Conformational, IR, NMR, and EPR analysis of ifosfamide by density functional theory calculation

The optimized molecular structure, vibrational frequencies, H-1 and C-13 NMR chemical shifts, and EPR hyperfine splittings of 3-(2-chloroethyl)-2-[(2-chloroethyl) amino] tetrahydro-2H-1,3,2-oxazaphosphorine-2-oxide (ifosfamide) have been investigated using density functional theory (B3LYP) method with 6-31+G(d, p) basis set for the first time. The calculated optimized geometric parameters (bond lengths and bond angles), vibrational frequencies, NMR chemical shifts, and EPR hyperfine splittings were seen to be in a well agreement with the corresponding experimental data. The experimentalEPRspectrumof themoleculewas recorded after c-irradiation. From the comparison of the calculated and experimental results the formed radical was attributed to a carbon atom-centered radical occurred upon the loss of a chlorine atom due to breakage of the weak C-Cl bonds. So we mentioned that the free electron is transferred to a carbon atom through intramolecular rearrangement while the molecular charge changes to neutral situation, giving NHC alpha H2C beta H2 radical.