Conformational effect on gas-phase protonation and NH4+ clustering of 1,2-diols

✍ Scribed by Guy Bouchoux; Sylvie Jezequel; Florence Penaud-Berruyer

• Book ID: 102964821
• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 593 KB
• Volume: 28
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210280426

✦ Synopsis

Ab initio molecular orbital calculations at the MP2/6-31G*//3-21G level are reported on conformers of neutral ethane-1,2-diol (ethylene glycol; l), its protonated from 1H' and the ammonium adduct [ lNH,] + for an OCCO dihedral angle (0) of 0-180'. The proton affinity (PA) of 1 was determined in ion cyclotron resonance bracketing experiments to be 820 f 3 kJ mol-'. An adduct stabilization energy of 134 kJ mol-' was calculated for [ lNH,] ' . Total optimization at the 3-216 level of cis-and trms-cyclopentane-l,Zdiol(2 and 3) and their protonated forms 2H' and 3H' showed distorted envelope structures with 0 values of 47.2", 73.4', 33.0" and 58.0°, respectively. The calculation predicts PA(2) = 845 kJ mol-' and PA(3) = 815 kJ mol-'.