ENDOR Study of 14N Hyperfine and Quadrupole Couplings of N2D4 •+ Formed in Deuterated Li(N2H5)SO4 Single Crystal

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 106; no. 11; pp. 2617 - 2622
• Main Authors: Itagaki, Yoshiteru, Sanderud, Audun, Sagstuen, Einar, Lund, Anders
• Format: Journal Article
• Language: English
• Published: American Chemical Society 21.03.2002
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp0125303

X-irradiated Li(N2D5)SO4 single crystals were investigated using EPR and ENDOR spectroscopy. The 14N-ENDOR spectra of the deuterated hydrazine radical cation N2D4 •+ were clearly observed at 240 K. 14N hyperfine (hfc) and nuclear quadrupole (nqc) tensors of the N2D4 •+ cation were determined from angular variation ENDOR measurements in the three orthogonal planes of the crystal. The hfc tensor obtained for the two equivalent 14N atoms is very close to that reported in a N2H5HC2O4 single crystal, and the present results support the previous conclusion that the cation has a planar structure at 240 K. The 14N nqc tensor was estimated using semiempirical methods and also calculated from the field gradients in the LiHzS crystal as evaluated by density functional theory methods. The general agreement with experimental observations further supported the suggested geometrical structure of the N2H4 •+ radical. The 1H and 14N-ENDOR enhancements observed may be due to weakened dipolar interactions between 14N−2D and 1H−2D leading to increased T 1n relaxations of the 14N and residual 1H nuclei of the N2D4 •+ cation (and/or other isotopomers) in the deuterated crystals as compared to those in the Li(N2H5)SO4 crystals.