Dipole moments table

BOND AND GROUP DIPOLE MOMENTS Table 4.12 Bond Dipole Moments... 

Chromatographic Behaviour of log P = 3 Compounds in Aqueous Dimethylform-amide (DMF). DMF is a solvent with a strong dipole moment (Table 4.2). The same log A values in 50% aqueous DMF can be obtained at a concentration of 26% aqueous acetonitrile for ROH, 44% aqueous acetonitrile for PAH, 37% for RB, and 36% aqueous acetonitrile for ROB. When eluents with equivalent Po, Xe, Xd, or Xn values in 50% DMF were selected, different log A values were predicted in all three cases. 

Atomic charges on the guest molecules were obtained from first principles Hartree-Fock calculations, fitting the electrostatic potential surface (EPS), then scaled up or down in order to reproduce the experimental dipole moments. Table 2 gives partial charges of typical molecules considered in our work. 

Bond lengths and angles, dipole moments (Table 2, Section 4.01.3.2) and 14N nuclear coupling have been determined and the 14N hyperfine structure has been analyzed for several 1,3,4-oxadiazoles (74PMH(6)53). Observed 44N quadrupole coupling constants have been compared with values obtained from microwave spectra (74JCP(6l)l494). 

Microwave spectroscopy allows the determination of precise bond lengths and angles, conformations, and dipole moments. Table 4 summarizes some molecular geometries deduced from microwave spectra. A disadvantage is that measurements have to be made in the gas phase and studies are limited to relatively small volatile molecules. 

Triazoles. Theoretical studies on a number of derivatives agree that the 177-structure 251 for 1,2,4-triazoles is more stable than the 477-structure 252. The tautomer 251 (R1 = R2 = CH2OMe) was calculated to be more stable than tautomer 252 (R1 = R2 = CH2OMe) by 4.32 kcal mol-1 <2001JHC1387>. In spite of tautomers 252 (R1 = R2 = H) having a much larger dipole moment (Table 3), the 177-tautomers 251 also dominate solution chemistry . 

The comparison of the results with the mutual solubilities of solute and modifier at standard conditions (table 2) and with the standard dipole moments (table 2, 3) proves, that there is no correlation and therefore suitable modifiers must be found empirically. Chemical interactions dominate strongly, so that there is no possibility to correlate the influence of dipole moments with solubility. 

Dimethylformamide and related solvents, such as dimethyl sulphoxide, have high Trouton constants and high dipole moments (Table 1, and... 

In the calculation of the first excited singlet-state dipole moments, the a moment was assumed to be the same as in the ground state and only changes of the it moment were considered. The authors also found a relatively good agreement between the calculated excited-state dipole moments and the average values of the experimental excited-state dipole moments (Table 5) [17]. For comparison, another set of calculated excited-state dipole moments is presented in Table 5 [25,91,92]. 

The dipolar property of calicenes is clearly shown by their large dipole moments (Table 1). ... 

Having set up various levels of computational method, they should then be applied extensively to molecules that are well-characterized experimentally so that the performances of the methods can be documented. In this section we present the results of some such studies for electric dipole moments. Table 2 contains results for electric dipole moments calculated at the STO-3G, 4-31G, and 6-31G levels together with the corresponding experimental data. 

The difference between the chemical behaviour of the substitution products of benzene and the corresponding aliphatic derivatives are well known and are reflected in the values of their dipole moments Table XCVI). In chlorobenzene, in addition to the bond resonance structures, I and II, there are three additional structures Illy IV and V contributing to the molecular resonance and the dipole moment is lowered in comparison with the alkyl halides. 

Since cw-dichloroethylene is a polar molecule but fran -dichloroethylene is not, they can readily be distinguished by a dipole moment measurement. Additionally, as we will see in the next chapter, the strength of intermolecular forces is partially determined by whether molecules possess a dipole moment. Table 10.3 lists the dipole moments of several polar molecules. 

The zirconium tetrahalides react with esters to form ZrX4 2 ester adducts (302, 303, 330, 407-410, 412) in which, coordination number six is attained. On the basis of dipole moments (Table XIII), it is concluded that the adducts have the cis structure. This has been supported, at least in the case of ZrCl4 2011300 0 02115, by the infrared spectrum (330). Oryoscopic studies in benzene solution of the 2 1 adducts of zirconium tetrachloride and ethyl formate, ethyl acetate, and ethyl butryrate show that these complexes tend to decompose to the 1 1 species, the extent of dissociation increasing with the number of carbon atoms in the acid radical. The estimated dissociation constant is about 5 x 10", whereas for the ethyl acetate adduct of zirconium tetrabromide it is only 2 X 10". The approximate dissociation constant of the complex zirconium tetraiodide 2 ethyl acetate is 3.5 x 10". The 1 1 species were synthesized by direct reaction in benzene with strictly stoichiometric ratios of the reactants. Oryoscopic determination of molecular weights of the 1 1 complexes indicate that these complexes generally... 

One of the earliest physical methods employed in the study of heteroaromatic systems was the determination of dipole moments. Table 7 lists the dipole moments of a number of simple derivatives in addition to those reported in CHEC-I. The experimental values for the furan derivatives are those utilized in conformational analysis and discussed in Section 2.05.3. For hydrofuran derivatives the dipole moments reported are those determined from microwave spectra (Stark effect) for the ground state of the ring-puckering mode. 

Cis-trans isomers of alkenes (Section 1.13B) have different physical properties. They have different melting points and boiling points, and often cis—trans isomers differ markedly in the magnitude of their dipole moments. Table 2.2 summarizes some of the physical... 

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