Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5419136 | Journal of Molecular Structure: THEOCHEM | 2007 | 8 Pages |
Abstract
The dehydrogenation reactions of bimetallic species RhMCH2+ (M = Pt, Rh) with ammonia have been investigated by carrying out density functional calculations. Equilibrium structures and energies have been determined for intermediates and transition states in these reactions. Present results show that both metal-carbene cations have the reactivity similar to that of Pt2CH2+. The variatation of spin multiplicity can further modify significantly their dehydrogenation activities with NH3. In the reaction of RhMCH2+ (M = Pt, Rh) with NH3, elimination of H2 exclusively arises from the moiety of CH2 and no N-H bond activation of ammonia takes place. The favored dehydrogenation process occurs on the triplet state potential energy surface of RhPtCH2+ with NH3, followed by intersystem crossing from the triplet to the singlet states, then the Rh-mediated loss of H2 finally yields the singlet dehydrogenating product with Gibbs free energy ÎG about â37.0 kcal molâ1 (298.15 K). In the reaction of Rh2CH2+ with NH3, the doublet channel is favorable energetically. The overall low-cost pathway has a Gibbs free energy of ÎG about â26.1 kcal molâ1 (298.15 K).
Related Topics
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Authors
Jian Chen, Fei Xia, Zexing Cao, Menghai Lin,