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Half-bonds

Notice the alternating double and single bonds between the carbon atoms. These are called conjugated bonds, or resonance bonds. The electrons in those bonds are not locked on to one atom—instead they spend their time bouncing from atom to atom. This gives the effect of something in between a double bond and a single bond, more of a one-and-a-half bond. [Pg.108]

The double bond in this molecule is actually a cr-bond plus two half tt-bonds, each half bond consisting of a pair of bonding electrons and one antibonding electron. [Pg.245]

In the nonbonding orbital two electrons are delocalized over the two fluorine atoms and do not contribute to the bonding, which is due only to the two electrons in the bonding orbital. This type of 3c, 4e bond is often denoted by a dashed line, as shown in Figure 2. Each P—F bond is effectively a half-bond, so this description of the bonding is roughly equivalent to the two resonance structures 1 and 2 ... [Pg.228]

Figure 7. (a) Stereo view of comparison of the main chain of the X-ray structure of the HIV-1 protease complex with compound 2 (red) with the main chains of the minimized complex (yellow) and a 20ps average dynamical structure of the same complex of HIV-1 protease (green), (b) Stereoview of the active-site geometry of the crystal structure (in half-bond color) of the HIV-1 protease complexed with the compound 2 (with the indole and phenyl groups shown in red) as revealed by X-ray crystallography. [Pg.327]

Figure 3.32 Overlapping NHOs (left) and bonding NBO (right) for the a.half-bond of singlet Ga2 (R = 2.7444 A). Each NHO is of sp194 hybrid composition (94.7% p character), oriented 40.7° from the line of nuclear centers. (The equivalent (3 half-bond is rotated by 180° about the Ga—Ga axis.)... Figure 3.32 Overlapping NHOs (left) and bonding NBO (right) for the a.half-bond of singlet Ga2 (R = 2.7444 A). Each NHO is of sp194 hybrid composition (94.7% p character), oriented 40.7° from the line of nuclear centers. (The equivalent (3 half-bond is rotated by 180° about the Ga—Ga axis.)...
Figure 3.54 shows the form of two singly occupied spin-NBOs in the vinylamine triplet excited state the 7tCN 1 half-bond of the (3 spin set (Fig. 3.54(a)) and the terminal nc radical orbital of the a spin set (Fig. 3.54(b)). Neither of these orbitals has a true counterpart in the MOs or NBOs of the ground-state molecule. These results emphasize that hyperconjugative reorganization is a strong feature of the excited-state orbitals, and the oversimplified HOMO-LUMO (Koopmans-like)... [Pg.225]

Figure 3.54 Singly occupied spin-NBOs of the lowest triplet 7t 7t+ excited state of vinylamine (X = NH2) (a) The 7TCn half-bond, (3 spin and (b) the ncf radical orbital of the terminal C atom, a spin. Figure 3.54 Singly occupied spin-NBOs of the lowest triplet 7t 7t+ excited state of vinylamine (X = NH2) (a) The 7TCn half-bond, (3 spin and (b) the ncf radical orbital of the terminal C atom, a spin.
Comparison with the corresponding dianion reveals important structural differences. In fact, the triply bridging apical carbonyl is no longer present and one of the bonds of the bridging carbonyl (namely, Fe3-Cl) weakens (becoming half-bonding). This asymmetric disposition of the ligand leads to an inequivalence of all the three Fe-Fe distances. [Pg.425]

This Lewis structure suggests that SO2 contains a single bond and a double bond. However, experimental measurements of bond lengths indicate that the bonds between the S and each O are identical. The two bonds have properties that are somewhere between a single bond and a double bond. In effect, the SO2 molecule contains two one-and-a-half bonds. [Pg.176]

You can see resonance structures for benzene in the following figure. Adjacent carbons in the ring are held together with either single or double covalent bonds, depending on the resonance structure. So in the resonance hybrid structure, each Ccirbon-carbon bond is identical and is like a one-and-a-half bond rather than a single or double bond. [Pg.78]

In a few molecules and crystals it is convenient to describe the interactions between the atoms in terms of the one-electron bond and the three-electron bond. Each of these bbnds is about half as strong as a shared-electron-pair bond each might be described as a half-bond.1 There are also many other molecules and crystals with structures that may be described as involving fractional bonds that result, from the resonance of bonds between two or more positions. Moat of these molecules and crystals have a smaller number of valence electrons than of stable bond orbitals. Substances of this type are called electron-deficient substances. The principal types of electron-deficient substances are discussed in the following sections (and in the next chapter, on metals). [Pg.340]

N5sbO . The observed distance for NO is 1.151 A, somewhat larger than that expected for a 2 J bond it corresponds, when interpreted with use of an equation similar in form to Equation 7-7, to the bond number 2.31. We conclude that the difference in electronegativity of the two atoms decreases the contribution of structure II to such an extent that the three-electron bond is about a one-third bond, rather than a one-half bond. [Pg.344]

The expected half-bond boron-boron distance is twice the singlebond radius 0.81 A (Table 7-18) plus the half-bond correction 0.18 A (Equation 7-7). This value, 1.80 A, agrees well with the experimental value, 1.797 0.015 A. For the other bonds the calculated distance is 1.65 A and the observed value is 1.62 0.92 A. [Pg.365]

The most stable boranes are BioHu and B Ha. In each of these two molecules every boron atom has one nonbridging H attacked, and all (BioHu) or most (B H ) of the boron atoms form five half-bonds (in... [Pg.377]


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See also in sourсe #XX -- [ Pg.9 ]

See also in sourсe #XX -- [ Pg.114 ]




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Bond order Half the number of electrons

Dependence of Half-lives on Chemical Bonding

Hydrogen bonding half-live

Lewis theory half bond

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