Experimental and Computational IR Spectroscopic Studies on the Transmission of Substituent Effects on N–H, C=N, B–N, and B–O Bond Stretching Frequencies in 3,5-Disubstituted-1,2,4,5-Oxadiazaboroles

Abstract

Single and dual substituent correlation analyses are applied to study the transmission of substituent effects on IR stretching frequencies of N–H, C=N, B–N, and B–O bonds in 3,5-disubstituted-4,5-dihydro-1,2,4,5- oxadiazaboroles (1a-1r). For the correlation study σ, F, R, and R^– parameters are used as constants. The substituent effects are estimated based on the results of the statistical analysis. The differences among the regression coefficients are discussed in terms of the relative importance of the substituent field and resonance effects. For a better understanding of the results, density functional theory (DFT) calculations are performed to determine the preferred geometry and to calculate the theoretical stretching frequencies of N–H, C=N, B–N, and B–O bonds.