作者:Monika C. Haberecht、Michael Bolte、Matthias Wagner、Hans-Wolfram Lerner
DOI:10.1007/s10870-005-3325-y
日期:2005.9
A new orthorhombic polymorph of tri(p-tolyl)boroxine (Pmn21) with relatively short intermolecular B–O distances of 3.321 Å was crystallized from CDCl3 at ambient temperature. The crystal structure of the orthorhombic polymorph of tri(p-tolyl)boroxine shows the shortest intermolecular B–O contact yet found in boroxines. The cell dimensions of the orthorhombic polymorph of tri(p-tolyl)boroxine are a = 21.888(4) Å, b = 9.304(2) Å, and c = 4.7804(10) Å. The structural features of the orthorhombic polymorph of tri(p-tolyl)boroxine are quite different from a previously reported monoclinic (Beckett et al., J. Organomet. Chem. 1997, 535, 33–41) but similar to that of tri(p-bromophenyl)boroxine (Avent et al., Coll. Czech. Chem. Commun. 2002, 67, 1051–1060). Obviously, electronic effects of substituents on the boron centers influence the structural features of substituted boroxines less than discussed in earlier reports (Boese et al., Angew. Chem. 1987, 99, 239–241).
在环境温度下,从 CDCl3 中结晶出一种新的正交多晶型三(对甲苯基)硼氧烷 (Pmn21),其分子间 B-O 距离相对较短,为 3.321 Å。三(对甲苯基)硼氧烷正交多晶体的晶体结构显示出迄今为止在硼氧化合物中发现的最短的分子间 B-O 接触。三(对甲苯基)硼氧烷正方多晶体的晶胞尺寸为 a = 21.888(4) Å,b = 9.304(2) Å,c = 4.7804(10) Å、J.Organomet.Chem.1997,535,33-41),但与三(对溴苯基)硼氧烷的结构相似(Avent 等人,Coll.Czech.Chem.Commun.2002,67,1051-1060)。很明显,取代基对硼中心的电子效应对取代硼氧烷结构特征的影响比早期报告(Boese 等人,Angew.)