Kinetik und Mechanismus der Aminolyse von (Methoxyphenylcarben)pentacarbonylchrom(0) - Eine reaktion 4. Ordnung mit negativer Arrhenius-Aktivierungsenergie

摘要: Abstract The kinetics of the reaction (methoxyphenylcarbene)pentacarbonylchromium(0), Cr(CO)5C(OCH3)C6H5 (I), with primary amines RNH2 (R = n-C4C9, C6H11, CH2C6H5) have been studied in n-decane, dioxane, methanol and dioxane/methanol ( 1 ) as solvents. formation aminophenylcarbene complexes Cr(CO)5C(NHR)C6H5 (II) follows fourth-order rate law d[(II)]/dt KA·[(I)]·[RNH2]·[HX]·[Y] where HX represents a proton donating Y accepting agent. results kinetic studies are conistent consecutive step mechanism which starts -adduct carbene complex (I) donor includes activation attacking amine by acceptor Y. existence hydrogen bonds between HX, is shown NMR measurements. explains unexpected result that decreases increasing temperature, i.e. negative Arrhenius energy observed. mechanismsof aminolysis carboxylic esters (which may formally be considered very reactive analog an ester) compared. Mechanistic similarities differences will discussed.