%0 Journal Article %A Berclaz, T. %A Bernardinelli, G. %A Geoffroy, M. %A Rao, G. %A Tancic, Z. %T EPR/ENDOR study of an X-irradiated single crystal of 1-triphenylphosphoranylidene-2-propanone : the role of hydrogen bonds in the trapping of radiogenic radical %J Radiation physics and chemistry %@ 0969-806X %V 56 %N 5-6 %P 539-545 %D 1999 %U http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TVT-3Y9YKSF-4&_user=779890&_handle=W-WA-A-A-AZ-MsSAYZW-UUA-AUZWWWEBCV-WUYUZUZBU-AZ-U&_fmt=summary&_coverDate=11%2F12%2F1999&_rdoc=4&_orig=browse&_srch=%23toc%235543%231999%23999439994%23153590!&_cdi=5543&view=c&_acct=C000043220&_version=1&_urlVersion=0&_userid=779890&md5=636854ba95bc020499b0ed4bd00d9a37 %R 10.1016/S0969-806X(99)00295-9 %U http://archive-ouverte.unige.ch/unige:2736 %X As shown from the crystal structure, the oxygen atom of Ph3P=CH---C(O)CH3 forms both intra and intermolecular hydrogen bonds. X-irradiation of this compounds produces a room-temperature-stable radical which was studied by single crystal EPR/ENDOR spectroscopy. Comparison of the experimental hyperfine couplings with those obtained from ab initio calculations shows that the radical cation Ph3P+---CH=C(OH)CH2 is formed under radiolysis. The principal directions of the hyperfine tensors indicate that, in this process, some of the hydrogen bonds are broken and that the radical undergoes a drastic reorientation around the Ph3P---C bond.