Hybridization ratio

The dipole moment of tributylpliosphine varies from 1.49 to 2.4 D according to the solvent used. Inductive effects in phosphines have been estimated by comparing the calculated and observed dipole moments, and the apparent dipole moment due to the lone electron pair on phosphorus has been estimated. A method of calculating the hybridization of the phosphorus atom in terms of bond angles is suggested which leads to a linear relationship between hybridization ratio and lone electron pair moment. The difference between experimental and calculated dipole moments for para-substitued arylphosphines, phosphine sulphides, and phosphinimines has been used to estimate mesomeric transfer of electrons to phosphorus. 

For reasonable values of the hybridization ratio, b/a up to about 0.5, fj and fV can differ by only a few degrees and this kind of hybrid cannot explain the matrix axis non-coincidence. Following the same reasoning with x and y interchanged, exactly the same conclusions can be reached for hybrid 2. Flybrids 11 and 12 are ... 

Information concerning the geometry of the molecule can be obtained from the hybridization ratio y = (h/c. Coulson (7) has shown that for spn type hybridization of the atomic orbital on the central atom the bond angle is related to the hybridization ratio. In a molecule wnth C2 symmetry, such as NO2, the bond angle is given by... 

The ratios in the hybrid rocks are calculated for a few hybrid ratios, which is much... 

Coulson and Moffitt23 established a bent bond model of 1 by elaborating ideas first proposed by Forster24. They determined sp" (CC) and sp" (CH) hybrid orbitals with optimal hybridization ratios n and m to describe bonding in 1. Calculations showed that, for 1, the p-character of the CC hybrid orbitals has to be increased from sp3 to sp4 while the s-... 

The results of the Coulson-Moffitt model have been verified many times using different energy minimization criteria for obtaining the best hybridization ratios (n and m) and determining angles between bent bond orbitals. Some results are summarized in Table i7-23-31-45- 7... 

Conventional strain energies (CSE) in kcal mol1 from HF/6-31G(d) calculations. Hybridization ratios n and m, overlap S, and interbond population values from a configuration analysis47. 

The basis set used is Dunning s cc-pVDZ [16]. The CASSCF wave function was obtained with CAS(4,4). The geometries of the equilibrium and TS structures were determined with this basis set and active space. The orbitals were then localized in the active orbital space. The orbitals were transformed so as to have maximum overlap with two carbon sp2 orbitals and hydrogen Is orbitals. The sp1 orbitals were used with the fixed hybridization ratio of 2s to 2p orbitals (1 2) and with a fixed angle of 120° relative to the CO axis... 

As shown the hybridization ratio need no longer be the same for all bonds with dissimilar substituents. 

The decomposition of the As coupling into isotropic and anisotropic constants leads to arsenic 4s and 4p spin densities equal to 0.06 and 0.75, respectively. From the resulting hybridization ratio X, close to 10.8, the out-of-plane angle can be calculated by using the Coulson formula and by assuming a symmetry (see Figure 2). The value of C (11°)... 

TABLE 6. Arsenic spin densities and hybridization ratio for some arsonyl and oxygen containing arsoranyl radicals... 

HO)2AsO have also been observed. All these arsonyl-type radicals are pyramidal with a hybridization ratio = cl/c whieh lies between 5 and 6.3. As shown in Table 6, these values differentiate them clearly from the trigonal bipyramid structure observed for some oxygen-containing arsoranyl radicals (see Section IV.B). 

TABLE 9. As hyperfine couplings, spin densities and hybridization ratio for PhjAsY" (Y = Cl, Br)... 

There is another area in which the all- or quasi all-electrons methods enable us to go much deeper than the previous approximations, namely the field of the electronic distribution. Thus, both it and o populations are now directly attainable as well as hybridization ratios, which had previously to be assumed, both in the simple representation of the o bonds and in the parameters of the it electron theory 12-14>. 

Table VI. "Hybridization ratios in oxygen and nitrogen by different methods...

This explains readily the nonlinear NHD. In contrast, the hybridization on carbon in the CBr4 nIn series is affected in a very similar manner by I or Br substituents. In particular, the hybridization ratio of the C-I bond changes very little with increasing n (Figure 7). In consequence, a linear NHD arises, corresponding to essentially additive contributions from the halogen... 

Figure 7. Average NPA p/s hybridization ratio [97] on carbon and corresponding NPA-NLMO hybridization ratio [98] of C-I bonds in the CUt.Jn and CBr4.oIn series.

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