Coordinative valency

While it is possible to solve the vibrational problem using any one of a number of coordinate systems (Cartesian coordinates, spherical polar coordinates, valence coordinates, etc.), it is often most convenient to employ some type of valence... 

In the mathematical theory of networks valence is defined as the number of links terminating at a node, and it was in this sense that the term was introduced into chemistry. However, chemists were later forced to distinguish between a chemical valence (bonding power) and a coordinative valence (number of bonds). They chose to keep the term valence for the chemical valence and introduced the term coordination number for the coordinative valence. This book follows the chemical convention. The term valence is always used in the sense of bonding power unless otherwise stated, and coordination number is used to indicate the number of bonds. 

Topic Coordination valence, Sidgwick, The Electronic Theory of Valency, (1929). 

COORDINATION COMPOUNDS. One of a number of types of complex compounds, usually derived by addition from simpler inorganic substances. Coordination compounds are essentially compounds to which atoms or groups have been added beyond the number possible on the basis of electrovalent linkages, or the usual covalent linkages, to which each of the two atoms linked donates one electron (o Form the duplet. The coordinate groups are linked to the atoms of the compound usually by coordinate valences, in which both the electrons in the bond are furnished by the linked atom of the coordinated group. The amines and complex cyanides are representative of coordination compounds. 

Th-6NH3]Cl4 nNH3 (c). Chauvenet1-2 measured the heats of solution in aqueous HC1 of these coordination valence ammines with n=0, 1, 6, and 12. 

S(VI) represents the six-coordinated valence state of sulfur, which is considered to have lost its 3s and 3p electrons, making six equivalent sp3d2-hybridized orbitals available for accepting lone pairs contributed by the fluorine atoms. 

Although Werner s new chemical concept was developed in 1892 when he was only 26 years old and a Privat-Dozent at the Zurich Polytechnikum, general acceptance did not come until 1911. That year was probably the high point of Werner s career because it was then he resolved the racemic molecules of the 1,2-chloroammine bis (diethylenediamine) cobalt (III) salts. This discovery shook the chemical theory of the time. With this he proved the octahedral formula of a metal compound with 6-coordinate valency, for only this arrangement explained optical symmetry which he had proposed many years before. 

On such a concept, the adsorbed olefin should acquire the electronic configuration of a trivalent positive C atom in the Ph2C+ group, which was presumed to possess the spectrum of a carbonium ions, situated in the range of 400 mp. More exactly, it has been admitted (92) that the electronic configuration produced in the olefin by a coordinative valency bond with the electron-pair acceptor (Lewis) site in silica-alumina, viz.. 

The same process can be achieved by ligand exchange, if ligands of different coordinating valences are used and the concentrations are changed as needed. 

EPR Electron paramagnetic resonance spectroscopy Stmctural and electronic properties of transition metal atoms coordination, valence state, and organic radicals... 

Following Werner, the number of coordinating atoms around the central atom is called the coordination number of the central atom. This term is also used by ciystallographers (Chap. 6). However, the latter use it to describe a particular structure, whereas Werner used it more as a valency. A better term for this purpose would be coordinate valency . 

Note that the correct relation between coordinate valency and Werner s auxiliary or secondary valency (p. 468, col. 1, para. 3 up) is secondary valency = coordinate valency - primary valency used in coordination. ... 

Coordinates, valence force, 174 Coordinate transformation (see Transformation of coordinates)... 

The dissolution of nylon 6 in methanolic Ca02 is also exjdained by formation of a strong bond between nylon and the methanol-CaClj complex Infrared spectra suggest that Ca with the coordination number 6 forms a complex with alcohol molecules, able to solvate the carbonyl group of nylon by one coordination valency (Fig. 16). The dissolving power of alcohdic solutions of other salts was also discussed from the viewpoint of complex formation ... 

By using the optical basicity Ath of cations in their appropriate coordination, valence, and spin, it is possible to calculate the theoretical optical basicity of mixed oxides, oxysalts, or of any oxygen-containing sohd, if the stoichiometry is known. Given a M oxide or mixture, Au, is calculated by the linear combination of stoichiometry x,, valence and A, of the / cations (n = oxygen stoichiometry), according to ... 

---