ring strain

Probing the Origin of Ambiphilic Reactivity in Osmapentalyne Complexes: Interplay of Ring Strain, Aromaticity, and Phosphonium Substituent

Ambiphilic reactivity is a fascinating topic in chemical reactions, attracting considerable interest because ambiphilic reagents can display properties of both nucleophilicity and electrophilicity. However, most of the previous attention has been focused on the characterization of the ambiphilic reactivity, whereas the origin is less understood. Here we carry out thorough density functional theory (DFT) calculations to probe the origin of the ambiphilic reactivity of the carbyne atom in osmapentalynes, observed previously in experiment.

To Be Bridgehead or Not to Be? This is a Question of Metallabicycles on the Interplay between Aromaticity and Ring Strain

Transition-metal-containing metallaaromatics have attracted considerable interest from both experimental and computational chemists because they can display properties of both organometallic compounds and aromatic organic compounds. In general, the transition metal in a metallabicycle prefers a nonbridged position to the bridgehead one because of the larger ring strain caused by the rigidity in the bridgehead position, as exemplified by metallanaphthalene and metallanaphthalyne.

Evaluation of Triplet Aromaticity by the Indene–Isoindene Isomerization Stabilization Energy Method

Aromaticity, one of the most important concepts in chemistry, has attracted considerable interest from both experimentalists and theoreticians. According to Baird's rule, triplet annulenes with 4n π electrons are aromatic. However, the approach to evaluate the magnitude of the triplet aromaticity is less developed. Herein we apply the indene–isoindene isomerization stabilization energy (ISE) method to evaluate the aromaticity in the triplet state.

Synthesis of Five-Membered Osmacycloallenes and Conversion into Six-Membered Osmacycloallenes

Highly stable five-membered metallacycloallenes were synthesized under mild conditions. Calculations revealed that the incorporation of transition-metal moieties relieves considerable strain and indicates a trend toward ring enlargement in the five-membered metallacycloallenes. Conversion into six-membered metallacycloallenes was confirmed experimentally.