title: Electronic structural trends in divalent carbon compounds.
abstract: This work aims to analyze and compare the intrinsic electronic densities in a series of neutral and anionic divalent carbon-donor derivatives. The σ-lone pair at the divalent carbon is the HOMO of these species. Structural factors have been identified that influence its energy, which is a measure of the σ-basicity. The π-electronic structure has been described as a function of the π-population. Our results show that no straightforward structural criteria correlate with the π-electronic distribution. However, the π-population, as well as the π-acidity and π-basicity, are related to the π-MOs. In all cases, these π-MOs can be qualitatively obtained on the basis of those of the protonated analogues by simply increasing the energy of the p(π) orbital at the divalent carbon atom compared to normal sp(2) carbon. Such an analysis allows a rationalization of the trends observed for the π-electronic structure of these ligands. Notably, this explains the values of the π-population at the divalent carbon center, which shows an increasing and continuous range from classical NHCs to mesoionic "carbenes".
authors.affiliation: Department of Chemistry, 3 Science Drive 3, National University of Singapore, Singapore 117543.
authors.forename: Han Vinh
authors.initials: HV
authors.lastname: Huynh
authors.forename: Gilles
authors.initials: G
authors.lastname: Frison