Hydrogen-carbon bonds infrared absorption frequencies

The infrared spectra of a number of hydroxyalkylmetallocenes have been interpreted in terms of hydrogen bonding involving the metal atom. The best example is provided by the epimeric alcohols (XVI and XVII), which exhibit absorption at 3610 and 3561 cm. , respectively, in dilute carbon disulfide solution 23, 24, 59), The low frequency band which, with the absorption near 3600 cm. appears as well in the spectra of acyclic a- and jS-hydroxyalkylferrocenes, has been assigned to the metal-bound hydrogen bond 23, 24, 59, 61),... 

The absorption infrared spectra of ABA (n = 1-9) and nAOBA (n = 3-12) have been measured in the spectral range from 100 to 4000 cm ( 3 cm-1) and in the temperature interval from 100 to 550 K ( 1 K) [57,58,60]. The assignment of the spectral infrared bands to the vibrations of atoms of the dimer ring (Fig. 2) has been made based on calculations of frequencies and shapes of normal coordinates performed for dimers of homologies of carbon acids [292]. Vibrations of the parareplaced benzoic acid and its alkyl radical have been interpreted on the basis of calculations carried out in Refs. 294 and 295, respectively. The maxima recorded at 2900 cm-1 (Voh band), 1692 cm-1 (vc=o band), and 940 cm-1 (p0H band) for all phases of the ABA and AOBA are direct evidence for the connection of molecules ABA and AOBA via hydrogen bonds. 

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