A Crystallographic Review of Alkali
Borate Salts and Ab Initio Study
of Borate Ions/Molecules
Cory C. Pye
Abstract The crystal structures of alkali metal borate salts are reviewed. A wide
diversity of structures is noted. Structures with discrete ions containing two or more
boron atoms are targeted for further study with ab initio methods (HF, B3LYP, and
MP2) using modest basis sets (6-31G*, 6-31+G* and 6-311+G*). The ions identified for study are: [B 3 O 6 ]
3−
, [B 3 O 5 (OH) 2 ]
3− , [B 3 O 4 (OH) 4 ]
3−
, [B 3 O 3 (OH) 4 ]
−
,
[B 4 O 5 (OH) 4 ]
2− , [B 5 O 6 (OH) 4 ]
−
, [B 2 O 5 ]
4−
, and [B 4 O 9 ]
6−
. Some structurally related
ions are examined, and an investigation of the diborates launched, including [B 2 O
(OH) 6 ]
2−
, observed in the magnesium salt, and [B 2 (OH) 7 ]
−
, postulated as the
intermediate responsible for signal exchange between borate anion and boric acid in
11 B NMR. The B-O bond distances and general structures are in good agreement
with both crystallographic data and previous ab initio calculations.
Keywords Crystal structure ⋅ Ab initio study ⋅ Alkali borate ⋅ Polyborate
1 Introduction
In the preceding paper, the importance of the speciation of boron (III) to geochemistry, oceanography, and the nuclear industry, was discussed [1]. In addition,
the crystal structures of boron oxide, boric acid, and monomeric forms of sodium
and lithium borates were presented and discussed. Molecular forms exist for the
orthoboric acid [B(OH) 3 ] and metaboric acid [B 3 O 3 (OH) 3 ], and certain lithium and
sodium borates contain discrete [B(OH) 4 ]
−
, [BO 2 (OH)]
2−
, and [BO 3 ]
3− ions.
The structure, energy, and vibrational frequencies of the crystallographically
Electronic supplementary material The online version of this chapter (https://doi.org/10.1007/
978-3-319-74582-4_7) contains supplementary material, which is available to authorized users.
C. C. Pye ( ✉ )
Department of Chemistry, Saint Mary’s University, Halifax, NS B3H 3C3, Canada
e-mail: cory.pye@smu.ca
© Springer International Publishing AG, part of Springer Nature 2018
Y. A. Wang et al. (eds.), Concepts, Methods and Applications of Quantum Systems
in Chemistry and Physics, Progress in Theoretical Chemistry and Physics 31,
https://doi.org/10.1007/978-3-319-74582-4_7
107
Borate Salts and Ab Initio Study
of Borate Ions/Molecules
Cory C. Pye
Abstract The crystal structures of alkali metal borate salts are reviewed. A wide
diversity of structures is noted. Structures with discrete ions containing two or more
boron atoms are targeted for further study with ab initio methods (HF, B3LYP, and
MP2) using modest basis sets (6-31G*, 6-31+G* and 6-311+G*). The ions identified for study are: [B 3 O 6 ]
3−
, [B 3 O 5 (OH) 2 ]
3− , [B 3 O 4 (OH) 4 ]
3−
, [B 3 O 3 (OH) 4 ]
−
,
[B 4 O 5 (OH) 4 ]
2− , [B 5 O 6 (OH) 4 ]
−
, [B 2 O 5 ]
4−
, and [B 4 O 9 ]
6−
. Some structurally related
ions are examined, and an investigation of the diborates launched, including [B 2 O
(OH) 6 ]
2−
, observed in the magnesium salt, and [B 2 (OH) 7 ]
−
, postulated as the
intermediate responsible for signal exchange between borate anion and boric acid in
11 B NMR. The B-O bond distances and general structures are in good agreement
with both crystallographic data and previous ab initio calculations.
Keywords Crystal structure ⋅ Ab initio study ⋅ Alkali borate ⋅ Polyborate
1 Introduction
In the preceding paper, the importance of the speciation of boron (III) to geochemistry, oceanography, and the nuclear industry, was discussed [1]. In addition,
the crystal structures of boron oxide, boric acid, and monomeric forms of sodium
and lithium borates were presented and discussed. Molecular forms exist for the
orthoboric acid [B(OH) 3 ] and metaboric acid [B 3 O 3 (OH) 3 ], and certain lithium and
sodium borates contain discrete [B(OH) 4 ]
−
, [BO 2 (OH)]
2−
, and [BO 3 ]
3− ions.
The structure, energy, and vibrational frequencies of the crystallographically
Electronic supplementary material The online version of this chapter (https://doi.org/10.1007/
978-3-319-74582-4_7) contains supplementary material, which is available to authorized users.
C. C. Pye ( ✉ )
Department of Chemistry, Saint Mary’s University, Halifax, NS B3H 3C3, Canada
e-mail: cory.pye@smu.ca
© Springer International Publishing AG, part of Springer Nature 2018
Y. A. Wang et al. (eds.), Concepts, Methods and Applications of Quantum Systems
in Chemistry and Physics, Progress in Theoretical Chemistry and Physics 31,
https://doi.org/10.1007/978-3-319-74582-4_7
107