Application of vibrational spectroscopy to the estimation of electron-donating properties of organometallic groups

It has been established that in compounds of the Ph n MXC 6 H 6 NO 2 type good linear correlations exist between spectral characteristcs and electron-donating properties of XMPh n groups, namely, the integral intensities of v (Ar) and v s (NO 2 ), for each examined class of compounds. The intensities of v s (NO 2 ) have been found to be more sensitive to the electronic effect of substituents and solvation effects. The use of these values has made it possible to determine the σ constants which take into account the direct polar conjugation of XH and XMPh n groups with the reactive center (σ + p , σ + R ). The factors affecting the solvation sensitivity of these values are discussed.