The Experts below are selected from a list of 2040 Experts worldwide ranked by ideXlab platform
Emile Biemont - One of the best experts on this subject based on the ideXlab platform.
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improved Atomic data for Iridium Atom ir i and ion ir ii and the solar content of Iridium
Journal of Quantitative Spectroscopy & Radiative Transfer, 2007Co-Authors: Sune Svanberg, Pascal Quinet, P Palmeri, Emile BiemontAbstract:From a combination of radiative lifetime measurements, performed with a time-resolved laser-induced fluorescence technique, for nine odd-parity levels of Ir I and four odd-parity levels of Ir II and branching fraction calculations, extended sets of transition probabilities have been derived for transitions of astrophysical interest. The new results are compared with the few experimental data available in the literature and a good agreement is found. They extend considerably the previous sets of transition probabilities available in the literature. Implications of the new results regarding the solar content of Iridium are briefly discussed.
Xuefeng Wang - One of the best experts on this subject based on the ideXlab platform.
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infrared spectra of ircch2 hircch and ir η2 c2h2 prepared in reaction of laser ablated Iridium Atom with acetylene
Journal of Physical Chemistry A, 2012Co-Authors: Qiang Wang, Xing Liu, Xuefeng WangAbstract:Laser-ablated Iridium Atom has been codeposited at 4 K with acetylene in excess argon. The vinylidene IrCCH(2), insertion product HIrCCH, and metallacycle complexes Ir-η(2)-(C(2)H(2)) and Ir-η(2)-(C(2)H(2))(2) are produced in present experiments and identified on the basis of the (13)C(2)H(2), C(2)D(2), and mixed C(2)HD isotopic substitutions and the comparison with theoretical predictions. The agreement between the experimental and calculated vibrational frequencies supports the identification of these molecules. Two alternative reaction mechanism of formation of Ir═C═CH(2) complex has been found on the potential energy surface of the studied system to account for the product formation. The conversion of acetylene to vinylidene on a Ir Atom is exothermic by 3.4 kcal/mol based on the B3LYP functional calculations.
Qiang Wang - One of the best experts on this subject based on the ideXlab platform.
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infrared spectra of ircch2 hircch and ir η2 c2h2 prepared in reaction of laser ablated Iridium Atom with acetylene
Journal of Physical Chemistry A, 2012Co-Authors: Qiang Wang, Xing Liu, Xuefeng WangAbstract:Laser-ablated Iridium Atom has been codeposited at 4 K with acetylene in excess argon. The vinylidene IrCCH(2), insertion product HIrCCH, and metallacycle complexes Ir-η(2)-(C(2)H(2)) and Ir-η(2)-(C(2)H(2))(2) are produced in present experiments and identified on the basis of the (13)C(2)H(2), C(2)D(2), and mixed C(2)HD isotopic substitutions and the comparison with theoretical predictions. The agreement between the experimental and calculated vibrational frequencies supports the identification of these molecules. Two alternative reaction mechanism of formation of Ir═C═CH(2) complex has been found on the potential energy surface of the studied system to account for the product formation. The conversion of acetylene to vinylidene on a Ir Atom is exothermic by 3.4 kcal/mol based on the B3LYP functional calculations.
Luís F. Veiros - One of the best experts on this subject based on the ideXlab platform.
