pronounced as for trioxoborate. The B-O and B-OH stretching frequencies decrease
when going from Hartree-Fock to the correlated levels, as expected. When going
from nondiffuse to diffuse basis sets, the B-O stretching frequencies decrease, but
the B-OH frequency increases. The other frequencies do not show any surprising
trends.
4 Conclusions
The calculated bond lengths and vibrational frequencies of boric acid and borate
agree fairly well with that observed experimentally and with previous calculations,
where available, when the comparison is appropriate. The oxodihydroxoborate ion
is much more stable than the boric acid-hydroxide complex, when the latter exists.
The oxodihydroxoborate ion, if it can be observed, should have a strong vibrational
band at approximately 1400–1600 cm
−1 . A transition state that links the tetrahydroxoborate to the hydrated oxodihydroxoborate ion has been found. The addition
of water molecules lowers the barrier significantly, bringing the activation energy to
closer agreement with experiment (assuming an oxodihydroxoborate intermediate).
Acknowledgements The author acknowledges the Atlantic Computational Excellence Network
(ACEnet) for computational support.
References
1. Richens DT (1997) The chemistry of aqua ions. Wiley, Chichester
2. Oi T (2000) Calculations of reducted partition function ratios of monomeric and dimeric boric
acids and borates by the ab initio molecular orbital theory. J Nucl Sci Tech 37(2):166–172
Table 15 Vibrational frequencies (cm
−1
) of the C s #1 form of BO 2 (OH)
2−
Level
BO 3 i.p
def
BO
(H) str
OHtors BO 3 i.p
def
BO 3 o.o.
p def
OH
def
BO
str
BO
str
A′
A′
A″
A′
A″
A′
A′
A′
HF/6-31G*
453
491
547
723
812
1052 1134 1661
HF/6-31+G*
471
523
572
719
812
1080 1104 1557
HF/6-311+G*
472
515
560
704
811
1086 1093 1551
B3LYP/6-31G*
391
426
523
656
724
958 1047 1563
B3LYP/6-31+G*
416
476
543
635
712
986 1014 1426
B3LYP/6-311+G* 417
467
528
615
710
990 1007 1424
MP2/6-31G*
397
445
537
668
737
973 1050 1572
MP2/6-31+G*
418
478
547
643
708
991 1001 1406
MP2/6-311+G*
425
480
518
639
703
995 1001 1408
174
C. C. Pye
when going from Hartree-Fock to the correlated levels, as expected. When going
from nondiffuse to diffuse basis sets, the B-O stretching frequencies decrease, but
the B-OH frequency increases. The other frequencies do not show any surprising
trends.
4 Conclusions
The calculated bond lengths and vibrational frequencies of boric acid and borate
agree fairly well with that observed experimentally and with previous calculations,
where available, when the comparison is appropriate. The oxodihydroxoborate ion
is much more stable than the boric acid-hydroxide complex, when the latter exists.
The oxodihydroxoborate ion, if it can be observed, should have a strong vibrational
band at approximately 1400–1600 cm
−1 . A transition state that links the tetrahydroxoborate to the hydrated oxodihydroxoborate ion has been found. The addition
of water molecules lowers the barrier significantly, bringing the activation energy to
closer agreement with experiment (assuming an oxodihydroxoborate intermediate).
Acknowledgements The author acknowledges the Atlantic Computational Excellence Network
(ACEnet) for computational support.
References
1. Richens DT (1997) The chemistry of aqua ions. Wiley, Chichester
2. Oi T (2000) Calculations of reducted partition function ratios of monomeric and dimeric boric
acids and borates by the ab initio molecular orbital theory. J Nucl Sci Tech 37(2):166–172
Table 15 Vibrational frequencies (cm
−1
) of the C s #1 form of BO 2 (OH)
2−
Level
BO 3 i.p
def
BO
(H) str
OHtors BO 3 i.p
def
BO 3 o.o.
p def
OH
def
BO
str
BO
str
A′
A′
A″
A′
A″
A′
A′
A′
HF/6-31G*
453
491
547
723
812
1052 1134 1661
HF/6-31+G*
471
523
572
719
812
1080 1104 1557
HF/6-311+G*
472
515
560
704
811
1086 1093 1551
B3LYP/6-31G*
391
426
523
656
724
958 1047 1563
B3LYP/6-31+G*
416
476
543
635
712
986 1014 1426
B3LYP/6-311+G* 417
467
528
615
710
990 1007 1424
MP2/6-31G*
397
445
537
668
737
973 1050 1572
MP2/6-31+G*
418
478
547
643
708
991 1001 1406
MP2/6-311+G*
425
480
518
639
703
995 1001 1408
174
C. C. Pye