TY - JOUR
T1 - Gas-phase reactions between urea and Ca2-
T2 - The importance of coulomb explosions
AU - Corral, Inés
AU - Mó, Otilia
AU - Yáñez, Manuel
AU - Salpin, Jean Yves
AU - Tortajada, Jeanine
AU - Radom, Leo
PY - 2004/11/18
Y1 - 2004/11/18
N2 - The gas-phase reactions between urea and Ca2+ have been investigated by means of electrospray mass spectrometry techniques. The MS/MS spectra of [Ca(urea)]2+ and [Ca(urea-H)]+ complexes show that both ions decompose by losing NH3 and HNCO. However, for the [Ca(urea)]2+ system, additional intense peaks are observed at m/z 44, 56, and 82. Density functional theory calculations at the B3-LYP/cc-pWCVTZ level have been used to help rationalize these observations through an examination of the structures and bonding characteristics of the various stationary points on the [Ca(urea)]2- and [Ca(urea-H)]+ potential energy surfaces (PESs). Analysis of the topology of these PESs allows mechanisms to be proposed for the loss of NH3 and HNCO. In addition, for [Ca(urea)]2+, the calculations suggest that the m/z 44, 56, and 82 peaks correspond to H2NCO-, CaNH2 +, and [Ca, N, C, O]+, respectively, which are produced in Coulomb explosion processes. The unimolecular reactivity of [Ca(urea-H)] + differs from that of [Ca(urea)]2- largely through the absence of the Coulomb explosion fragmentations. Urea behaves as an oxygen base with respect to Ca2+, the calculated binding energy being 453 kJ mol-.
AB - The gas-phase reactions between urea and Ca2+ have been investigated by means of electrospray mass spectrometry techniques. The MS/MS spectra of [Ca(urea)]2+ and [Ca(urea-H)]+ complexes show that both ions decompose by losing NH3 and HNCO. However, for the [Ca(urea)]2+ system, additional intense peaks are observed at m/z 44, 56, and 82. Density functional theory calculations at the B3-LYP/cc-pWCVTZ level have been used to help rationalize these observations through an examination of the structures and bonding characteristics of the various stationary points on the [Ca(urea)]2- and [Ca(urea-H)]+ potential energy surfaces (PESs). Analysis of the topology of these PESs allows mechanisms to be proposed for the loss of NH3 and HNCO. In addition, for [Ca(urea)]2+, the calculations suggest that the m/z 44, 56, and 82 peaks correspond to H2NCO-, CaNH2 +, and [Ca, N, C, O]+, respectively, which are produced in Coulomb explosion processes. The unimolecular reactivity of [Ca(urea-H)] + differs from that of [Ca(urea)]2- largely through the absence of the Coulomb explosion fragmentations. Urea behaves as an oxygen base with respect to Ca2+, the calculated binding energy being 453 kJ mol-.
UR - http://www.scopus.com/inward/record.url?scp=9944223808&partnerID=8YFLogxK
U2 - 10.1021/jp046624z
DO - 10.1021/jp046624z
M3 - Article
SN - 1089-5639
VL - 108
SP - 10080
EP - 10088
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 46
ER -