Directed valency

Click on the tip of the equatorial unfilled valence directly across the ring (the valence on C-4). 

Valenz, /. valence, valency, -betatigung, /. valence activity, -einlieit, /. valence unit, valence, -kraft,/. valence (or valency) force, -lehre, /. doctrine of valence, -richtung, /. valence direction, -strich, m. valence line or dash. -8 tufe,/. valence stage. 

Tetrahedral molecules X4, such as P4 and As4. In these compounds each atom has three neighbours with valency lines joining each of the neighbours, so that all the atoms are just saturated. All bonds include angles of 60°, which is much smaller than is to be expected from the valency directions in free atoms. These molecules do not have a minimal energy. 

Figure 19. Secondary valencies directed in space around...

The structure therefore shows the tetrahedral configuration of the copper(I) atom, the coordinated arsenic atoms, and the carbon atoms, and shows that the 3-covalent iodine atom can be regarded as a triangular pyramid—i.e., as if it were lying at one apex of a tetrahedron with its three valencies directed towards the other three apices 36). 

Directed valence Directed valence theory uses two-center bonding orbitals, with hybrid combinations of... 

In the olefin complex the carbon-carbon double bond is believed to be perpendicular to one of the valency directions of the transition metal. The theoretical treatment of Tr-bonding by Chatt and Duncanson (77) furnishes the basic idea underlying the molecular orbital treatment for a variety of complexes between transition elements and unsaturated hydrocarbons. 

In developing the structures of the acids, it was shown that the arrangements of the valence directions in the benzene nucleus were different in different acids, or, in other words, that the substituting group influenced the... 

Sason van t Hoff was a young man when he published his first paper in Dutch in 1874, ... extension of the formulae in use now in chemistry into space... In this paper, he showed that if the valencies (directions of attachments) of carbon... 

The binding curve for the specifically purified antibenzoate antibody (Fig. 2.6) similarly extrapolates to an r value close to 2. However, the relationship between rjc and r is obviously not linear but rather is convex toward the ordinate. This is typical of induced antibody populations and reflects heterogeneity of binding sites with respect to K. Thus, from binding measurements with heterogeneous, purified antibodies one can estimate the valence directly by extrapolation. The visual extrapolation is subject to error if there are substantial amounts of antibody of very low affinity present (discussed below). Since the r/c versus r relationship is not linear, assumptions must be made in order to calculate an average value of K. 

The hemin thus formed has the shape of a flat disk with the iron in the center and its two remaining valencies directed at right angles from the plane of the disk. In the hemoproteins one or both are in all probability bound to the protein component. Under certain conditions, e.g., in acid or alkaline solution, a reversible or irreversible splitting of one or both iron bindings to the protein component may take place. In this connection, however, heme is not always entirely freed from the protein component, but may remain bound by other groups than the iron. 

Valence vector A vector with the magnitude of the bond valence directed from the... 

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