Group 10 and group 11 transition metal chemistry of benzimidazolin-2-ylidene and indazolin-3-ylidene ligands

Abstract

The chemistry of N-heterocyclic carbenes (NHCs) has experienced a rapid development over the last two decades. This is mainly due to their strong ¿-electron donating property and nucleophilicity, which makes them perfectly suitable as ligands in organometallic chemistry. Most studies on metal NHC complexes are based on imidazolin-2-ylidene and imidazolidin-2-ylidene ligands. However, less attention has been paid for complexes derived from benzimidazolin-2-ylidenes and their metal complexes. Hence, in order to extend the scope of benzimidazolin-2-ylidene ligands, metal complexes of the latter bearing non-halo anionic co-ligands have been synthesized and investigated for their further reactivity and catalytic activity. In addition, the synthesis of stronger donating carbenes is of considerable interest. In this regard, a series of transition metal complexes bearing indazolin-3-ylidenes as a new class of NHC ligands, have been prepared and characterized. Donor strength evaluation of indazolin-3-ylidene ligands revealed that the latter can be regarded as one of the strongest donors among five membered NHCs.