First Stable σ⁰π² Carbene

Key words

stable carbene - P-heterocyclic carbene - rhodium complex - push–pull electronic effects

Significance

Unlike the more commonly found σ²π⁰ singlet and σ¹π¹ triplet carbenes, the σ⁰π² singlet carbene was previously unknown. Here, a rhodium-coordinated, cationic four-membered cyclic diphosphinocarbene is reported, presenting the unique σ⁰π² ground state.

Comment

The rhodium coordinated, four-membered diphosphino-ring successfully realizes a finely balanced combination between the σ-electron delocalization/donation and π-electron negative hyper-conjugation effects, which help stabilize the σ⁰π² singlet state. The new carbene is shown with different reactivity than the traditional carbenes.

Publication History

Article published online:
15 April 2024