(.eta.2-trans-Cyclooctene)2Fe(CO)3 and related complexes: structure and dynamic behavior

Bis(η2-cyclooctene)(N,N-dimethyldithiocarbamato-S,S′)iridium(I), the first example of a tetracoordinate IrIcomplex containing two π-bonded monoolefin ligands

“…The ±CÐC CÐC± fragments remain essentially planar after coordination, judging by the C4ÐC3Ð C10ÐC9 torsion angle of 5.3 (5) . The coordinated cyclooctene ligands adopt a crown-like conformation, similar to that previously observed in two cyclooctene complexes of iron (Angermund et al, 1988) and copper (Ganis et al, 1970).…”

Gas Phase Study of the Kinetics of Formation and Dissociation of Fe(CO)4L and Fe(CO)3L2 (L = C2H4 and C2F4)

“…This competition for electron density has also been invoked to explain the observed decrease in lifetime of iron carbonyl complexes as the number of olefins increases. There is a limited back-bonding capability of the metal, with more olefins drawing electron density from the same metal orbitals. , The olefins occupy in-plane equatorial sites when substituted in iron carbonyl, and as a result they compete with each other for electron density from the same metal orbitals.…”

“…This Fe(CO) 3 (C 2 H 4 )−C 2 H 4 bond energy is compared to previously determined bond dissociation energies for similar metal−olefin bonds. With the same metal center, the decreased stability of bisethylene-substituted species as compared to monoethylene-substituted compounds has been ascribed to an increase in olefin competition for metal electron density from common d orbitals. ,− With the same number of ethylene ligands, the iron compounds are more stable than the chromium compounds due to iron being more electron rich and therefore having more electron density available for back-bonding. There appears to be a reversal in the order of stability of the disubstituted compounds of C 2 H 4 and C 2 F 4 on going from chromium to iron, again explainable based on the relative electron density of the two metals.…”

“…There is a limited back-bonding capability of the metal, with more olefins drawing electron density from the same metal orbitals. 24,39 The olefins occupy in-plane equatorial sites when substituted in iron carbonyl, and as a result they compete with each other for electron density from the same metal orbitals.…”

Investigation of organometallic reaction mechanisms with one and two dimensional vibrational spectroscopy

“…is for the complex Fe(CO) 3 (η 4 -1,5-cyclooctadiene), the linear IR spectrum of which has been reported several times [233,[247][248][249][250][251]. Grevels, McClung, and coworkers modeled the changes in lineshape with temperature in terms of exchange and were able to extract rate constants for the exchange process by systematically fitting the spectra at multiple temperatures.…”