Synthesis and thermal studies of two phosphonium tetrahydroxidohexaoxidopentaborate(1-) salts: single-crystal XRD characterization of [iPrPPh3][B5O6(OH)4]·3.5H2O and [MePPh3][B5O6(OH)4]·B(OH)3·0.5H2O †
Synthesis and thermal studies of two phosphonium tetrahydroxidohexaoxidopentaborate(1-) salts: single-crystal XRD characterization of [iPrPPh3][B5O6(OH)4]·3.5H2O and [MePPh3][B5O6(OH)4]·B(OH)3·0.5H2O †
Two substituted phosphonium tetrahydoxidohexaoxidopentaborate(1-) salts, [
iPrPPh
3][B
5O
6(OH)
4]·3.5H
2O (
1) and [MePPh
3][B
5O
6(OH)
4]·B(OH)
3·0.5H
2O (
2), were prepared by templated self-assembly processes with good yields by crystallization from basic methanolic aqueous solutions primed with B(OH)
3 and the appropriate phosphonium cation. Salts
1 and
2 were characterized by spectroscopic (NMR and IR) and thermal (TGA/DSC) analysis. Salts
1 and
2 were thermally decomposed in air at 800 °C to glassy solids via the anhydrous phosphonium polyborates that are formed at lower temperatures (<300 °C). BET analysis of the anhydrous and pyrolysed materials indicated they were non-porous with surface areas of 0.2-2.75 m
2/g. Rhe recrystallization of
1 and
2 from aqueous solution afforded crystals suitable for single-crystal XRD analyses. The structure of
1 comprises alternating cationic/anionic layers with the H
2O/pentaborate(1-) planes held together by H-bonds. The cationic planes have offset face-to-face (
off) and vertex-to-face (
vf) aromatic ring interactions with the
iPr groups oriented towards the pentaborate(1-)/H
2O layers. The anionic lattice in
2 is expanded by the inclusion of B(OH)
3 molecules to accommodate the large cations; this results in the formation of a stacked pentaborate(1-)/B(OH)
3 structure with channels occupied by the cations. The cations within the channels have
vf,
ef (edge-to-face), and
off phenyl embraces. Both H-bonding and phenyl embrace interactions are important in stabilizing these two solid-state structures.
organotriphenylphosphonium salts, pentaborate(1-), phenyl embraces, phosphonium salts, tetrahydroxidohexaoxidopentaborate(1-), X-ray structures, π-interactions
Beckett, Michael A.
5b021ef6-fa5c-4f6d-9998-3313558f0dc1
Horton, Peter N.
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Timmis, James L.
3bc450de-1482-49d1-8e75-3d957a989300
29 September 2023
Beckett, Michael A.
5b021ef6-fa5c-4f6d-9998-3313558f0dc1
Horton, Peter N.
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Timmis, James L.
3bc450de-1482-49d1-8e75-3d957a989300
Beckett, Michael A., Horton, Peter N., Hursthouse, Michael B. and Timmis, James L.
(2023)
Synthesis and thermal studies of two phosphonium tetrahydroxidohexaoxidopentaborate(1-) salts: single-crystal XRD characterization of [iPrPPh3][B5O6(OH)4]·3.5H2O and [MePPh3][B5O6(OH)4]·B(OH)3·0.5H2O †.
Molecules, 28 (19), [6867].
(doi:10.3390/molecules28196867).
Abstract
Two substituted phosphonium tetrahydoxidohexaoxidopentaborate(1-) salts, [
iPrPPh
3][B
5O
6(OH)
4]·3.5H
2O (
1) and [MePPh
3][B
5O
6(OH)
4]·B(OH)
3·0.5H
2O (
2), were prepared by templated self-assembly processes with good yields by crystallization from basic methanolic aqueous solutions primed with B(OH)
3 and the appropriate phosphonium cation. Salts
1 and
2 were characterized by spectroscopic (NMR and IR) and thermal (TGA/DSC) analysis. Salts
1 and
2 were thermally decomposed in air at 800 °C to glassy solids via the anhydrous phosphonium polyborates that are formed at lower temperatures (<300 °C). BET analysis of the anhydrous and pyrolysed materials indicated they were non-porous with surface areas of 0.2-2.75 m
2/g. Rhe recrystallization of
1 and
2 from aqueous solution afforded crystals suitable for single-crystal XRD analyses. The structure of
1 comprises alternating cationic/anionic layers with the H
2O/pentaborate(1-) planes held together by H-bonds. The cationic planes have offset face-to-face (
off) and vertex-to-face (
vf) aromatic ring interactions with the
iPr groups oriented towards the pentaborate(1-)/H
2O layers. The anionic lattice in
2 is expanded by the inclusion of B(OH)
3 molecules to accommodate the large cations; this results in the formation of a stacked pentaborate(1-)/B(OH)
3 structure with channels occupied by the cations. The cations within the channels have
vf,
ef (edge-to-face), and
off phenyl embraces. Both H-bonding and phenyl embrace interactions are important in stabilizing these two solid-state structures.
Text
molecules-28-06867
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More information
Accepted/In Press date: 27 September 2023
Published date: 29 September 2023
Keywords:
organotriphenylphosphonium salts, pentaborate(1-), phenyl embraces, phosphonium salts, tetrahydroxidohexaoxidopentaborate(1-), X-ray structures, π-interactions
Identifiers
Local EPrints ID: 483720
URI: http://eprints.soton.ac.uk/id/eprint/483720
ISSN: 1420-3049
PURE UUID: 0b57398f-28ca-4697-bd4f-86e5246f68a6
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Date deposited: 03 Nov 2023 18:00
Last modified: 18 Mar 2024 02:51
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Contributors
Author:
Michael A. Beckett
Author:
Peter N. Horton
Author:
James L. Timmis
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