Coordinate covalent bond


Coordinate covalent bond

[
ammonium ion] A coordinate covalent bond (formerly also known as dative bond [GoldBookRef | file = D01523 | title = dative bond] ) is a description of covalent bonding between two atoms in which both electrons shared in the bond come from the same atom. The distinction from ordinary covalent bonding is artificial, but the terminology is popular in textbooks, especially those describing coordination compounds. Once the bonds have been formed using this, its strength and description is no different from that of other polar covalent bonds.

Coordinate covalent bonds occur when a Lewis base (an electron donor or giver) donates a pair of electrons to a Lewis acid (an electron acceptor) to give a so-called "adduct". The process of forming a dative bond is called "coordination". The electron donor acquires a positive formal charge, while the electron acceptor acquires a negative formal charge.

Examples

Classically, any compound that contains a lone pair of electrons is capable of forming a coordinate bond. The bonding in diverse chemical compounds can be described as coordinate covalent bonding.
*Carbon monoxide (CO) can be viewed as containing one coordinate bond and two "normal" covalent bonds between the carbon atom and the oxygen atom. This highly unusual description illustrates the flexibility of this bonding description. Thus in CO, carbon is the electron acceptor and oxygen is the electron donor.
*beryllium dichloride (BeCl2) is described as electron deficient in the sense that the triatomic species (which does exist in the gas phase) features Be centers with four valence electrons. When treated with excess chloride, the Be2+ ion binds four chloride ions to form tetrachloroberyllate anion, BeCl42-, wherein all ions achieve the octet configuration of electrons.

Coordination compounds

Coordinate bonding is popularly used to describe coordination complexes, especially involving metal ions. In such complexes, several Lewis bases "donate" their "free" pairs of electrons to an otherwise naked metal cation, which acts as a Lewis acid and "accepts" the electrons. Coordinate bonds form and the resulting compound is called a "coordination complex", and the electron donors are called ligands. A more useful description of bonding in coordination compounds is provided by Ligand Field Theory, which embraces molecular orbitals as a description of bonding in such polyatomic compounds.

Many chemical compounds can serve as ligands, often these contain oxygen, sulfur, nitrogen, and halide ions. The most common ligand is water (H2O), which forms coordination complexes with metal ions (like the hexaaquacopper(II) ion, [Cu(H2O)6] 2+). Ammonia (NH3) is also a common ligand, as well as anions, especially fluoride (F), chloride (Cl), and cyanide (CN).

See also

* Sigma bond
* Pi bond
* Delta bond

References

External links

* [http://www.chemguide.co.uk/atoms/bonding/dative.html Chemguide]


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Look at other dictionaries:

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  • covalent bond — n. the chemical bond formed between two atoms when they share electrons in pairs, so that each atom provides half the electrons: see IONIC BOND, COORDINATE BOND …   English World dictionary

  • covalent bond — noun a chemical bond that involves sharing a pair of electrons between atoms in a molecule • Hypernyms: ↑chemical bond, ↑bond • Hyponyms: ↑double bond, ↑coordinate bond, ↑dative bond * * * noun : a nonionic chemical bond formed …   Useful english dictionary

  • covalent bond — Chem. the bond formed by the sharing of a pair of electrons by two atoms. [1960 65] * * * Force holding atoms in a molecule together as a specific, separate entity (as opposed to, e.g., colloidal aggregates; see bonding). In covalent bonds, two… …   Universalium

  • coordinate bond — n. the type of covalent bond in which the shared pair of electrons is supplied by only one of the atoms; dative bond …   English World dictionary

  • bond — In chemistry, the force holding two neighboring atoms in place and resisting their separation; a b. is electrovalent if it consists of the attraction between oppositely charged groups, or covalent if it results from the sharing of one, two, or… …   Medical dictionary

  • coordinate bond — noun a covalent bond in which both electrons are provided by one of the atoms • Syn: ↑dative bond • Hypernyms: ↑covalent bond * * * noun or coordinate covalence : a covalent bond typical of coordination complexes that is held to consist of a pair …   Useful english dictionary

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  • coordinate — (also co ordinate) verb kəʊ ɔ:dɪneɪt 1》 bring the different elements of (a complex activity or organization) into an efficient relationship.     ↘negotiate with others in order to work together effectively. 2》 match or harmonize attractively. 3》… …   English new terms dictionary


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