Observation of coordinatively unsaturated intermediates following the pulsed UV photolysis of iron pentacarbonyl (Fe(CO)5)

The Spectroscopy and Reaction Kinetics of Coordinated Unsaturated Metal Carbonyls.

“…With the above technique, we have been able to obtain the first gas phase infrared spectrum of a coordinatively unsaturated metal. 1 We have obtained infrared spectra in the CO stretch region for the species Fe(CO)x (x = 2,3,4) and have measured the rate of reaction of Fe(CO)x with CO and the activation energies for these reactions. 2 We have made the first real time observation of and are measuring the kinetics for clustering of Fe(CO) x species.…”

FTIR Studies of Iron–Carbonyl Intermediates in Allylic Alcohol Photoisomerization

“…[1][2][3][4][5] By far, iron-pentacarbonyl ([Fe(CO) 5 ]) has been the precursor of choice for photoisom-A C H T U N G T R E N N U N G erization, and in the case of allylic alcohols, aldehydes or aldol products are produced irreversibly upon tautomerization. [6][7][8][9][10][11] While the proposed active catalyst [Fe(CO) 3 ] and key intermediate [FeH(CO) 3 A C H T U N G T R E N N U N G (allyl)] have been observed mainly under low-temperature matrix or gas-phase conditions [1] and a computational study on the mechanism of iron-carbonyl-mediated isomerization of allylic alcohols to saturated carbonyls has been carried out, [6] more convincing evidence to support the catalytic photoisomerization of allylic alcohols could be obtained if some of these intermediate species could be detected directly during the room-temperature process itself with low catalytic loading.…”

“…4 A C H T U N G T R E N N U N G (R-C 3 H 4 OH)], and more importantly the p-allyl iron-carbonyl hydride species 3 A C H T U N G T R E N N U N G (R-C 3 H 3 OH)] was also generated indicating the common occur…”

“…As [Fe(CO) 4 A C H T U N G T R E N N U N G (C 3 H 5 OH)] does not absorb in the 532 nm region, it is unlikely that this species will further dissociate to yield [Fe(CO) 3 ], presumably the active catalytic species. [2,14] However the direct formation of [Fe(CO) 3 ] from [Fe 3 (CO) 12 ] might account for the production of the 16-electron [Fe(CO) 3 A C H T U N G T R E N N U N G (C 3 H 5 OH)] species, which in turn undergoes rapid intramolecular rearrangement to form the 18-electron p-allyl iron hydride species [FeH(CO) 3 A C H T U N G T R E N N U N G (C 3 H 4 OH)] species. [6] Unfortunately we have failed to observe any IR signals attributable to [FeH(CO) 3 Table 1.…”

“…[2,14] However the direct formation of [Fe(CO) 3 ] from [Fe 3 (CO) 12 ] might account for the production of the 16-electron [Fe(CO) 3 A C H T U N G T R E N N U N G (C 3 H 5 OH)] species, which in turn undergoes rapid intramolecular rearrangement to form the 18-electron p-allyl iron hydride species [FeH(CO) 3 A C H T U N G T R E N N U N G (C 3 H 4 OH)] species. [6] Unfortunately we have failed to observe any IR signals attributable to [FeH(CO) 3 Table 1. [1] As mentioned earlier, the concentration of this Selected values from reference [1] 4 www.chemeurj.org species was based on the extinction coefficient values derived from [Fe(CO) 4 A C H T U N G T R E N N U N G (C 3 H 6 )].…”