92940-66-4Relevant academic research and scientific papers
Reactions of Dienes with the Ion +: A Kinetic and Mechanistic Study of Complex Formation and Diene Hydrogenation
Howarth, Oliver W.,McAteer, Colin H.,Moore, Peter,Morris, George E.
, p. 1171 - 1180 (1984)
Stopped-flow n.m.r. reveals markedly different rates of co-ordination of cyclo-octa-1,5-diene (cod) and bicyclohepta-2,5-diene (norbornadiene, nbd) to the ion + (1). + ions are the first formed products.The interconversion of all three + isomers has been observed by 1H and 31P n.m.r. sprectroscopy.These species react further to give + (2), either by H2 elimination, or by hydrogenation of the co-ordinated nbd to form bicyclohept-2-ene (norbornene, nbe).Stopped-flow spectrophotometry reveals a marked inverse kinetic isotope effect for the formation of (2) during the hydrogenation or deuteriation of nbd.A mechanism involving an equilibrium between diene-dihydride and alkyl-hydride is proposed.The dienes 2,3-dimethylbutadiene and cyclohexa-1,3- or -1,4-diene react with (1) to give highly fluxional allyl-hydride species which feature an aliphatic C-H...IrIII interaction.Variable-temperature 1H and 31P n.m.r., and 1H spin-saturation transfer experiments reveal a facile reversible hydrogen-transfer process between metal and hydrocarbon ligand which occurs via a C-H...IrIII interaction.
