Mariona Sodupe

A theoretical study of the positive and dipositive ions of M(NH3)n and M(H2O)n for M=Mg, Ca, or Sr

The structure and binding energies are determined for many of the M(H2O)+n and M(H2O)2+n species, for n=1–3 and M=Mg, Ca, or Sr. The trends are explained in terms of metal sp or sdσ hybridization and core polarization. The M(NH3)+n systems, with M=Mg or Sr, are also studied. For the positive ions, the low‐lying excited states are also studied and compared with experiment. The calculations suggest an alternative interpretation of the SrNH+3 spectrum.

A theoretical study of Mg(CO2)+n and Sr(CO2)+n for n = 1 and 2 and Mg2CO+2

The structure and binding energies are determined for Mg(CO2)+n and Sr(CO2)+n for n = 1 and 2. We also consider Mg+2 and Mg2CO+2 to compare the binding of CO2 to a single metal ion with the binding to a diatomic ion. The vertical excitation energies are computed for all species. The potential energy curves for the low-lying states of Mg+2 are reported. The MgCO+2 results are in good agreement with the experimental results of Duncan and co-workers.

A theoretical study of the spectroscopy of MgH2O+ and MgCH3OH+

Abstract The structures, binding energies, and vibrational frequencies have been determined for the ground and excited states of MgCH 3 OH + . The vibrational frequencies are also reported for the four lowest electronic states of MgH 2 O + to supplement our previous vertical excitation energies.

Theoretical determination of the alkali-metal superoxide bond energies

The bond dissociation energies for the alkali-metal superoxides have been computed using extensive Gaussian basis sets and treating electron correlation at the modified coupled-pair functional level. Our computed D0 values are 61.4, 37.2, 40.6, and 38.4 kcal/mol for LiO2, NaO2, KO2, and RbO2, respectively. These values, which are expected to be lower bounds and accurate to 2 kcal/mol, agree well with some of the older flame data, but rule out several recent experimental measurements.

The calculation of the vibrational frequencies of CuCO+, NiCO and CuCH3

Abstract The vibrational frequencies of CuCO + , NiCO, and CuCH 3 are computed at both the self-consistent-field (SCF) and coupled-cluster singles and doubles, with a perturbational estimate of the triples (CCSD(T)), levels of theory. Overall the SCF frequencies are in qualitative agreement with the CCSD(T) results. The calculations show that the frequencies for the electrostatically bound CuCO + are quite different from the datively bound NiCO. The CCSD(T) calculations support a previous suggestion that the CH stretches in CuCH 3 have been misassigned.

The bonding in the low-lying states of MgO+2

Abstract The 2 A 2 ground state of MgO + 2 is of Mg 2+ O − 2 character with an Mg + −O 2 binding energy of 23.3 kcal/mol. The linear 4 Σ − state, which is bound by a charge—quadrupole interaction, has a significantly smaller binding energy (5.9 kcal/mol). Unlike many Mg + -ligand systems, there are no observable bound—bound transitions for MgO + 2 below 35000 cm −1 .

The bonding in FeC5H+5

Abstract The computed binding energy of 77 ± 10 kcal/mol for the 2 E 2 state of Fe + −C 5 H 5 is in reasonable agreement with the experimental value of 88 ± 7 kcal/mol. The Fe + binding energy for C 5 H 5 is much larger than that found for C 6 H 6 , as found in experiment. While the electrostatic bonding in FEC 6 H + 6 is enhanced by Fe to Ligand π * donation, the electrostatic bonding in FeC 5 H + 5 is enhanced by the formation of a bond between the open-shell π orbital on C 5 H 5 and Fe + .

The metal‐ligand binding energies for Sr(H2O)+n

Based on accurate ab initio calculations, we estimate the successive binding energies of one and two waters to Sr+ to be 25±3 and 23±3 kcal/mol. These are about 10 kcal/mol smaller than the experimental values. Since both experiment and theory are expected to be highly accurate, an alternative determination would be desirable.

A theoretical study of the spectroscopy of SrH2O+ and SrNH+3

The structure, binding energies, and vibrational frequencies are determined for the excited states of SrH2O+ and SrNH+3 to supplement our previous results for the ground state and vertical excitation energies.

Theoretical study of the 2A22B2 separation of the alkali superoxides

Abstract The computed 2 A 2  2 B 2 separations of the alkali superoxides are in good agreement with those deduced from electron-spin resonance spectra. The calculations definitively show that the ground state of CsO 2 is 2 A 2 . The larger than expected separation for CsO 2 , based on the trend from LiO 2 to RbO 2 , is attributed primarily to the differential effects of core relaxation. The CsO 2 dissociation energy is computed to be 42.7 kcal/mol, with an uncertainty conservatively estimated as ±4 kcal/mol.