1517-51-7Relevant articles and documents
Deceptive Similarities in the Reactions of Fe+ and Co+ with Linear Nitriles in the Gas Phase
Lebrilla, Carlito B.,Drewello, Thomas,Schwarz, Helmut
, p. 5639 - 5644 (2007/10/02)
The gas-phase reactions of the transition-metal ions Fe+ and Co+ with linear C(4)-C(12) nitriles are reported.In spite of an overall similar reactivity pattern, a more detailed analysis, based on the study of labeled nitriles, reveals distinct differences with regard to the mechanisms of elimination of alkenes and alkanes.For both metal ions, hydrogen and alkenes are generated from linear C(4)-C(12) nitriles, and the intermediates are formed via oxidative addition to terminal and internal C-H bonds.For the RCN/Fe+ system insertion in an internal C-H bond commences at position C(8) of the nitrile; for the analogous RCN/Co+ system, the oxidative addition to an internal C-H bond starts at position C(7) of the nitrile.Similarly, alkane formation is different for the two transition-metal ions.For RCN/Fe+ the generation of alkanes is observed for nitriles having at least eight carbon atoms; in contrast, the elimination of alkanes from RCN/Co+ is already observed for C(6) nitriles.Alkane elimination seems to follow the conventional mechanism (i.e., oxidative addition to a C-C bond, β-hydrogen transfer, and reductive elimination) for the RCN/Co+ system, whereas for the RCN/Fe+ complex there exists an additional mechanism.This mechanism corresponds to the loss of H2 from an internal position of the alkyl chain followed by the elimination of an alkene.Some possible origins of the different behavior of Fe+ vs.Co+ are discussed.
The Collisionally Induced Dissociation of Allyl and 2-Propenyl Cations
Burgers, Peter C.,Holmes, John L.,Mommers, Alexander A.,Szulejko, Jan E.
, p. 596 - 600 (2007/10/02)
Pure (1+) and CH3C(1+)=CH2 ions are generated only in metastable fragmentations of 1+., X=Cl, Br, I, and 1+., X=Br, I, respectively.For ion source generated (1+) ions there is some structural interconversion.The structure characteristic feature of their collisional activation mass spectra is the ratio m/z 27 (1+):m/z 26 (1+.).For CH3C(1+)=CH2 the ratio is only weakly dependent upon the translational energy of the ion.For (1+), the ratio rises sharply as translational energy is reduced, from 0.9 at 8 kV to c. 3 at 1 kV. (1+) ions generated by charge reversal of (1-) show higher ratios, resulting from their lower average internal energy content.It must therefore be emphasized that (1+) ion structure assignments should only be made using reference data which apply to specific experimental conditions. (1+) daughter ion structures for a number of well-known fragmentations have been established.The heat of formation of the 2-propenyl cation was measured to be 969+/-5 kJ mol-1.Labelling experiments show that at low internal energies, allyl cations do not undergo atom randomization in c. 1-2 μs; high internal energy ions of longer lifetime (c. 8 μs) show complete atom randomization.H1+ atom loss from +. has been shown to generate (1+) and 13CH2=C(1+)-CH3 without any skeletal rearrangement.
