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La reaction entre Fe(CO) 5 et des ions negatifs a lieu par addition nucleophile d'un anion produisant (CO) 4 FeC(O)X − , (CO) 4 FeX − , (CO) 3 FeX − . Mecanisme de ces reactions

Fe{sup {minus}} and Co{sup {minus}} are found to react with simple thiols, sulfides, and disulfides. The primary reaction products formed from these metal anions, M{sup {minus}}, and thiols include MS{sup {minus}}, MSH{sup {minus}}, and MSH{sub 2}{sup {minus}} and suggest a mechanism involving initial insertion of the metal into the weak C-S bond. Similarly, C-S insertion is the main mode of attack in the reactions with the sulfides and disulfides, in analogy to what is observed for the reaction of metal cations. Collision-induced dissociation is used to support the proposed structures for the primary products, H-Fe{sup {minus}}-SH and Fe{sup {minus}}-SH. Some of the thermochemical data derived from this study include D{degree}(M{sup {minus}}-S) > 103 kcal/mol and D{degree}(M{sup {minus}}-SH) = 83 {plus minus}9 kcal/mol. Finally, a brief survey of the reactivity of V{sup {minus}}, Cr{sup {minus}}, and Mo{sup {minus}} with selected organosulfur compounds is also reported. 79 refs., 3 figs., 7 tabs.

Reactions donnant plusieurs nouveaux exemples d'anions d'oxydes metalliques produits a temperature ordinaire. Nature radicalaire de l'oxydation primaire

A Fourier transform mass spectrometer utilizing collision-induced dissociation (CID) of anionic chromium (Cr) carbonyl complexes was used to study the gas-phase reactivity of the metal anion. Measurements are consistent with a relatively weak Cr-C bond in CrCO/sup -/ which reflects the inherent stability of the 3d/sup 5/4s/sup 2/ Cr/sup -/ fragment. Also, the chromium atom is relatively weakly bound in Cr/sub 2/(CO)/sub 5//sup -/ as shown by the loss of the metal ion from the complex when subjected to low-energy CID excitation. A Cr-H bond energy of 41.8 +- kcal mol/sup -1/ was calculated from the literature reported electron affinity of Cr(1.5 +- 0.2 kcal mol/sup -1/), ionization potential of hydrogen (313.6 kcal mol/sup -1/), and the authors' assigned proton affinity of Cr (340 +- 3 kcal mol/sup -1/). 2 figures, 1 table.