56110-59-9

Upstream product

• 199620-14-9 chromium⁽⁰⁾ hexacarbonyl 
• 7783-55-3 trifluorophosphane 
• 18461-41-1 ((chloro)3phosphane)pentacarbonylchromium 

Relevant academic research and scientific papers

Branching ratios and bond dissociation energies from the excimer laser photolysis of group 6 metal carbonyls

Photolysis of the group 6 (Cr, Mo, W) metal carbonyls in the gas phase, at excimer laser wavelengths, may lead to more than one primary product.Branching ratios between these products have been measured as a function of photolysis wavelength, buffer gas pressure, and temperature using time-resolved infrared spectroscopy.The results are modeled using a sequential dissociation mechanism in which branching ratios are determined by competition between unimolecular dissociation and collisional relaxation.The sensitivity of the results to thermochemical input parameters and assumptions concerning energy disposal mechanisms is discussed.Under qualified assumptions the branching ratio measurements provide estimates for CO bond dissociation energies for coordinatively unsaturated metal carbonyls.For Mo and W the individual bond dissociation energies are close to the average values but for Cr the first three ligands coordinated are significantly less strongly bound than the last three.This finding is discussed in terms of recent ab initio calculations on bonding in metal carbonyls.

Excimer Laser Photolysis of Group 6 Metal Carbonyls in the Gas Phase

The excimer laser photolysis of Mo(CO)6 in the gas phase has been studied at 351, 308, 248, and 222 nm with laser-based, time-resolved infrared absorption spectroscopy.Results have also been obtained on the 308- and 222-nm photolysis of Cr(CO)6 and on the 222-nm photolysis of W(CO)6, complementing earlier studies and presenting a complete picture of group 6 metal carbonyl ultraviolet photodecomposition.Infrared spectra in the range 1700-2033 cm-1 have been assigned for the coordinatively unsaturated species Mo(CO)5, Mo(CO)4, and Mo(CO)3.As in the case of Cr and W,their gas-phase structures are the same as found in low-temperature matrices.Rates for the reaction of these species with CO and Mo(CO)6 have been determined and are fast, within ca 1/10th gas kinetic.Overall, the behavior of Mo(CO)6 is similar to the other group 6 carbonyls.The photolysis wavelength dependence of the fragmentation patterns in the group 6 carbonyls shows no correlation with initially excited electronic excited states of M(CO)6 but is consistent with a sequential dissociation proceeding entirely through ground electronic states of M(CO)x following rapid internal conversion of the initially populated state of M(CO)6.The relative fragment yields support earlier indications that in Cr(CO)6 the first M-CO bond dissociation energy, BDE6, is of the order of or smaller than the second (BDE5).The first case of buffer gas pressure dependence of the relative yields of M(CO)x and M(CO)x-1 fragments has been observed for x=5 following the 308-nm photolysis of Cr(CO)6.The form of the dependence can be modeled by unimolecular reaction theory with BDE6 = BDE5 = 36 kcal mol-1.

Photodissociation of Cr(CO)6 in a molecular beam at 248 nm: Observation of primary and secondary photoproducts by mass spectrometry

Photodissociation of Cr(CO)6 induced by a KrF* excimer laser (248 nm) was examined under molecular beam conditions, using a quadrupole mass spectrometer with electron impact ionization (11-19 eV) to detect the products as their respective ions.The ions of all Cr(CO)x products (x=0-5) were produced upon photodissociation of Cr(CO)6 at laser fluences from 1 to 10 mJcm-2.The quantitative behaviour of the Cr(CO)+x product ion yields vs laser fluence as well as statistical rate calculations indicate that Cr(CO)4 is the major product formed upon single-photon dissociation of Cr(CO)6 under collisionless conditions at 248 nm.The additional Cr(CO)+x (x5mJcm-2, secondary photodissociation of Cr(CO)4 becomes important.Cr(CO)2 is assigned as the major photoproduct formed via secondary photodissociation of Cr(CO)4.

Recombination of Cr(CO)n with CO: Kinetics and Bond Dissociation Energies

The pressure dependence of the recombination kinetics of Cr(CO)5 and Cr(CO)4 with CO has been studied with the technique of time-resolved infrared laser absorption spectroscopy.The high pressure limiting rate constants are 2.1 X 106 and 7.5 X 1

Studies on the Photochemistry of Chromium Hexacarbonyl in the Gas Phase: Primary and Secondary Processes

The photochemistry of Cr(CO)6, induced by pulsed laser excitation at 249 nm, has been studied with time resolved infrared laser absorption spectroscopy.This method allows us to determine the temporal evolution of the reactant and all major product species.We find that photoactivated Cr(CO)6 decays to yield Cr(CO)5 and CO.The CO product is translationally as well as ro-vibrationally excited.The Cr(CO)5 product is formed with sufficient internal energy to undergo rapid dissociation, yielding Cr(CO)4 and CO.Both decarbonylation reactions occur within 10-7 s of the photoactivation laser pulse.Cr(CO)4 reacts with Cr(CO)6 at a rate of 1.8 (+/-0.3) x 107 torr-1 s-1, yielding Cr2(CO)10.This binuclear complex has a lifetime of at least 10-3 s under our experimental conditions.Cr(CO)4 reacts with CO to form Cr(CO)5 at a rate of 1.4 (+/-0.2) x 106 torr-1 s-1.Cr(CO)5 reacts with CO to form Cr(CO)6 at a rate of 1.2(+/-0.2) x 106 torr-1 s-1.

PHOTOFRAGMENTATION DYNAMICS OF Cr(CO)6 IN THE GAS PHASE.

CO laser absorption spectroscopy has been used to study the dissociation dynamics of Cr(CO)//6 following photoactivation. Results suggest that the excited state prepared at 249 nm yields CO both by rapid predissociation, with an efficiency phi //S less than equivalent to 0. 36, and by intersystem crossing to a long-lived triplet, with an efficiency phi //T greater than equivalent to 0. 64. The triplet state thus formed undergoes serial decarbonylation yielding Cr(CO)//5 and Cr(CO)//4. Refs.

Medium Effects on the Photodissociation of Cr(CO)6

Medium effects on the photofragmentation of Cr(CO)6 are investigated to explain differences in the photochemistry occuring in gas and condensed phases.Results of two experiments are reported: (a) Collisional effects on the gas-phase photodissociation of Cr(CO)6 are investigated by multiphoton spectroscopic techniques. (b) Solution flash photolysis experiments on the picosecond time scale are reported.The primary photoproduct in condensed phase is Cr(CO)5, observed within 25 ps.

Metal Carbonyl Photochemistry. Part 1. Photolysis of the Group 6 Hexacarbonyls in Hydrocarbon Glasses; the Species M(CO)5, M(CO)4, M(CO)3, and

Photolysis of the Group 6 metal hexacarbonyls in hydrocarbon glasses at 80 K gives rise to species M(CO)n (n=3-5), presumably weakly solvated, by successive CO loss.Primary and subsequent processes both show photoreversal.Slow warming leads to recombinati