Reactions of methyliron(1+) and methylcobalt(1+) ions with aliphatic alkanes in the gas phase
| Autor: | D. B. Jacobson, Ben S. Freiser |
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| Rok vydání: | 1984 |
| Předmět: | |
| Zdroj: | Journal of the American Chemical Society. 106:3891-3899 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | The gas-phase reactions of FeCH/sub 3//sup +/ and CoCH/sub 3//sup +/ with aliphatic alkanes up to C/sub 6/H3exclamation/sub 4/ were studied. FeCH/sub 3//sup +/ is completely unreactive with the aliphatic alkanes, while CoCH/sub 3//sup +/ reacts with all alkanes larger than ethane by initial insertion into a C-H bond resulting in CH/sub 4/ loss followed by dehydrogenation or alkane elimination forming Co(allyl)/sup +/ products. The Co(allyl)/sup +/ ions react rapidly with the alkanes (except methane) predominantly by dehydrogenation generating allyl-olefin complexes. The results indicate that the cobalt-allyl bond strength, D/sup 0/(Co/sup +/-C/sub 3/H/sub 5/), is in excess of 72 kcal/mol while D/sup 0/(Co/sup +/-butadiene) appears to be less than 52 kcal/mol. CoCH/sub 3//sup +/ also abstracts a hydride from alkanes larger than ethane (except for 2,2-dimethylpropane) forming C/sub n/ H/sub 2n + 1//sup +/ and implying D/sup 0/(CoCH/sub 3/-H/sup -/) = 256 +/- 10 kcal/mol which together with an earlier reported value of ..delta..H/sub f//sup 0/ (CoCH/sub 3/) = 256 +/- 4 kcal/mol yields D/sup 0/(CoCH/sub 4/) = 49 +/- 11 kcal/mol and ..delta..H/sub f//sup 0/ (CoCH/sub 4/) = 35 +/- 11 kcal/mol. Structures of the major primary product ions were investigated both by collision-induced dissociation (CID) and by specificmore » ion-molecule reactions. 32 references, 7 figures, 1 table.« less |
| Databáze: | OpenAIRE |
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