energy Dissociation and Natural Orbitals for Chemical Valence bond analyses (BEDA & ETS-NOCV) revealing a significant NHC → M σ-back-donation, which influences the stability and sigma-donicity of these complexes.

Silver-catalysed intramolecular hydroamination of alkynes with trichloroacetimidates.

Silver(I) complexes catalyse the intramolecular addition of trichloroacetimidates to alkynes. In the absence of a ligand, the selectivity of the reaction is dependent upon the nature of the counter-anion and solvent. The introduction of non-chelating nitrogeneous ligands suppresses competitive Brønsted acid catalysis, improving the yield and selectivity of the reaction.