Darstellung, 11B-, 13C-, 1H-NMR-Spektren und Schwingungsspektren von 1,2-Xylylen-pentahydro-closo-hexaborat,cis-[B6H5(CH2)2C6H4]- , sowie Kristallstrukturen von cis-[P(C6H5)4][B6H5(CH2)2C6H4] und cis-[(n-C4H9)4N][B6H5(CH2)2C6H4] / Preparation, 11B, 13C, 1H NMR Spectra and Vibrational Spectra of 1,2-Xylylene-pentahydro-closo-hexaborate, cis-[B6H5(CH2)2C6H4]-, and the Crystal Structures of cis-[P(C6H5)4][B6H5(CH2)2C6H4] and cis-[(n-C4H9)4N ][B6H5(CH2)2C6H4

Abstract

By reaction of [B6H6]2- with ω,ω′-dibromo-o-xylene in acetonitrile the 1,2-xylylenepentahydro-closo-hexaborat, cis-[B6H5(CH2)2C6H4]- , is formed. The new ansa compound has been separated from excess [B6H6]2- and other reaction products by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structures of cis-[P(C6H5)4][B6H5(CH2)2C6H4] (I) and as-[(n-C4H9)4N][B6H5(CH2)2C6H4] (II) have been determined by single crystal X-ray diffraction analysis: I is monoclinic, space group P 21/n with a = 13.715(5), b = 11.118(1) and c = 19.702(2) Å, β = 103.47(2)°; II is orthorhombic with a = 10.204(7), b = 13.352(4) and c = 20.824(8) Å. The 11B NMR spectrum confirms the structure with a hetero disubstituted octahedral B6 cage with local C2v symmetry. The 13C and 1H NMR spectra have been assigned in term of such a configuration. The IR and Raman spectra exhibit characteristic CH, BH, BC, B6 and arene vibrations.