The synthesis of a number of pentaborate(1-) salts from cations arising from
N-substituted α,α-, α,β-, and α,γ-diaminoalkanes has been attempted in aqueous solution from B(OH)
3 and the appropriate diammine in a 10:1 ratio. Despite relatively mild work-up conditions the pentaborate(1-) salts
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The synthesis of a number of pentaborate(1-) salts from cations arising from
N-substituted α,α-, α,β-, and α,γ-diaminoalkanes has been attempted in aqueous solution from B(OH)
3 and the appropriate diammine in a 10:1 ratio. Despite relatively mild work-up conditions the pentaborate(1-) salts prepared were not always as anticipated and the following compounds were isolated in good yield: [Me
2NH(CH
2)
2NHMe
2][B
5O
6(OH)
4]
2 (
1), [Et
2NH(CH
2)
2NHEt
2][B
5O
6(OH)
4]
2 (
2), [Et
2NH
2][B
5O
6(OH)
4] (
3), [Me
2NH
2][B
5O
6(OH)
4] (
4), [Me
2NH(CH
2)
3NHMe
2][B
5O
6(OH)
4]
2 (
5), [Et
2NH(CH
2)
3NHEt
2][B
5O
6(OH)
4]
2 (
6), [Me
3NCH
2CH=CH
2][B
5O
6(OH)
4] (
7), and [Me
3N(CH
2)
3NMe
3] [B
5O
6(OH)
4]
2.0.5H
2O (
8). The tetraborate(2-) salt, [Me
3N(CH
2)
2NMe
3][B
4O
5(OH)
4]
.2B(OH)
3.2H
2O (
9) was obtained in moderate yield (41%) from a 3:1 reaction of B(OH)
3 with [Me
3N(CH
2)
2NMe
3](OH)
2. All compounds were characterized by spectroscopy (
1H,
11B,
13C NMR and IR) and thermal gravimetric analysis (TGA). BET analysis on materials derived thermally from selected samples (
1,
2,
6,
7) all had porosities of < 1 m
2/g, demonstrating that they were non-porous. Single-crystal XRD structures were obtained for
2,
3,
7,
8 and
9 and all contain extensive H-bonded polyborate lattices.
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