| Abstract
| - A systematic quantum chemical investigation of mono-, di-, and triaminoborane, -alane, -gallane, and -indane iscarried out to determine quantitatively the effects of pi bonding and negative hyperconjugation on structures, energetics,and rotational barriers in these systems. Pi bonding plays a significant role in the aminoborane compounds, butbecomes rapidly less significant in the aminoalanes, -gallanes, and -indanes. For each main-group metal Xinvestigated, X−N rotational barriers are found to be essentially equal depending only on the number of remainingin-plane amino groups. The contribution of negative hyperconjugation to reducing rotational barriers, as assessedfrom natural bond orbital (NBO) delocalization energies, is independent of the pyramidalization of the out-of-planeamino group, and is also dependent only on the number of rotated groups. Optimized tris[bis(trimethylsilyl)amino]-substituted structures of boron, aluminum, gallium, and indium are found to compare quite well with availableexperimental structural data, and exhibit X−N torsion angles that are independent of the central metal atom.
- A quantum chemical investigation of mono-, di-, and triaminoborane, -alane, -gallane, and -indane is carried out to determine quantitatively the effects of pi bonding and negative hyperconjugation on structures, energetics and rotational barriers. Pi bonding plays a significant role in the aminoborane compounds, but is less significant in the others. Optimized tris[bis(trimethylsilyl)amino]-substituted structures are found to compare well with experimental structural data, and exhibit X−N torsion angles that are independent of the central metal atom.
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