VOLUME114, NUMBER 8 APRIL8, 1992 0 Copyright 1992 by the American Chemical Society
JOURNAL OF THE AMERIG4N CHEMICAL SOCIETY Gas-Phase Reactions of Cr( CO)s-, Fe(C0)4-, and Ni(C0)3with Organic Electrophiles Ying H. Pan and Douglas P. Ridge* Contribution from the Department of Chemistry and Biochemistry and Center for Catalytic Science and Technology, University of Delaware, Newark, Delaware I971 6. Received April 1 , 1991
Abstract: Rate constants and product distributions for reactions of the title anions with 15 organic electrophiles as measured by Fourier transform ion cyclotron resonance techniques are reported. The electrophiles are all aromatic or olefinic compounds with electronegative substituents. The reaction efficiencies defined as the overall rate constant divided by the collision rate (klk,) vary from unity to unmeasurable (upper limit lo-' or less). For each anion reactivity drops rapidly as the electron affinity (EA) of the electrophile drops below some critical range values. The critical range (eV) is 0.624.91, 1.01-1.29, and 1.29-1.44 for Ni(CO) 1.46 eV) reacts efficiently by ligand substitution with Fe(C0)4- and Cr(CO)< which is consistent with the pattern observed in the present study. McDonald and Schell also report that TCNE reacts with Fe(CO),- and Cr(CO)5- by both outright charge transfer and ligand substitution. They are unable to obtain rate constants for the T C N E reactions, but the branching ratios obtained in the present study are in satisfactory agreement with theirs. They report a slow (k/k, = ca.lo-") ligand substitution reaction between biacetyl (EA = 0.69eV) and Cr(CO)
