Three-center four-electron bond

<p>The 3-center 4-electron (3c–4e) bond is a model used to explain bonding in certain <a href="/facts/Hypervalent_molecule/goPjlm9W">hypervalent molecules</a> such as tetratomic and hexatomic <a href="/facts/Interhalogen/TBED2c9B">interhalogen</a> compounds, <a href="/facts/Sulfur_tetrafluoride/jJYpjeSQ">sulfur tetrafluoride</a>, the <a href="/facts/Xenon_fluorides/ar9c5oBu">xenon fluorides</a>, and the <a href="/facts/Bifluoride/dXHfqCLd">bifluoride</a> ion. It is also known as the Pimentel–Rundle three-center model after the work published by  <a href="/facts/George_C._Pimentel/dyQsTbas">George C. Pimentel</a> in 1951, which built on concepts developed earlier by <a href="/facts/Robert_E._Rundle/YJnrrRmM">Robert E. Rundle</a> for electron-deficient bonding. An extended version of this model is used to describe the whole class of <a href="/facts/Hypervalent_molecules/goPjlm9W">hypervalent molecules</a> such as <a href="/facts/Phosphorus_pentafluoride/VbqstNnq">phosphorus pentafluoride</a> and <a href="/facts/Sulfur_hexafluoride/jeee0PJ8">sulfur hexafluoride</a> as well as multi-center π-bonding such as <a href="/facts/Ozone/o0E5gn2p">ozone</a> and <a href="/facts/Sulfur_trioxide/Ijvm08Lq">sulfur trioxide</a>.
</p><p>There are also molecules such as <a href="/facts/Diborane/k7egwbPf">diborane</a> (B2H6) and <a href="/facts/Dialane/fFFAXYVX">dialane</a> (Al2H6) which have <a href="/facts/Three-center_two-electron_bond/1etgQjYh">three-center two-electron</a> (3c–2e) bonds.
</p>

Three-center four-electron bond open-in-new

Three-center four-electron bond