Coordinate covalency term

The hydrated ion [Cu(H20)6]2+ is an example of a complex, a species consisting of a central metal atom or ion to which a number of molecules or ions are attached by coordinate covalent bonds. A coordination compound is an electrically neutral compound in which at least one of the ions present is a complex. However, the terms coordination compound (the overall neutral compound) and complex (one or more of the ions or neutral species present in the compound) are often used interchangeably. Coordination compounds include complexes in which the central metal atom is electrically neutral, such as Ni(CO)4, and ionic compounds, such as K4[Fe(CN)6]. 

KEY TERMS chelating agent sequestrant coordinate covalent bond... 

A bond formed by coordination of two neutral molecules or moieties. lUPAC now favors use of this term over various synonyms, such as coordinate covalent bond. lUPAC (1979) Pure and Appl. Chem. 51, 1725. 

In method (1), each atom brings an electron for the sharing. In method (2), the donor atom (B ) brings both electrons to the marriage with the acceptor atom (A) in this case the covalent bond is termed a coordinate covalent bond. 

Valence bond theory describes the bonding in complexes in terms of two-electron, coordinate covalent bonds resulting from the overlap of filled ligand orbitals with vacant metal hybrid orbitals that point in the direction of the ligands sp (linear), sp3 (tetrahedral), dsp2 (square planar), and d2sp3 or sp3d2 (octahedral). 

One might describe the bonding in CaF2 - which has 8 4 coordination -in terms of covalent bonding in which the F atoms each form four bonds (including three dative bonds) ... 

We shall now focus upon 2D and 3D structures that will be oiganized by dimensionality of architecture and chemical components and draw mineralomimetic analogies. In terms of chemical composition, we shall focus upon purely organic networks, which are typically sustained by hydrogen bonds and stacking interactions, and metal-oiganic structures that are based upon coordinate covalent bonds. 

The Lewis concept of acids and bases (G. N. Lewis, 1923) interprets the combination of acids with bases in terms of the formation of a coordinate covalent bond. A Lewis acid can accept and share a lone pair of electPDns donated by a Lewis base. Because protons readily attach themselves to lone electron pairs, Lewis bases are also Biyinsted bases. Lewis acids, however, include a large number of substances in addition to proton donors for examjjle, metal ions, acidic oxides, or atoms. 

The term is preferred to the obsolescent synonyms coordinate link, coordinate covalence, dative bond, and semipolar bond. 

The autoionization of water (Section 10-5) was described in terms of Bronsted-Lowry theory. In Lewis theory terminology, this is also an acid-base reaction. The acceptance of a proton, H, by a base involves the formation of a coordinate covalent bond. 

Electron Transfer. Neta and coworkers have worked extensively with halogen-substituted methyl peroxyl radicals (X H COO , where X = Cl, Br or F) in aqueous and non-aqueous media, using combinations of solvents in different ratios to change the polarity of the mixture. They describe the mechanism for the reaction of the water-soluble antioxidant Trolox with their peroxyl radicals as H-mediated electron transfer , having determined that the rate of the reaction increases with an increase in solvent polarity. They examined solvent polarity in terms of the dielectric constant of the solvent, e, and solvent basicity, reported as either the coordinate covalency parameter, f, which is a measure of solvent proton-transfer basicity, or the value, which is a measure of solvent hydrogen bond basicity . 

This S—O bond, however, is not strong since addition of RS- to O2 will lead to the formation of a derivative of sulfenic acid, RSOR. Such derivatives are very unstable. Stable S—O bonds are the ones present in the isomeric sulfoxides, RR SO, which are coordinate covalent bonds. In HSAB terms, RSOR is a combination of a soft acid, RS , with a hard base, R O, while sulfoxide is a combination of a soft acid, oxene (the oxygen atom), with a soft base, RSR. ... 

ReaxFF also includes other terms—covalent terms to describe the effect of lone pairs, conjugation, under-coordination, etc. The reader is referred to the original publications for a description of these terms [13, 27][13]. 

It remained for G.N. Lewis (2), M.L. Huggins (3), and their contemporaries to interpret the primary and secondary valences of Werner in terms of the newly emerging electron patterns which were being used to explain "valence." Primary valences were normal covalent bonds (one electron from each bonded atom) and secondary valences were coordinate covalent bonds (two electrons for bond formation supplied by the ligand). The terms Lewis base and Lewis acid entered the literature. The Werner and Lewis-Huggins descriptions of stmcture and bonding were excellent for the metal-ammines, halo complexes of metals, and related species. Classical Werner coordination compounds fit the Wemer-Lewis description, and there were many of such compounds. 

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