Cobalt carbonyl radicals and radical reactions of cobalt carbonyls

Associative Ligand Exchange and Substrate Activation Reactions by a Zero-Valent Cobalt Tetraisocyanide Complex

“…Since the first detection of Co­(CO) 4 by Keller and Wawersik using EPR spectroscopy in 1965 and its unequivocal matrix isolation by Poliakoff and Turner in 1974, a number of derivatives stemming from this zero-valent carbonyl have been generated via gas-phase reactions, including (O 2 )­Co­(CO) 3 , (PR 3 )­Co­(CO) 3 , and (η 2 - C,C - alkene)­Co­(CO) 3. − However, none of these complexes are long-lived enough for detailed spectroscopic or structural investigations, and the instability of Co­(CO) 4 has limited the exploration of its reactivity or mechanism of action with substrates in greater detail. While it is recognized that 17-electron transition-metal carbonyl radicals (e.g., V­(CO) 6 and M­(CO) 5 ; M = Mn, Re) undergo ligand substitution reactions ,− via a second-order associative mechanism, − no direct experimental studies have been carried out on Co­(CO) 4 and its simple ligand substitution pathways.…”

Reactions of early–late heterobimetallics with oxiranes: New examples for cooperative reactivity

“…Ref. [19]), a 7 type intermediate of the formation of 6 may be considered. Nevertheless, on the basis of our present experimental data, it is not possible to decide which type of precursors -6 or 7 or both -are formed when Method E was applied.…”

Outer sphere complexes as intermediates in coordination chemistry

“…A magnetic field effect on the ratio of the two products would be anticipated. A variety of other organometallic reactions which have been discussed in the recent literature [107][108][109][111][112][113] have similar mechanisms involving radical pairs.…”

“…Halpern [106] has recently discussed the occurrence of free radical mechanisms in catalytic hydrogenation and hydroformylation, in bioorganometallic chemistry, in oxidative addition, in reductive elimination and in insertion reactions. CIDNP studies in particular have demonstrated that many metal based reactions, which have long been thought to proceed by two electron transfers (as typified in the 16-18 electron rule) actually involve homolytic bond breaking to give radical pair intermediates [107][108][109][110][111][112][113]. Such intermediates are weak outer sphere metal complexes with lifetimes and structures which are probably determined by factors very similar to those encountered in other second sphere studies.…”