Bond-stretching frequencies

Another example of a stereoelectronic effect is observed in amines. Amines in which a C—H bond is oriented antiperiplanar to the nitrogen lone pair show a shift in the C—H bond stretching frequency that corresponds to a weakening of the bond by about... 

Double-Bond Stretching Frequencies of Enamines and Their Perchlorate Salts... 

No systematic IR spectroscopic studies have been reported. The value for the C-C double-bond stretching frequency of the enol ether structure in 2,7-dimethyloxepin is 1660cm-1.12... 

Only limited IR spectroscopic data for (benzo)thiepins have been reported. The C —C double bond stretching frequency in 2,7-di-rm-butyl-4,5-dimethylthiepin is observed at 1620 cm-1 with weak intensity.13 Characteristic strong intensities are found for the S —O vibrations in sulfoxide (e.g., 1040 cm-1 for 5-methoxy-4-phenyl-l-benzothiepin-3(2//)-one 1-oxide14) and sulfone (e.g., 1120 and 1300 cm-1 for thiepin 1,1-dioxide15) derivatives. 

Bond-stretching frequencies quoted here are from ref. 1 or standard compilations of infrared data. 

The increase of the exocyclic C—C bond stretching frequency from 1208 cm in toluene to 1264 cm in the benzyl radical and the simultaneous decrease of the C—C ring bond stretching frequencies (from 1494 and 1460cm to 1469 and 1446cm , respectively) result from electron density delocalization in the benzyl system. Furthermore, the force constant value for the C—C bond in the C6H5CH2 radical (5.5 X 10 N m ) is between the values for the ordinary C—C bond (4.5 x 10 N m ) and the double C=C bond (9.0 X 10 N m ) and is close to the corresponding force constant in the allyl radical (5.8 x 10 N m ). 

S. Jarmelo, N. Maiti, V. Anderson, P. R. Carey, and R. Fausto, Ca H bond stretching frequency in alcohols as a probe of hydrogen bonding strength A combined vibrational spectroscopic and theoretical study of n [1 Djpropanol. J. Phys. Chem. A 109, 2069 2077 (2005). 

Similar to the TGA experiments, in situ Infrared Spectroscopy has been used to follow the amide bond stretching frequencies while heating under various atmospheres. ° These experiments (see Fig. 7.2) suggest that dendrimer removal requires relatively forcing conditions to maximize CO adsorption on supported Pt catalysts prepared from A variety of activation conditions have been... 

Bond length vs. bond stretching frequency A good linear relationship ha been establi ed between the S=0 bond length (r) and S=0 bond stretching frequency (v) in the XSO2Y sulphone series ... 

Table 1. Calculated and observed values for the temperature dependence of OH hydrogen bonded stretching frequencies of alcohols...

The triple-bond stretching frequency (1735 cm 1) is also closer to that of the cyclohexyne complex (1721 cm 1) than to that of the corresponding cycloheptyne (1770 cm-1 ).2... 

In some cases where it is difficult to measure bond energy we make use of bond length or bond stretching frequency for comparing the bond strengths. 

Bond stretching frequency (measured by vibrational spectroscopy such IR spectroscopy, etc.) is related to stretching force constant and increases with increase in bond strengths. This study is quite useful for transition metal carbonyls. 

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