Gas-Phase Structures of Dimethylboron Azide and Dimethylboron Isocyanate. Electron Diffraction and ab Initio Study

Publication Type
Journal contribution
Authors
Hausser-Wallis, R.; Oberhammer, H.; Einholz, W.; Paetzold, P.
Year of publication
1990
Published in
Inorganic Chemistry
Band/Volume
29/18
Page (from - to)
3286-89
Abstract

The gas-phase structures of (CH3)2BN3 and (CH3)2BNCO have been detd. by electron diffraction. Both mols. have planar heavy-atom skeletons with bent BN3 and BNCO moieties. Their geometries differ mainly in the BNY bond angle (Y = NN or CO), which is small (.apprx.120.degree.) in the azide and large (.apprx.150.degree.) in the isocyanate. Structure analyses with a large amplitude model for (CH3)2BNCO and a double min. potential for the BNCO in-plane bending motion suggest that the barrier at the linear configuration is .gtoreq.0.2 kcal/mol. HF calcns. with 6-31G* basis sets reproduce the exptl. structure of the azide satisfactorily. Relative to the ground state, a configuration with a linear BN3 group and one with the azide group pointing out of the plane are resp. 15.0 and 12.1kcal/mol less stable. For (CH3)2BNCO the ab initio method predicts a linear BNCO structure, which is at variance with the exptl. result.

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