The First Nonclassical Distonic Ion

Abstract

The gaseous and ionized prototype carbonyl ylide, the distonic ion +CH2−O−CH2•, is found to transfer ionized methylene to 1-adamantylphosphaacetylene (1-Ad−C⋮P), a kinetically stabilized phosphaalkyne, thus forming the 1-adamantylphosphaacetylenium P-methylide ion, 1-Ad−C+P−CH2•, a novel phosphorus, and the first nonclassical distonic ion. The ion abstracts CH3S• from CH3SSCH3 and both Br• and C3H5• from allyl bromide, and this characteristic reactivity demonstrates its distonic character. MO calculations at the Becke3LYP/6-311G(d,p) and MCSCF [CAS(3,3)] levels confirm that 1-Ad−C+P−CH2• bears spatially separated charge and odd spin sites. They also reveal for the ion a phosphaallylic radical structure that stabilizes the radical site, and a σ-bridged structure with three-center two-electron bonds that stabilizes the charge site. This unique electronic structure characterizes 1-Ad−C+P−CH2• as the first nonclassical distonic ion.