15684-00-1Relevant articles and documents
Synthesis and Characterization of the Pentacarbonylmanganese(0) Radical, Mn(CO)5, in Low-Temperature Matrices
Church, Stephen P.,Poliakoff, Martyn,Timney, John A.,Turner, James J.
, p. 7515 - 7520 (1981)
Mn(CO)5 has been synthesized by UV photolysis of HMn(CO)5 in solid CO matrices at 10 - 20 K.The HCO radical is also produced.A combination of 13CO enrichment and IR spectroscopy shows that Mn(CO)5 has a square-pyramidal, C4v, structure with an axial-equatorial bond angle of 96 +/- 3 grad.Mn(CO)5 has a weak visible absorption (λmax = 798 nm), close to the absorption reported for Mn(CO)5 generated in ethanol solution by pulse radiolysis.Photolysis with plane-polarized UV light has been used to unravel some of the complexities in the IR spectrum and to show that the UV absorption of Mn(CO)5 in the region 300 - 340 nm has a transition moment of e symmetry.
Rate constants for reactions of Cl abstraction from CCl4 by CCl3CH2 .CHR radicals and Br abstraction from CCl3CH2CHBrR (R = Bun, AcO, OCNC4H8, CN) by .
Gasanov
, p. 46 - 49 (2007/10/03)
The rate constants for reactions of Cl abstraction from CCl4 by CCl3CH2 .CHR radicals and Br abstraction from CCl3CH2CHBrR (R = Bun, AcO, OCNC4H8, CN) by s
Matrix infrared spectra and density functional calculations of manganese and rhenium carbonyl neutral and anion complexes
Andrews, Lester,Zhou, Mingfei,Wang, Xuefeng,Bauschlicher Jr., Charles W.
, p. 8887 - 8897 (2008/10/08)
The reaction of laser-ablated Mn and Re atoms and electrons with CO upon co-condensation in excess argon and neon generated the carbonyl neutral and anion complexes. These species were identified via density functional theory isotopic frequency calculatio
Photochemical bond homolysis in a novel series of metal-metal bonded complexes Ru(E)(E′)(CO)2(iPr-DAB)
Aarnts, Maxim P.,Stufkens, Derk J.,Vlcek Jr., Antonin
, p. 37 - 46 (2008/10/08)
Photochemistry of the complexes trans,cis-Ru(E)(E′)(CO)2(iPr-DAB) (E = Cl, SnPh3, PbPh3, Mn(CO)5, Re(CO)5, Me; E′ (depending on E) = SnPh3, PbPh3, GePh3, Mn(CO)5, Re(CO)5) was found to be strongly dependent on the combination and characters of the axial ligands E and E′. Except for Ru(Cl)(SnPh3)(CO)2(iPr-DAB) and Ru(Cl)(PbPh3)(CO)2(iPr-DAB) which are nearly unreactive, one of the Ru-E/E′ bonds is split homolytically upon irradiation into the lowest-energy absorption band of the complex. For Ru(SnPh3)2(CO)2(iPr-DAB), this reaction occurs from a thermally equilibrated 3σπ* excited state with a rate constant of 2.3 × 105 s-1 and a temperature-dependent quantum yield (Ea = 1450 cm-1). The unselective Ru-Ge (60%) and Ru-Sn (40%) bond homolysis of Ru(SnPh3)(GePh3)(CO)2-(iPr-DAB) follows the same mechanism. On the other hand, bond homolysis is much faster (?108 s-1) for complexes which contain Ru-Me, Ru-Mn or Ru-Re bonds. Bond homolysis in these species is highly selective, since only Ru-Me, Ru-Mn and Ru-Re bond splitting was observed for Ru(Me)(SnPh3)(CO)2(iPr-DAB), Ru(SnPh3)(Mn(CO)5)(CO)2(iPr-DAB) and Ru(SnPh3)(Re(CO)5)(CO)2(iPr-DAB), respectively. The photoproduced [Ru(E)(CO)2(iPr-DAB)]· radicals were detected by time resolved UV-Vis spectroscopy on a timescale 10 ns-100 μs. The [Ru(SnPh3)(CO)2(iPr-DAB)]· radical was also characterised by EPR in the form of its adduct with PPh3. Depending on the solvent used, they either dimerise or abstract a chlorine atom from the solvent to produce Ru(Cl)(E)(CO)2(iPr-DAB).
