Is the Fe + ‐Induced C — H/C — C Bond Activation of α,ω‐Alkanedinitriles Affected by Bifunctional Interactions?

The metastable‐ion mass spectra of Fe + complexes of alkanedinitriles NC(CH 2 ) n CN ( n = 1 – 10) exhibit six types of reactions: ( 1 ) Loss of the intact ligand to regenerate bare Fe + as the exclusive ( n = 1) or major reaction ( n = 2) for the lower homologues; (2) generation of nitriles H(CH 2 ) m CN with m = 0 – 6; (3) formation of unsaturated nitriles CH 2 = CH(CH 2 ) m CN with m = 0 – 4; ( 4 ) production of C 2 H 4 ; (5) dehydrogenation, and (6) expulsion of the radicals C 2 H 5 and CH 2 CN + . The branching ratios of these competing processes are governed by the chain length (CH 2 ) n separating the two CN groups. Mechanistic insight is provided by the study of isotopomers. A comparison of the present data with the previously described behaviour of RCN/Fe + complexes (R = alkyl) leaves no doubt that for the α,ω‐alkanedinitriles it is the Fe + ‐mediated interaction of the two functional groups which controls the gas‐phase chemistry of these organometallic systems. For example, results are presented demonstrating inter alia that losses of H 2 and C 2 H 4 proceed by completely different pathways when dinitriles serve as precursors, and either reaction is affected by neighbouring group participation. In distinct contrast, for RCN/Fe + complexes (R = alkyl) the existing data point to common intermediates.