Scission of Carbon Monoxide Using TaR3, R=(N(tBu)Ph) or OSi(tBu)3: A DFT Investigation |
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| Authors: | Nigel J. Brookes Dr. Alireza Ariafard Dr. Robert Stranger Prof. Brian F. Yates Prof. |
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| Affiliation: | 1. School of Chemistry, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001 (Australia), Fax: (+61)?3‐6226‐2858;2. Department of Chemistry, Faculty of Science, Central Tehran Branch, Islamic Azad University, Shahrak Gharb, Tehran (Iran);3. Research School of Chemistry, The Australian National University, Canberra ACT 0200 (Australia) |
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| Abstract: | The experimentally known reduction of carbon monoxide using a 3‐coordinate [Ta(silox)3] (silox=OSi(tBu)3) complex initially forms a ketenylidene [(silox)3Ta? CCO], followed by a dicarbide [(silox)3Ta? CC? Ta(silox)3] structure. The mechanism for this intricate reaction has finally been revealed by using density functional theory, and importantly a likely structure for the previously unknown intermediate [(silox)3Ta? CO]2 has been identified. The analysis of the reaction pathway and the numerous intermediates has also uncovered an interesting pattern that results in CO cleavage, that being scission from a structure of the general form [(silox)3Ta? CnO] in which n is even. When n is odd, cleavage cannot occur. The mechanism has been extended to consider the effect of altering both the metal species and the ligand environment. Specifically, we predict that introducing electron‐rich metals to the right of Ta in the periodic table to create mixed‐metal dinuclear intermediates shows great promise, as does the ligand environment of the Cummins‐style 3‐coordinate amide structure. This latter environment has the added complexity of improved electron donation from amide rotation that can significantly increase the reaction exothermicity. |
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| Keywords: | carbon monoxide computational chemistry density functional calculations reaction mechanisms transition metals |
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