A time-resolved infrared study of the gas-phase reactions of 1,3- and 1,4-pentadiene with iron carbonyls [Fe(CO)3 and Fe(CO)4]

A Novel Facet of Carbonyliron-Diene Photochemistry: The η4-s-transIsomer of the Classical Fe(CO)3(η4-s-cis-1,3-butadiene) Discovered by Time-Resolved IR Spectroscopy and Theoretically Examined by Density Functional Methods

“…It is worth mentioning in this context that the involvement of the s-trans conformer of a free 1,3-diene was not considered in related gas phase studies . Rather, photogenerated Fe(CO) 3 was suggested to add the 1,3-diene in the form of its s-cis conformer, yielding an ( s-cis -1,3-diene)-Fe(CO) 3 type complex as the only initially formed adduct.…”

Computational study of the energetics of3Fe(CO)4,1Fe(CO)4and1Fe(CO)4(L), L = Xe, CH4, H2and CO

“…[15][16][17][18] To provide support for the qualitative description of reactivity given above, it is important to be able to show that such NA-TST calculations can give near-quantitative agreement with experimental rate coefficients for spin-forbidden organometallic reactions. 19 Although relatively little experimental data of this type is available, one type of reaction, the gas phase addition of small molecules to triplet iron tetracarbonyl, has been studied extensively by Weitz et al [20][21][22][23][24][25][26][27][28] We have already shown 19 that NA-TST is able to predict the rate coefficient for addition of carbon monoxide to triplet Fe(CO) 4 to give singlet Fe(CO) 5 to within better than one order of magnitude, which is probably the best level of accuracy which can be expected using a statistical rate theory. This reaction 27,29 is roughly 500 times slower than the collisional rate, and we found that this is due partly to the fact that the MECP lies slightly (0.5 kcal mol À1 ) higher in energy than the reactants, and partly to the fairly low (5%) probability of surface hopping upon reaching the MECP.…”

A Gas-Phase Study of the Kinetics of Formation of Fe(CO)3DMB, Fe(CO)3(DMB)2, and Fe(CO)4DMB: The Bond Dissociation Enthalpy for Fe(CO)3(DMB)2 (DMB = 3,3-dimethyl-1-butene)

“…5,17 One factor that has been previously considered is the polarizability of the entering ligand. 17 Since a curve crossing must occur to produce stable products, a complex that has a longer lifetime on the triplet potential surface will, with all else Yes Fe(CO)3 + PD 29 (2.8 ( 0.3) × 10 -10 Yes Fe(CO)3 + propene 7 (2.6 ( 0.3) × 10 -10 Yes Fe(CO)3 + 1-pentene 8 (4 ( 1) × 10 -10 Yes Fe(CO)3(C2H4) + C2H4 15 (1.1( 0.3) × 10 -11 No Fe(CO)3(C2H4) + propene 7 (1.8( 0.3) × 10 -11 No Fe(CO)3(C2F4) + C2F4 9 (5. No Fe(CO)4 + 1,3-PD 29 (1.2( 0.1) × 10 -12 No Fe(CO)4 + 1,4-PD 29 (5.8( 0.3) × 10 -13 No Fe(CO)3(C2H4) + Fe(CO)5 9 (4( 2) × 10 -11 Fe(CO)3(C2Cl4) + Fe(CO)5 28 being equal, have a higher probability for curve crossing.…”

“…28 The methyl and methylene groups in DMB can "fold back" away from the Fe(CO) 3 DMB to minimize the steric interaction energy. Though there is no experimental evidence for formation of a stable iron carbonyl bis olefin complex with 1,3-PD or 1,4-PD, 29 the interaction energies with these ligands can still be evaluated. As anticipated, these species have modest interaction energies (∼50% of the value for DMB and ∼50% more than the value for ethylene) since the methyl and methylene groups can "fold back" away from the other ligands in the Fe(CO) 3 (PD) complex.…”