Properties and dynamics of the σ(M′-Re) π* excited state of photoreactive dinuclear LnM′-Re(CO) 3 (α-diimine) (LnM′ = Ph3Sn, (CO)5Mn, (CO)5Re; α-diimine = bpy′, iPr-PyCa, iPr-DAB) complexes studied by time-resolved emission and absorption spectroscopies
Rossenaar, Brenda D.,Lindsay, Elspeth,Stufkens, Derk J.,Vl?ek Jr., Antonín
, p. 5 - 14 (2008/10/08)
The photophysics and photochemistry of the metal-metal bonded complexes LnM′Re(CO)3(α-diimine) (LnM′ = Ph3Sn, (CO)5Re, (CO)5Mn; α-diimine = bpy′, iPr-PyCa, iPr-DAB) have been studied. According to the time-resolved emission (80 K) and absorption (room temperature) spectra, the lowest excited state has a 3σ (M′-Re) π* character. It is a bound state, which can only be populated by surface crossing from optically excited MLCT states. Homolysis of the metal-metal bond from the σπ* state is promoted by nucleophilic and chlorinated solvents. Exceptional in this respect is the complex Ph3SnRe(CO)3(bpy′), which is nearly photostable in non-chlorinated solvents. The lifetime of the 3σπ* state decreases in the order α-diimine = bpy′ > iPr-PyCa > iPr-DAB > pAn-DAB. This trend is mainly determined by the energy gap law. The LnM′ dependence is more complicated because of an additional deactivating effect of an excited state distortion which depends on LnM′. At 80 K, the lifetime is determined by the weak coupling to the ground state; at room temperature by dissociation of M′-Re (with the exception of Sn-Re).
RHENIUM CARBONYL AND DINITROGEN COMPLEXES: IDENTIFICATION OF INTERMEDIATES BY MATRIX ISOLATION PHOTOCHEMISTRY AND METAL ATOM SYNTHESIS
Klotzbuecher, W. E.
, p. 5 - 10 (2007/10/02)
Mono- and dinuclear rhenium species were produced by irradiation of Re2(CO)10 in inert and reactive matrices and by direct synthesis of novel compounds via cocondensation of rhenium atoms with prospective ligands (N2, O2, 13CO, C2H4, H2O).Subtle differenc
Spin Trapping with Thiocarbonyl Compounds
Alberti, Angelo,Benaglia, Massimo,Bonini, Bianca F.,Pedulli, Gian Franco
, p. 3347 - 3358 (2007/10/02)
A wide variety of radicals has been added to three relatively stable thiocarbonyl compounds, namely thiobenzoyltriphenylsilane (TBTPS), 2,4,6-tri-t-butylthiobenzaldehyde (TBTBA), and tris(trimethylsilyl)ethanethial or trisylthioaldehyde (TSTA), in order to test their ability to act as radical scavengers and the possibility of using them as spin-trapping agents.Reactions with radicals centred at elements from Groups IV to VI afforded in all cases persistent spin adducts which were studied by e.s.r. spectroscopy.In particular the adducts with TBTPS showed well resolved e.s.r. spectra for which the hyperfine pattern allowed in most cases an unambiguous identification of the trapped radical.The decay of some of the TBTA and TSTA adducts has been monitored, and the rate constants for the process determined.The rate of addition of the t-butoxyl and pivaloyl radicals to TSTA were also measured as (1.2+/-0.5)x107 and (1.9+/-0.5)x106 dm3 mol-1 s-1, respectively.
Laser photolysis study of dirhenium decacarbonyl: Evidence for a nonradical primary process
Yasufuku, Katsutoshi,Noda, Hisanao,Iwai, Jun-Ichi,Ohtani, Hiroyuki,Hoshino, Mikio,Kobayashi, Takayoshi
, p. 2174 - 2176 (2008/10/08)
The photochemistry of Re2(CO)10, in cyclohexane was investigated by nanosecond laser flash photolysis (355-nm excitation). Experimental results verified that there are two photodissociation processes: one the well-known metal-metal bond scission to produce ·Re(CO)5 and the other the newly found nonhomolytic process of dissociative CO loss. The CO dissociation process is more dominant in the photolysis of Re2(CO)10 than in that of Mn2(CO)10.
