Ultraviolet laser photolysis: Primary photochemistry of Fe(CO)5 in PF3

Abstract

Articles you may be interested inTime-resolved infrared diode laser spectroscopy of the ν1 band of the iron carbonyl radical (FeCO) produced by the ultraviolet photolysis of Fe(CO)5We have studied the photolysis of mixtures of Fe(CO), and PF J with a KrF laser operating at 248 nm. The product yields of Fe(COh(PFJh. Fe(CO),(PFJh. and Fe(CO).PF J have been measured as a function of laser fluence and mixture composition. A simple kinetic model appears to explain semiquantitatively the observed dependence of product yield upon mixture composition. This model has allowed us to determine that the primary photochemical yields at 248 nm for the fragments Fe(COh, Fe(CO),. and Fe(CO). over the fluence range 0.1-200 mJ/cm 2 are 0.55. 0.35. and 0.10. respectively. independent of laser fluence. This fragmentation results from a simple one-photon absorption process. We have found that CO ligands are exchanged readily in collisions of the above fragments with Fe(CO),. with a bimolecular rate constant relative to that for trapping by PF J of kMlkT = 4. We have also found that these primary photofragments react with Fe(CO), to form unobserved products with a rate constant (relative to that for trapping by PF J ) of kQlkT = 7.

The mechanistic investigations of photochemical decarbonylations and oxidative addition reactions for M(CO)5 (M = Fe, Ru, Os) complexes

“…The available experimental observations show that upon COphotolysis of the pentacarbonyl metal complex M(CO) 5 , 2 it yields the coordinatively unsaturated intermediate, Fe(CO) 4 , which has the triplet ground state. This result has been veried both experimentally [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][48][49][50][51][52][53] and theoretically. [54][55][56][57][58][59][60][61] However, both Ru(CO) 4 and Os(CO) 4 are predicted to have a singlet ground state.…”

“…This theoretical observation is in good agreement with many experimental results. 2,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][33][34][35][36][37] For the Ru(CO) 5 and Os(CO) 5 model compounds, both ruthenium and osmium pentacarbonyls have similar photochemical and thermal potential energy proles. The computations also show that both Ru(CO) 4 and Os(CO) 4 fragments feature a singlet electronic ground state.…”

“…[11][12][13][14] is the most important aspect of its reaction to UV irradiation. [15][16][17][18][19][20][21][22][23][24][25] Starting from this unsaturated 16-electron iron carbonyl intermediate Fe(CO) 4 , it can easily react with different types of molecules to undergo oxidative addition reactions, [26][27][28] which are of both academic and commercial importance in inorganic and organometallic chemistry. [29][30][31][32] As a consequence, the study of the photochemistry of Fe(CO) 5 has been the subject of a great many experimental and theoretical studies that seek to determine the fundamental aspects of its reaction chemistry.…”

Photofragmentation of Transition Metal Cluster Complexes in the Gas Phase

“…These methods rely on ultraviolet (UV) laser photolysis followed by detection methods based on UV absorption (20), chemical trapping (21,22), IR absorption (23,24,25) and ionization (5,6,26,27).…”

Ultrafast laboratory-based x-ray sources and their applications in chemical research

“…In fact, single and multiphoton dissociation of transition metal carbonyls in the gas and liquid phase have been extensively studied by various spectroscopic methods [129][130][131][132][133][134][135][136][137][138][139][140][141][142][143] including transient light absorption spectroscopy. 143-150 It was found that in the gas phase several carbonyls could be lost upon photolysis of the complex with UVlight.…”