trecenterstvåelektronbindingar

Trecenterstvåelektronbindingar, often abbreviated as 3c-2e bonds, are a type of chemical bond that involves three atoms and two electrons. This contrasts with the more common two-center, two-electron (2c-2e) bonds found in most covalent molecules. In a 3c-2e bond, the two electrons are delocalized and shared among all three participating atoms.

These bonds are particularly significant in electron-deficient compounds where there are not enough valence electrons to form a sufficient number of traditional 2c-2e bonds. A prime example is the bonding in boron hydrides, such as diborane (B2H6). In diborane, two boron atoms and four hydrogen atoms are held together by two 3c-2e bonds, often referred to as "banana bonds." Each of these bonds consists of two electrons spread over three atoms.

The concept of 3c-2e bonding helps explain the stability and structure of compounds that would otherwise be considered unstable or lacking sufficient bonding electrons according to classical Lewis structures. While the electrons are shared by three atoms, the bond order within each 3c-2e bond is effectively less than one, typically around 1/2. This delocalized bonding is crucial for the overall molecular stability. The study of these bonding arrangements has expanded our understanding of chemical bonding beyond the simple pairwise sharing of electrons.