71564-30-2Relevant articles and documents
Gas phase study of the kinetics of formation and dissociation of Fe(CO)4L and Fe(CO)3L2 (L = C2H4 and C2F4)
House, Paul G.,Weitz, Eric
, p. 2988 - 2995 (2007/10/03)
The bond dissociation energy for loss of C2H4 from Fe(CO)3(C2H4)2, produced by the reaction of C2H4 + Fe(CO)3(C2H4), has been determined as 21.3 ± 2.0 kcal/mol. An estimate is made for a lower limit for the bond dissociation energy of Fe(CO)4(C2H4), which can be formed by reaction of CO + Fe(CO)3(C2H4) or Fe(CO)4 + C2H4 with rate constants of (4.3 ± 0.8) × 10-12 and (1.7 ± 0.2) × 10-13 cm3/(molecule s) at 24 °C, respectively. The values for these bond dissociation energies are compared with those determined in prior studies of these systems. A new compound with infrared absorptions at 2147, 2091, and 2068 cm-1 is best assigned as Fe(CO)3(C2F4)2. A rate constant of (5.4 ± 1.7) × 10-12 cm3/(molecule s) at 24°C is reported for the reaction of C2F4 with Fe(CO)3(C2F4) to form Fe(CO)3(C2F4)2. Fe(CO)4(C2F4) can be formed by reaction of C2F4 and Fe(CO)4, with a rate constant of (1.8 ± 0.4) × 10-14 cm3/(molecule s) at 24°C. Infrared absorptions observed at 2135, 2074, and 2043 cm-1 are assigned to this species. The relative stabilities of the mono- and bisethylene and perfluoroethylene compounds of iron are compared. Where possible, they are also compared to the corresponding chromium compounds and are discussed in the context of current concepts regarding metal-olefin bonding.
A transient infrared spectroscopy study of coordinatively unsaturated osmium carbonyl compounds
Bogdan, Paula L.,Weitz, Eric
, p. 639 - 644 (2007/10/02)
Transient infrared spectroscopy is used to study the coordinatively unsaturated osmium carbonyl fragments generated by 248-nm photolysis of gas-phase Os(CO)5. The nascent photoproducts, predominantly Os(CO)3 with some Os(CO)4, are highly reactive toward combination with both CO and Os(CO)5. The bimolecular rate constants for reaction of Os(CO)3 and Os(CO)4 with CO are 7.6 ± 0.9 and 5.5 ± 0.6 × 10-11 cm3 molecule-1 s-1, respectively. Infrared absorptions for a new unsaturated osmium species, Os2(CO)8, formed by reaction of Os(CO)3 with Os(CO)5, are assigned. The rate constant for this reaction is 2.7 ± 0.9 × 10-10 cm3 molecule-1 s-1, on the order of gas kinetic. The reactivities of the unsaturated osmium species are similar to those of the analogous ruthenium compounds and contrast with the reactivity of Fe(CO)4. The trends observed in the photochemistry of group 8 metal carbonyl complexes and the role of spin selection rules in the reactivity of these coordinatively unsaturated fragments are discussed. Continuing depletion of the Os(CO)5 parent after photolysis indicates that polynuclear osmium carbonyl clusters are formed.
Gas-phase ligand substitution reactions with the 17-electron transition-metal complexes (OC)4Fe.-, (OC)5Cr.-, and (OC)4MnH.-
McDonald, Richard N.,Schell, Philip L.
, p. 1820 - 1827 (2008/10/08)
Three transition-metal complex negative ions, (OC)4Fe.-, (OC)5Cr.-, and (OC)4MnH.-, were generated and studied in ligand substitution reactions with a variety of neutral ligand substrates. Only (OC)4Fe.- reacted with PF3 and gave sequentially the product ions (OC)4-xFe(PF3)x.- where x = 1-3. The three metal complex negative ions formed ligand substitution product anions with NO; the reaction with (OC)4MnH.- also produced some of the corresponding adduct anion. With SO2, (OC)4Fe.- gave only ligand substitution, (OC)5Cr.- formed a mixture of the adduct and the product of ligand substitution, and (OC)4MnH.- produced only the adduct. Both the NO and SO2 reactions were believed to occur by the associative mechanism with the SO2 reactions proceeding via Lewis acid-base complexes. Only (NC)2C=C(CN)2 (TCNE) of the seven olefins examined reacted with the metal complex negative ions forming the product of electron transfer (TCNE.-) as well as the product ions of ligand substitution. The reactions of all three metal complex negative ions with (CF3)2C=O and of (OC)5Cr.- with biacetyl were considered to involve initial electron transfer within the orbiting collision complex. The reaction of (OC)4MnH.- with O2 produced various oxidation products, the most noteworthy being HCO2- as a major product anion. This latter result is considered to be evidence for the migratory insertion reaction, OC-Mn-H ? Mn-CHO, in the adduct formed from (OC)4MnH.- with O2.
