Editing Pi backbonding (section)

{{Short description|Form of interaction between two atoms}}

In [[chemistry]], '''pi backbonding''' or '''π backbonding''' is a [[Pi bond|π-bonding]] interaction between a filled (or half filled) [[Atomic orbital|orbital]] of a transition metal atom and a vacant [[Atomic orbital|orbital]] on an adjacent ion or molecule.<ref>{{Cite book |last1=Miessler |first1=Gary L. |title=Inorganic chemistry |last2=Tarr |first2=Donald A. |date=1999 |publisher=Prentice Hall |isbn=978-0-13-841891-5 |edition=2nd |location=Upper Saddle River, N.J |pages=338}}</ref><ref>{{Cite book |title=Advanced inorganic chemistry |date=1999 |publisher=Wiley |isbn=978-0-471-19957-1 |editor-last=Cotton |editor-first=Frank Albert |edition=6th |location=New York |editor-last2=Wilkinson |editor-first2=Geoffrey |editor-last3=Murillo |editor-first3=Carlos A.}}</ref> In this type of interaction, electrons from the metal are used to bond to the [[ligand]], which dissipates excess negative [[Electric charge|charge]] and stabilizes the metal. It is common in [[transition metal]]s with low oxidation states that have ligands such as [[Metal carbonyl|carbon monoxide]], [[olefins]], or [[phosphine]]s. The [[ligand]]s involved in π backbonding can be broken into three groups: [[Metal carbonyl|carbonyls]] and nitrogen analogs, [[alkene]]s and [[alkyne]]s, and [[phosphines]]. Compounds where π backbonding is prominent include [[Nickel carbonyl|Ni(CO)<sub>4</sub>]], [[Zeise's salt]], and [[Abiological nitrogen fixation using homogeneous catalysts|molybdenum and iron dinitrogen complexes]].