Investigation of Catalytic Dehydrocoupling of Dimethylamine-borane by Titanocene: A DFT and Topologic Study
Abstract
With the increasing demand of clean energy carriers, ammonia borane and its related amine borane (AB) compounds [1] have emerged as attractive candidates for potential hydrogen storage vectors. In this context, mechanistic studies for the catalyzed dehydrogenation/dehydrocoupling of amine-boranes and phosphine-boranes have seen a quick development over the last decade. [2] Inexpensive, environmentally friendly, easily synthesized and stable organometallic compounds that efficiently catalyze the reaction are worth studying.
The dehydrocoupling of HMe2N·BH3 to form [Me2N·BH2]2 catalyzed by titanocene was investigated both experimentally [3, 4] and theoretically. [5] However, the exact mechanism of this reaction still remains uncertain. Theoretical studies based on DFT calculation and topological tools were used to characterize precisely the reaction pathway and 3-centre 2-electron (3C/2e) intermediates. The following aspects will be developed:
- The 3C/2e interactions between metallic centre and B-H σ bond are characterized in both intermolecular intermediates (σ complexes) and intramolecular ones (agostic complexes).
- The empirical dispersion correction (GD3BJ) is shown to yield structures and relative energies for the different reaction pathways, in better agreement with experimental observations.
- The solvation effect associated with different basis sets may be a remarkable parameter that influences the energetic properties of this kind of reaction. Further investigations should help in finding an inexpensive and highly-efficient catalyst.
[1] F. H. Stephens, V. Pons and R. T. Baker, Dalton Trans. 25, 2613 (2007).
[2] H. C. Johnson, T. N. Hooper and A. S. Weller, Springer International Publishing 153 (2015).
[3] T. J. Clark, C. A. Russell and I. Manners, J. Am. Chem. Soc. 128, 9582 (2006).
[4] M. E. Sloan, A. Staubitz, T. J. Clark, C. A. Russell, G. C. Lloyd-Jones and I. Manners, J. Am. Chem. Soc. 132, 3831 (2010).
[5] Y. Luo and K. Ohno, Organometallics 26, 3597 (2007).
Origin : Files produced by the author(s)