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Energetics of the oxidative addition of I_2 to [Ir(Μ-L)(CO)_2]_2 (L=S^ t Bu, 3,5-Me_2pz,7-aza) complexes. X-ray structures of Ir(Μ-S^ t Bu)(I)(CO)_2]_2 and [Ir(Μ-3,5-Me_2pz)(I)(CO)_2]_2
Structural Chemistry, 1996Co-Authors: Miguel A. Ciriano, Luis A. Oro, Alberto R. Dias, Paulo M. Nunes, M. Fátima Minas Da Piedade, Manuel E. Minas Da Piedade, Palmira Ferreira Da Silva, José A. Martinho Simões, Jesús J. Pérez-torrente, Luís F. VeirosAbstract:The energetics of the oxidative additive of I_2 to [Ir( Μ -L)(CO)_2]_2 [L = t -buthylthiolate (S^ t Bu), 3,5-dimethylpyrazolate (3,5-Me_2pz), and 7-azaindolate (7-aza)] complexes was investigated by using the results of reaction-solution calorimetric measurements, X-ray structure determinations, and extended Hückel (EH) molecular orbital calculations. The addition of 1 mol of iodine to 1 mol of [Ir( Μ -L)(CO)_2]_2, in toluene, leads to [Ir( Μ -L)(I)(CO)_2]_2, with the formation of two Ir-I bonds and one Ir-Ir bond. The following enthalpies of reaction were obtained for this process: −125.8±4.9 kJ mol^−1 (L = S^ t Bu), −152.0±3.8 kJ mol^−1 (L=3,5-Me_2pz), and −205.9±9.9 kJ mol^¹ (L=7-aza). These results are consistent with a possible decrease of the strain associated with the formation of three-, four-, and five-membered rings, respectively, in the corresponding products, as suggested by the results of EH calculations. The calculations also indicate a slightly stronger Ir-Ir bond for L = 3,5-Me_2pz than for L= S^ t Bu despite the fact that the Ir-Ir bond lengths are identical for both complexes. The reaction of 1 mol of [Ir( Μ -S^ t Bu)(CO)_2]_2 with 2 mol of iodine to yield [Ir( Μ -S^ t Bu)(I)_2(CO)_2]_2 was also studied. In this process four Ir-I bonds are formed, and from the corresponding enthalpy of reaction (−186.4±2.7 kJ mol^−1) a solution phase Ir-I mean bond dissociation enthalpy in [Ir( Μ -S^ t Bu)(I)_2(CO)_2]_2, $$\overline {DH} _{\sin } (Ir - I) = 122.2 \pm 0.7 kJ mol^{ - 1} $$ , was derived. This value is lower than most $$\overline {DH} _{\sin } (Ir - I)$$ values reported for octahedral mononuclear Ir^111 complexes. New large-scale syntheses of the [Ir( Μ -L)(CO)_2]_2 complexes, with yields up to 90%, using [Ir(acac)(CO)_2] as starting material, are also reported. The X-ray structures of [Ir( Μ -L)(I)(CO)_2]_2 (L=S^tBu and 3,5-Me_2pz) complexes have been determined. For L=S^tBu the crystals are monoclinic, space group P2_l/c, a =10.741(2) å, b = 11.282(3) å,c=18.308(3) å, Β =96.71(1)‡, and Z =4. Crystals of the Μ -3,5-Me_2pz derivative are monoclinic, space group P2_l/n, a =14.002(3) å, b = 10.686(1) å, c =15.627(3) å, Β =112.406(8)‡, and Z =4. In both complexes the overall structure can be described as two square-planar pyramids, one around each Iridium Atom, with the iodine Atoms in the apical positions, and the equatorial positions occupied by two CO groups and the two sulfur Atoms of the S^ t Bu ligands, or two N Atoms of the pyrazolyl ligands. In the case of L=S^tBu the pyramids share a common edge defined by the two bridging sulfur Atoms and for L =3,5-Me_2pz they are connected through the two N-N bonds of the pyrazolyl ligands. The complexes exhibit short Ir-Ir single bonds of 2.638(1) å for L=S^tBu and 2.637(1) å for L=3,5-Me_2Pz. The oxidative addition of iodine to [Ir( Μ -3,5-Me_2pz)(CO)_2]_2 results in a remarkable compression of 0.608 å in the Ir-Ir separation.
Pascal Quinet - One of the best experts on this subject based on the ideXlab platform.
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improved Atomic data for Iridium Atom ir i and ion ir ii and the solar content of Iridium
Journal of Quantitative Spectroscopy & Radiative Transfer, 2007Co-Authors: Sune Svanberg, Pascal Quinet, P Palmeri, Emile BiemontAbstract:From a combination of radiative lifetime measurements, performed with a time-resolved laser-induced fluorescence technique, for nine odd-parity levels of Ir I and four odd-parity levels of Ir II and branching fraction calculations, extended sets of transition probabilities have been derived for transitions of astrophysical interest. The new results are compared with the few experimental data available in the literature and a good agreement is found. They extend considerably the previous sets of transition probabilities available in the literature. Implications of the new results regarding the solar content of Iridium are briefly discussed.
