Collect. Czech. Chem. Commun. 1999, 64, 1770-1779

Determination of the Nucleophilicity of Tricarbonyliron Coordinated Cyclohepta-1,3,5-triene

Herbert Mayr* and Karl-Heinz Müller

Institut für Organische Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), D-81377 München, Germany


The kinetics of the electrophilic additions of four diarylcarbenium ions (4a-4d) to tricarbonyl(η4-cyclohepta-1,3,5-triene)iron (1) have been studied photometrically. The second-order rate constants match the linear Gibbs energy relationship log k20 °C = s(E + N) and yield the nucleophilicity parameter N(1) = 3.69. It is concluded that electrophiles with E ≥ -9 will react with complex 1 at ambient temperature.

Keywords: Carbocations; Carbocycles; Iron; Kinetics; Linear free energy relationships; Electrophilicity.