Amidine- and amidinate-functionalised N-heterocyclic carbene complexes of silver and chromium

Abstract

A new family of N,N′-bis-(2,6-diisopropylphenyl)-(2,6-diisopropylphenyl-imidazolium)-acetamidines have been developed as NHC proligands and ligands that are functionalised with neutral amidine and anionic amidinato moieties. On coordination they adopt diverse binding modes, depending on the nature of the metal and the reaction conditions. In the Ag, K and Cr complexes reported in this paper, monodentate κ¹(NHC), bimetallic bridging-(κ¹-NHC–κ¹-amidinato) and bidentate (κ¹-NHC–κ¹-amidinato) binding modes were observed, respectively. Two of the novel Cr complexes, in the presence of activators, were tested as catalysts for the polymerisation of ethylene showing low activity.