Complementary anion binding by bidentate boron-containing Lewis acids

• Published in: Journal of organometallic chemistry Vol. 690; no. 11; pp. 2725 - 2731
• Main Authors: Coombs, Natalie D., Aldridge, Simon, Wiltshire, Gavin, Kays (née Coombs), Deborah L., Bresner, Christopher, Ooi, Li-ling
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-06-2005
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2005.01.015

Anion binding by the pyroborates (catB)
2O (
1, cat
=
O
2C
6H
4-1,2) and (
S,
S-Ph
2C
2H
2O
2B)
2O (
2) has been investigated by spectroscopic, structural and titration methods;
1 has been shown to act as a bifunctional Lewis acid in the complementary (1:1) binding of acetate both in the solid state and in solution (for which a binding constant of 1500
±
550
M
−1 has been determined).
Anion binding by the pyroborates (catB)
2O (
1, cat
=
O
2C
6H
4-1,2) and (
S,
S-Ph
2C
2H
2O
2B)
2O (
2) has been investigated by spectroscopic, structural and titration methods.
1 has been shown to act as a bifunctional Lewis acid, exemplified by the complementary (1:1) binding of bidentate bases such as acetate and dihydrogen phosphate. The former complex has been characterized in the solid state by X-ray diffraction and a binding constant of 1500
±
550
M
−1 determined in chloroform solution. The reaction of
2 with acetate, by contrast, leads to breakdown of the Lewis acid chelate and to the formation of the homochiral borate anion [(
S,
S-Ph
2C
2H
2O
2)
2B]
− in good yield (84% based on the chiral component).