Cylindrically symmetrical bond

Formation of a er bonding MO. When the Is orbitals of two hydrogen atoms overlap in phase, they interact constmctively to form a bonding MO. The electron density in the bonding region (between the nuclei) is increased. The result is a cylindrically symmetrical bond, or sigma (o-) bond. 

Sigma (a) bond (Section 1.8A) A cylindrically symmetrical bond that concentrates the electron density on the axis that joins two nuclei. All single bonds are c bonds. 

There is zero probability of finding an electron at a node. Cylindrically symmetrical bonds are called sigma (cr) bonds side-to-side overlap of parallel p orbitals forms a pi (tt) bond. 

The ligand MOs are of two types a MOs, which are cylindrically symmetrical about the metal-ligand bond, and n MOs which are not. The a type of metal-ligand bonding is usually... 

Valence bond theory offers no immediare qualitative explanation since the a bond that is involved is cylindrically symmetrical. A steric argument based on repulsions between hydrogens also fails because on detailed examination of this hypothesis, it is found that the... 

We know from Section 1.5 that cr bonds are cylindrically symmetrical. In other words, the intersection of a plane cutting through a carbon-carbon singlebond orbital looks like a circle. Because of this cjdindrical symmetry rotation is possible around carbon-carbon bonds in open-chain molecules. In ethane, for instance, rotation around the C-C bond occurs freely, constantly changing the spatial relationships between the hydrogens on one carbon and those on the other (Figure 3.5),... 

Pig. 1. Polar graph showing the dependence on and q> of a tetrahedral bond orbital. The value of y> in cross-section is shown the function is cylindrically symmetrical about the midline of this cross-section. 

Ethyne has two jt bonding orbitals at right angles to each other and a resultant jt electron density that is cylindrically symmetric with respect to the internuclear axis. Complexes of ethyne with HF [133], HC1 [134], HBr [135], C1F [66], CI2 [47], BrCl [50], Br2 [92] and IC1 [95] have been characterised by... 

The 327-670 GHz EPR spectra of canthaxanthin radical cation were resolved into two principal components of the g-tensor (Konovalova et al. 1999). Spectral simulations indicated this to be the result of g-anisotropy where gn=2.0032 and gi=2.0023. This type of g-tensor is consistent with the theory for polyacene rc-radical cations (Stone 1964), which states that the difference gxx gyy decreases with increasing chain length. When gxx-gyy approaches zero, the g-tensor becomes cylindrically symmetrical with gxx=gyy=g and gzz=gn. The cylindrical symmetry for the all-trans carotenoids is not surprising because these molecules are long straight chain polyenes. This also demonstrates that the symmetrical unresolved EPR line at 9 GHz is due to a carotenoid Jt-radical cation with electron density distributed throughout the whole chain of double bonds as predicted by RHF-INDO/SP molecular orbital calculations. The lack of temperature... 

The 7i electron density in the triple bond of ethyne is cylindrically symmetric. 

As represents the contraction of the density perpendicular to the bond path, e is >0. For a cylindrically symmetric a bond, the ellipticity will be zero, while it is different from zero for double bonds which have a % contribution. 

A The C-C bond is a a bond and is cylindrically symmetric. There is free rotation about such a bond, so there is only one form of the XH2CCH2X compounds. 

Ib methyl fluoride two electrons with opposed spins are concentrated along the C—F bond. The fluorine atom is, in consequence of correlation, presumably not cylindrically symmetrical about the bond direction, but somewhat hexafoliate. In water and dimethyl ether the two unshared electron pairs of the oxygen atom, despite the effect of correlation, are directed toward two corners of the tetrahedron that has its other two corners determined by the two bonds. 

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