Comparison of Isoelectronic Aluminum-Nitrogen and Silicon-Carbon Double Bonds Using Valence Bond Methods
Abstract
Dimethyl-aluminum amide ((CH3)2AlNH2) is a postulated intermediate in the reaction between trimethyl aluminum ((CH3)3Al) and ammonia to form aluminum nitride. Results of geometry optimization calculations for (CH3)2AlNH2, H2AlNH2 and isoelectronic H2SiCH2(silaethylene) are presented. Each of these has a planar equilibrium skeleton with C(2v) symmetry. Geometry optimizations were carried out using Generalized Valence Bond Perfect-Pairing (GVB-PP) wave functions. Al=Nitrogen bond distances of 1.78 and 1.80 A are predicted for the dihydro-and dimethyl-aluminum amides, respectively, slightly longer than the optimized Silicon=Carbon bond distance in silaethylene (1.74 A). Al=N bond distances in these compounds are fitted into a phenomenological correlation established by Haaland which relates the covalent:dative character of such a bond to the bond distance. We compare the Al=N and Si=C bonds in the shapes of the GVB-PP orbitals representing them and in their predicted dipole moments. (aw)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 15, 1990
- Accession Number
- ADA218715
Entities
People
- Charles H. Patterson
- Leonard V. Interrante
- Mary M. Lyman
- Richard P. Messmer
Organizations
- Rensselaer Polytechnic Institute