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In coordination chemistry, a coordinate covalent bond, [1] also known as a dative bond, [2] dipolar bond, [1] or coordinate bond [3] is a kind of two-center, two-electron covalent bond in which the two electrons derive from the same atom. The bonding of metal ions to ligands involves this kind of interaction. [4]
Lewis had suggested in 1916 that two atoms are held together in a chemical bond by sharing a pair of electrons. [18] When each atom contributed one electron to the bond, it was called a covalent bond. When both electrons come from one of the atoms, it was called a dative covalent bond or coordinate bond. The distinction is not very clear-cut.
However, these ligands also form dative covalent bonds like the L-type. [2] This type of ligand is not usually used because in certain situations it can be written in terms of L and X. For example, if a Z ligand is accompanied by an L type, it can be written as X 2. Examples of these ligands are Lewis acids, such as BR 3. [3]
For doubly bridging (μ 2-) ligands, two limiting representation are 4-electron and 2-electron bonding interactions. These cases are illustrated in main group chemistry by [Me 2 Al(μ 2-Cl)] 2 and [Me 2 Al(μ 2-Me)] 2. Complicating this analysis is the possibility of metal–metal bonding.
The bond between a water molecule and the metal ion is a dative covalent bond, with the oxygen atom donating both electrons to the bond. Each coordinated water molecule may be attached by hydrogen bonds to other water molecules. The latter are said to reside in the second coordination sphere.
For simple carboxylates, the acetate complexes are illustrative. Most transition metal acetates are mixed ligand complexes. One common example is hydrated nickel acetate, Ni(O 2 CCH 3) 2 (H 2 O) 4, which features intramolecular hydrogen-bonding between the uncoordinated oxygens and the protons of aquo ligands. Stoichiometrically simple ...
As such, the predicted shape and bond angle of sp 3 hybridization is tetrahedral and 109.5°. This is in open agreement with the true bond angle of 104.45°. The difference between the predicted bond angle and the measured bond angle is traditionally explained by the electron repulsion of the two lone pairs occupying two sp 3 hybridized orbitals.
Structure of one part of one stack of the charge-transfer complex between pyrene and 1,3,5-trinitrobenzene. [1]In chemistry, charge-transfer (CT) complex, or electron donor-acceptor complex, describes a type of supramolecular assembly of two or more molecules or ions.