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cis-1,2-disub. alkenes 1660 medium trans-1,2-disub. alkenes 1675 medium trisub., tetrasub. alkenes 1670 weak conjugated C═C dienes 1600 strong 1650 strong with benzene ring 1625 strong with C═O 1600 strong C═C (both sp 2) any 1640–1680 medium aromatic C═C any 1450 weak to strong (usually 3 or 4) 1500 1580 1600 C≡C terminal alkynes
alkene (unsaturated) vs alkane (saturated) alkyne (unsaturated) vs alkane (saturated) arene (unsaturated) vs cycloalkane (saturated) For organic compounds containing heteroatoms (other than C and H), the list of unsaturated groups is long but some common types are: carbonyl, e.g. ketones, aldehydes, esters, carboxylic acids (unsaturated) vs ...
The weakening of the C–O bond is indicated by a decrease in the wavenumber of the ν CO band(s) from that for free CO (2143 cm −1), for example to 2060 cm −1 in Ni(CO) 4 and 1981 cm −1 in Cr(CO) 6, and 1790 cm −1 in the anion [Fe(CO) 4] 2−. [3] For this reason, IR spectroscopy is an important diagnostic technique in metal–carbonyl ...
The ionization of alkanes weakens the C-C bond, ultimately resulting in the decomposition. [7] As the bond breaks, a charged, even electron species (R+) and a neutral radical species (R•) are generated. Highly substituted carbocations are more stable than the nonsubstituted ones. An example is depicted below. Sigma bond cleavage of an alkane.
The barrier for the rotation of the alkene about the M-centroid vector is a measure of the strength of the M-alkene pi-bond. Low symmetry complexes are suitable for analysis of these rotational barriers associated with the metal-ethene bond.In Cp Rh(C 2 H 4 )(C 2 F 4 ), the ethene ligand is observed to rotate with a barrier near 12 kcal/mol but ...
Trans-alkenes are about 1 kcal/mol more stable than cis-alkenes. An example of this effect is cis- vs trans-2-butene. The difference is attributed to unfavorable non-bonded interactions in the cis isomer. This effects helps to explain the formation of trans-fats in food processing. In some cases, the isomerization can be reversed using UV-light.
Two-dimensional infrared spectroscopy (2D IR) is a nonlinear infrared spectroscopy technique that has the ability to correlate vibrational modes in condensed-phase systems. This technique provides information beyond linear infrared spectra, by spreading the vibrational information along multiple axes, yielding a frequency correlation spectrum.
The method of Fourier-transform spectroscopy can also be used for absorption spectroscopy. The primary example is "FTIR Spectroscopy", a common technique in chemistry. In general, the goal of absorption spectroscopy is to measure how well a sample absorbs or transmits light at each different wavelength.