Syntheses and Crystal Structures of the closo-Borates M2[B7H7] and M[B7H8] (M = PPh4, PNP, and N(n-Bu4)): the Missing Crystal Structure in the Series [B n H n ]2− (n = 6−12)

• Published in: Inorganic chemistry 2011-03, Vol.50 (6), p.2580-2589
• Main Authors: Schlüter, Florian, Bernhardt, Eduard
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic102434t

Oxidation of [N(n-Bu4)]2[B9H9] with oxygen in a mixture of dimethoxyethane and CH2Cl2 leads to salts of the [B7H7]2− dianion. This is the first convenient synthesis for a seven-vertex hydro-closo-borate anion. Protonation with NEt3·HCl resulted in salts of the [B7H8]− monoanion. Both closo-borate anions were isolated and characterized by 1H, 1H{11B}, 11B, and 11B{1H} NMR spectroscopy. The temperature-dependent 1H{11B}, 11B, and 11B{1H} NMR spectra of [B7H8]− were also measured. The structure of [B7H7]2− as well as of [B7H8]− were determined by single-crystal X-ray diffraction.