Molecular and Crystal Structure of Tris(methylanilido) Borane
نویسنده
چکیده
Die Bor-Stickstoff-Bindung in Aminoboranen R3_KB(NR2)« besitzt eine Bindungsordnung > 1 [2], die nach schwingungsspektroskopischen [3] und PE-spektroskopischen [2 b] Studien mit steigendem n abnimmt. Borund Stickstoffatome sind als sp2hybridisiert anzusehen, da beide Atomarten von je drei Nachbaratomen planar umgeben werden. Maximale Überlappung ihrer pz-Orbitale und damit optimale TI-Bindung wird bei Koplanarität der Gerüstatome erreicht. Verdrillung der C2NB-Ebenen gegen die BN3-Ebene verringert die Überlappung der p2-Orbitale; der TI-Bindungsanteil nimmt mitdem Cosinusquadrat des Verdrillungswinkels l ab. Konsequenterweise sollte daher der BN-Bindungsabstand mit steigender Verdrillung zunehmen. Ein derartiger Effekt wurde bei den zu den Triaminoboranen B(NR-2)3 atominversen Triborylaminen N(BR.2)3 beobachtet [4]: BN-Abstände um 144 pm liegen für die nahezu mit der BsN-Ebene koplanaren R2BGruppen vor gegenüber 148 pm für orthogonal stehende Gruppen. Die vorliegende Mitteilung beschreibt die Molekülstruktur von Tris(methylanilido)boran (1), einer Verbindung, von der erwartet wurde, daß ihre R2NB-Ebene stärker gegen die BN3-Ebene verdrillt sein würde als im Tris(dimethylamino)boran (6).
منابع مشابه
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