Abstract:
Despite the first 1,4-diphosphinine was published in 1976, isolated tricyclic imidazole-based dithione and -selone derivatives were synthesised only recently. They readily undergo reactions with nucleophiles as well as [4+2]-cycloadditions, while only their 1,4-dihydro-1,4-diphosphinine precursors have been converted into planar P-bridged bis(N-heterocyclic) carbenes (bis-NHCs). The latter were investigated regarding their reactivity towards transition metal complexes and, hence, represent interesting tetratopic ligands.
Herein, the synthesis of new rigid, bent bis-NHCs is presented. Their reactivity towards metal complexes and main group element halides will be discussed and compared to that of already established bis-NHCs, including some surprises.