Isoelectronic

The comparison of the MO diagrams of molecular nitrogen and carbon monoxide shows: The number and configuration of binding electrons of these molecules ...

is identical: The bond order is consequently also identical. The molecules are isoelectronic . The electron deficiency of carbon compared to nitrogen is compensated for by the 4th electron of the 2p orbital in oxygen. This can result in the same binding configuration. ${\displaystyle (\sigma _{s(x)}^{b})^{2}(\sigma _{s}^{*})^{2}(\pi _{y,z}^{b})^{4}(\sigma _{x(s)}^{b-nb})^{2}}$

As isoelectronic refers to two atoms , ions , molecules or formula units when identical electron number, electronic configuration and atomic number possess, although from different elements exist. In the case of connections , this also results in a matching bond geometry.

The physical and chemical properties of isoelectronic compounds often differ considerably. Since the total charge and / or the charge distribution of isoelectronic compounds often differ significantly from one another, properties that are particularly strongly influenced by this are less similar than others that are less influenced by it (cf. isosteria ). Some isoelectronic compounds have e.g. B. very similar qualities as a ligand or Lewis base in complex compounds , see the examples.

Examples:

• O ²⁻ - F ^- - Ne - Na ⁺
• HF - OH ^- - NH ²⁻
• CO - CN ^- - NO ⁺ - N ₂
• CO ₂ - N ₃ ^-

The term "iso-valence electronic" is a little broader . Here only the valence shell has to be structured in an analogous manner and filled with the same number of electrons. These include B. Compounds in which one partner is replaced by the element above or below it in the periodic table .

Examples:

• O ²⁻ - Cl ^- - Ne - K ⁺
• CCl ₄ - SiCl ₄ - AlCl ₄ ^- - PBr ₄ ⁺
• H ₂ SO ₄ - H ₂ S ₂ O ₃ - H ₂ PO ₄ ^-
• [Mo (CO) ₆ ] - [V (CO) ₆ ] ^- - [Fe (CN) ₆ ] ⁴⁻

See also

• Isolobality
• Highly Charged Ion for the emission lines of an isoelectronic series

swell

• Entry on isoelectronic . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.I03276 .

Individual evidence

1. ^ Erwin Riedel, Christoph Janiak: "Riedel - Inorganische Chemie" (8th edition). Publisher: De Gruyter Studium. ISBN 978-3-11-022566-2 . Page 146f.
2. ^ Erwin Riedel / Christoph Janiak: Inorganic Chemistry (8th edition). ISBN 978-3-11-022566-2 .