Covalent bonding dative

Problem 18.3 Rationalize the coordination geometries and N-I bond distances in solid NI3 NH3 in terms of covalent bonds, dative bonds and bonds of 50% covalent and 50% dative character. 

Coordinate Covalent Bond n A covalent bond in which both shared electrons appear to have been contributed by one atom. (2) coordinate link, coordinate covalent bond, dative bond, semipolar bond, or dipolar 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 such a bond has been formed, its strength and description is no different from that of other polar covalent bonds. An example of a dipolar bond in the ammonium ion. 

The HF wave funetion eontains equal amounts of ionie and eovalent eontributions (Section 4.3), For covalently bonded systems, like H2O, the HF wave funetion is too ionie, and the effect of electron correlation is to increase the covalent contribution. Since the ionic dissociation limit is higher in energy than the covalent, the effect is that the equiUbrium bond length increases when correlation methods are used. For dative bonds, such as metal-ligand compounds, the situation is reversed. In this case the HF wave function dissociates correctly, and bond lengths are normally too long. Inclusion of... 

With eight outer electrons in the formally neutral atom, iron needs to acquire an electron to achieve covalence. Often the ninth electron is obtained from a carbonyl group forming a dative single covalent bond, Fe —CO+. The Fe(CO)3 group then involves five of the nine bonds formed by the iron atom, the bond number of the iron-carbonyl bonds being 1.67, and the iron atom forms four other bonds. If the added electron... 

IR spectroscopy of adsorbed carbon monoxide has been used extensively to characterize the diluted, reduced Cr/silica system [48-54,60,76,77]. CO is an excellent probe molecule for Cr(ll) sites because its interaction is normally rather strong. The interaction of CO with a transition metal ion can be separated into electrostatic, covalent a-dative, and 7r-back donation contributions. The first two cause a blue shift of the vco (with respect to that of the molecule in the gas phase, 2143 cm ), while the last causes a red shift [83-89]. From a measurement of the vco of a given Cr(II) carbonyl complex, information is thus obtained on the nature of the Cr(II)- CO bond. 

Thiol-containing molecules can interact with metal ions and metal surfaces to form dative bonds. Dative bonds also are known as coordinate covalent bonds. They differ from normal... 

Monodentate (monometallic monoconnective) phosphor-1,1-dithiolato ligands are rare. Bidentate (monometallic biconnective) form chelate rings and three sub-types can be distinguished according to the degree of asymmetry (Scheme 2). The most asymmetric type (anisobidentate) occurs when a covalent bond is associated with a secondary bond this takes place mostly in main-group metal complexes. The second type is rare and is the result of the association between a covalent and a dative coordinate bond. The symmetric bidentate bonding (isobidentate) is found mainly in transition metal complexes. 

A dative covalent bond, or co-ordinate bond, is a covalent bond in which both of the shared pair of electrons come from the same atom. 

Examples The following compounds and species are examples of dative covalent bonding. 

The water molecules are bonded to the central Mn2+ cation via dative covalent bonds from the lone pair on the oxygen atom into empty orbitals in the metal ion. 

In general, the -dependent variations of natural atomic charges in dative bonds are significantly larger than those in covalent bonds. Indeed, the Q (R) variations in dative bonds resemble those in ionic bonds (cf. Fig. 2.9), to which they are evidently related by similarities in donor-acceptor character. The strong AQ /AR dependence tends to be associated with enhanced infrared vibrational intensity and other spectroscopic signatures characteristic of ionic bonding. 

Owing to their dative character, the 0 XH3 bonds of group 15 oxides differ rather remarkably from ordinary covalent bonds involving the same elements. For example, a normal ono bond (e.g., in hydroxylamine, HONH2) would be estimated from Eq. (3.76) to have /no = —0.17, polarized toward the more electronegative O. However, the dative ctn o NBO of 0 NH3... 

Thus, (4.9a) gives the general condition for an idealized covalently bonded closed-shell Lewis-like duodectet structure (4.9b) with no formal charge on the central metal atom. (The more general conditions for coordinative [dative] ligands and other departures from the idealized Lewis-like formula will be discussed below.)... 

A coordinate covalent bond, also known as a dative bond, is a bond in which both electrons are furnished by one atom. 

In this molecule, the aluminium receives a pair of electrons from the nitrogen atom. The nitrogen atom is referred to as a donor atom and the aluminium as an acceptor atom. Once the bond is formed it is identical to the covalent bond of previous examples it differs only in its origin. It is called a co-ordinate or dative bond, and can be... 

The original concepts of metal-ligand bonding were essentially related to the dative covalent bond the development of organometallic chemistry has revealed a further way in which ligands can supply more than one electron pair to a central atom. This is exemplified by the classical cases of bis(benzene)chromium and bis(cyclopentadienyl)iron, trivial name ferrocene. These molecules are characterised by the bonding of a formally unsaturated system (in the organic chemistry sense, but expanded to include aromatic systems) to a central atom, usually a metal atom. 

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