TY - JOUR
T1 - Magnesium monocationic complexes
T2 - A theoretical study of metal ion binding energies and gas-phase association kinetics
AU - Dunbar, Robert C.
AU - Petrie, Simon
PY - 2005/2/24
Y1 - 2005/2/24
N2 - Bond dissociation energies (BDEs) for complexes of ground state Mg + ( 2S) with several small oxygen- and nitrogen-containing ligands (H 2O, CO, CO 2, H 2CO, CH 3OH, HCOOH, H 2CCO, CH 3CHO, c-C 2H 4O, H 2CCHOH, CH 3CH 2OH, CH 3OCH 3, NH 3, HCN, H 2CNH, CH 3NH 2, CH 3CN, CH 3CH 2NH 2, (CH 3) 2NH, H 2NCN, and HCONH 2) have been calculated at the CP-dG2thaw level of theory. These BDE values, as well as counterpoise-corrected MP2(thaw)/6-311+G(2df,p) calculations on the Mg + complexes of several larger ligands, augment and complement existing experimental or theoretical determinations of gas-phase Mg +/ligand bond strengths. The reaction kinetics of complex formation are also investigated via variational transition state theory (VTST) calculations using the computed ligand and molecular ion parameters. Radiative association rate coefficients for most of these systems increase by approximately 1 order of magnitude with every 3-fold reduction in temperature from 300 to 10 K. Several of the largest molecules surveyed-notably, CH 3COOH, (CH 3) 2CO, and CH 3CH 2CN - exhibit comparatively efficient radiative association with Mg + (k RA ≥ 1.0 × 10 -10 cm 3 molecule -1 s -1) at temperatures as high as 100 K, implying that these processes may have a considerable influence on the metal ion chemistry of warm molecular astrophysical environments known to contain these potential ligands. Our calculations also identify the infrared chromophoric brightness of various functional groups as a significant factor influencing the efficiency of the radiative association process.
AB - Bond dissociation energies (BDEs) for complexes of ground state Mg + ( 2S) with several small oxygen- and nitrogen-containing ligands (H 2O, CO, CO 2, H 2CO, CH 3OH, HCOOH, H 2CCO, CH 3CHO, c-C 2H 4O, H 2CCHOH, CH 3CH 2OH, CH 3OCH 3, NH 3, HCN, H 2CNH, CH 3NH 2, CH 3CN, CH 3CH 2NH 2, (CH 3) 2NH, H 2NCN, and HCONH 2) have been calculated at the CP-dG2thaw level of theory. These BDE values, as well as counterpoise-corrected MP2(thaw)/6-311+G(2df,p) calculations on the Mg + complexes of several larger ligands, augment and complement existing experimental or theoretical determinations of gas-phase Mg +/ligand bond strengths. The reaction kinetics of complex formation are also investigated via variational transition state theory (VTST) calculations using the computed ligand and molecular ion parameters. Radiative association rate coefficients for most of these systems increase by approximately 1 order of magnitude with every 3-fold reduction in temperature from 300 to 10 K. Several of the largest molecules surveyed-notably, CH 3COOH, (CH 3) 2CO, and CH 3CH 2CN - exhibit comparatively efficient radiative association with Mg + (k RA ≥ 1.0 × 10 -10 cm 3 molecule -1 s -1) at temperatures as high as 100 K, implying that these processes may have a considerable influence on the metal ion chemistry of warm molecular astrophysical environments known to contain these potential ligands. Our calculations also identify the infrared chromophoric brightness of various functional groups as a significant factor influencing the efficiency of the radiative association process.
UR - http://www.scopus.com/inward/record.url?scp=14544277031&partnerID=8YFLogxK
U2 - 10.1021/jp046777m
DO - 10.1021/jp046777m
M3 - Article
SN - 1089-5639
VL - 109
SP - 1411
EP - 1419
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 7
ER -