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Z. Naturforsch. 2012,
67b, 1305 – 1313
doi:10.5560/ZNB.2012-0069
DFT and MP2 Study of the Molecular Structure and Vibrational Spectra of the Anticancer Agent Cyclophosphamide
Department of Chemistry, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran 31261, Saudi Arabia
Reprint requests to W. Förner. Tel.: 966 3 860 3553. Fax: 966 3 860 4277. E-mail:
forner@kfupm.edu.sa
Received March 7, 2012; in revised form: April 22, 2012 / published online November 30, 2012
The possible conformations in the most stable structure of cyclophosphamide were investigated at the DFT-B3LYP and MP2/6-311G** levels of calculation. The axial structure is calculated to be lower in energy than the equatorial form of cyclophosphamide by 5 (MP2) to 6 (DFT) kcal mol−1 because of a very weak anomeric effect and weak conjugation. Further it is the same structure as the one found in the X-ray investigations both of the hydrate and of the anhydrous form. The computed DFT vibrational frequencies of the axial structure were used to analyze the infrared and Raman spectra using normal-coordinate calculations to provide reliable assignments to the normal modes of the molecule.
Key words: Conformational Structure, Vibrational Spectra, Cyclophosphamide, N,N-Bis(2-chloroethyl)-1,3,2-oxazaphosphinan-2-amine-2-oxide, Anticancer Agent
Supporting Material: