How is backbonding treated in the theory of covalent bonding?

1 Answer
anor277
Aug 20, 2017

All covalent bonding is marked by the sharing of electrons between two atoms.

Explanation:

Backbonding is usually invoked in coordination chemistry, where an electron donor, a ligand, binds to, coordinates to a Lewis-acidic metal centre by donating electrons. If the metal is already in a low oxidation state, further coordination MAY not occur, unless there is a mechanism by which the metal can back-donate electron density to the ligand. Ligands such as carbon monoxide are known as #pi-"acids"#, given their ability to accept electron density from a metal centre......

barron.rice.edu

For complexes such as #[CrCO_6]# the #C-O# stretching frequency observed in the IR spectrum is MARKEDLY reduced because the zerovalent metal DONATES electron density to the #pi"*"#, antibonding orbitals of carbon monoxide, which are UNFILLED in #""^(-):C-=O:^+#. This interaction is ANTIBONDING with respect to the #C-O# bond, and thus its stretching frequency is reduced in the IR spectrum with respect to free #CO#; but it IS BONDING with respect to #Cr-C# as it places more electron density between the metal and the binding carbon.

Related questions
See all questions in Bonding
Impact of this question
2312 views around the world
You can reuse this answer
Creative Commons License