TY - JOUR
T1 - Structures and thermochemistry of the alkali metal monoxide anions, monoxide radicals, and hydroxides
AU - Mintz, Benjamin
AU - Chan, Bun
AU - Sullivan, Michael B.
AU - Buesgen, Thomas
AU - Scott, Anthony P.
AU - Kass, Steven R
AU - Radom, Leo
AU - Wilson, Angela K.
PY - 2009/8/27
Y1 - 2009/8/27
N2 -
The geometries, enthalpies of formation (ΔH°
f
), separations of electronic states, electron affinities, gas-phase acidities, and bond dissociation energies associated with the alkali metal monoxide anions (MO
-
), monoxide radicals (MO
.
), and hydroxides (MOH) (M = Li, Na, and K) have been investigated using single-reference and multireference variants of the WnC procedures. Our best estimates of the ΔH°
f
values for the ground states at 298 K are as follows: 8.5 (
3
π LiO
-
), 48.5 (
2
π LiO), -243.4 (
1
σ
+
LiOH), 34.2 (
3
π NaO
-
), 86.4 (
2
π NaO
.
), -190.8 (
1
σ
+
NaOH), 15.1 (
1
σ
+
KO
-
), 55.9 (
2
σ
+
KO
.
), and -227.0 (
1
σ+ KOH) kJ mol
-1
. While the LiO
.
and NaO
.
radicals have
2
π ground states, for KO
.
, the
2
π+ and
2
π electronic states lie very close in energy, with our best estimate being a preference for the
2
σ
+
state by 1.1 kJ mol
-1
at 0 K. In a similar manner, the ground state for MO
-
changes from
3
π for LiO
-
and NaO
-
to
1
π
+
for KO
-
. The
1
σ
+
state of KO
-
is indicated by the calculated
1
diagnostic and the SCF contribution to the total atomization energy to have a significant degree of multireference character. This leads to a difference of more than 100 kJ mol
-1
between the single-reference W2C and multireference W2C-CAS-ACPF and W2C-CAS-AQCC estimates for the
1
σ
+
δH°
f
for KO
-
.
AB -
The geometries, enthalpies of formation (ΔH°
f
), separations of electronic states, electron affinities, gas-phase acidities, and bond dissociation energies associated with the alkali metal monoxide anions (MO
-
), monoxide radicals (MO
.
), and hydroxides (MOH) (M = Li, Na, and K) have been investigated using single-reference and multireference variants of the WnC procedures. Our best estimates of the ΔH°
f
values for the ground states at 298 K are as follows: 8.5 (
3
π LiO
-
), 48.5 (
2
π LiO), -243.4 (
1
σ
+
LiOH), 34.2 (
3
π NaO
-
), 86.4 (
2
π NaO
.
), -190.8 (
1
σ
+
NaOH), 15.1 (
1
σ
+
KO
-
), 55.9 (
2
σ
+
KO
.
), and -227.0 (
1
σ+ KOH) kJ mol
-1
. While the LiO
.
and NaO
.
radicals have
2
π ground states, for KO
.
, the
2
π+ and
2
π electronic states lie very close in energy, with our best estimate being a preference for the
2
σ
+
state by 1.1 kJ mol
-1
at 0 K. In a similar manner, the ground state for MO
-
changes from
3
π for LiO
-
and NaO
-
to
1
π
+
for KO
-
. The
1
σ
+
state of KO
-
is indicated by the calculated
1
diagnostic and the SCF contribution to the total atomization energy to have a significant degree of multireference character. This leads to a difference of more than 100 kJ mol
-1
between the single-reference W2C and multireference W2C-CAS-ACPF and W2C-CAS-AQCC estimates for the
1
σ
+
δH°
f
for KO
-
.
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U2 - 10.1021/jp9034826
DO - 10.1021/jp9034826
M3 - Article
C2 - 19650655
AN - SCOPUS:68949212234
VL - 113
SP - 9501
EP - 9510
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
SN - 1089-5639
IS - 34
ER -