Band Assignments and Structure Elucidation

Band Assignments and Structure Elucidation.— The conjugated A -phospholens can be distinguished from A -phospholens by the low frequency ca. 2225 cm ) of their P—H stretching vibrations. The i.r. and Raman spectra of the chloride (122)... 

Band Assignment and Structural Elucidation.—The change in frequency of v(PH) from 2410 to 1753 cm upon deuteriation confirmed the presence of a PH bond in (121). In contrast to v(OH) of acidic and alcoholic OH groups, v(PH) of the phosphonium salt (121) is at higher wavenumber than v(PH) for primary and secondary phosphines ca. 2300 cm" ), and it is still... 

The vibration bands relative to phosphate groups in the apatite structure differ from the normal modes of the P04 isolated ion, due to distortions of the PO4 tetrahedra in the apatite lattice and vibrational coupling [4]. Therefore, site-group and factor-group analyses were applied [15,16,18,21] to elucidate the vibrational spectra observed (Fig. 5) and band assignments of infrared (IR) and Raman bands have been given (Table 3). 

Usefulness of IR and NMR data in assigning tautomer structure was further validated by structural elucidation of dihydropyrimidine 19 based on Silversmith s data.144 Its structure was assigned as the 1,6-tautomer 19b, based on a reinvestigation of its IR band at 1652 cm-1, similar to the IR spectra of 20b. This was later confirmed by X-ray analysis.23... 

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