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Photolysis of PCl <sub/>3</sub> /POCl <sub/>3</sub> with Oxygen Dopant Using 193?nm ArF Excimer at Low Temperatures: Oxygen Insertion through ‘Phosphadioxirane’ Pathway
摘要： Photolysis was performed on PCl3 and POCl3 in the presence of oxygen dopant in Ar matrix at low temperatures using 193 nm ArF excimer laser. The photo irradiation initially facilitated the formation of ozone in situ in the low temperature matrix. For PCl3 + O2 photolysis with 193 nm ArF excimer, initially POCl3 was produced and subsequent oxygen atom insertion on POCl3 generated PO2Cl3. Furthermore, secondary reaction channel opens up in PCl3 + O2 photolysis to form a variety of photoproducts such as POCl, PIIIO2Cl, PVO2Cl and PO3Cl. The insertion of oxygen atom on POCl through phosphadioxirane intermediate generated PIIIO2Cl and the direct oxygen atom addition resulted in PVO2Cl. A successive oxygen insertion on PVO2Cl triggered the PO3Cl generation. The identification of all the photoproducts was confirmed through 18O2 isotopic experiments and quantum chemical computations performed using density functional theory (DFT). Computations carried out at B3LYP level of theory with 6–311 + + G(d,p) basis set were used to correlate the structure of photo products obtained experimentally. Interestingly, photo irradiation of POCl3 with oxygen dopant in Ar matrix @193 nm ArF excimer resulted in the generation of PO2Cl3, PO3Cl3 and PO4Cl3 photo products by a sequential insertion of oxygen atoms through phosphadioxirane intermediate. A compelling evidence for the passage of the reaction through phosphadioxirane intermediate is established through 18O2 isotopic substitution experiments.
关键词： DFT computations,matrix isolation,infrared spectroscopy,photolysis,phosphadioxirane intermediate
更新于2025-09-23 15:23:52
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Infrared Spectra of the HAnX and H <sub/>2</sub> AnX <sub/>2</sub> Molecules (An=Th and U, X=Cl and Br) in Argon Matrices Supported by Electronic Structure Calculations
摘要： Uranium and thorium hydrides are known as functional groups for ligand stabilized complexes and as isolated molecules under matrix isolation conditions. Here, the new molecular products of the reactions of laser-ablated U and Th atoms with HCl and with HBr, namely HUCl, HUBr and HThCl, HThBr, based on their mid and far infrared spectra in solid argon, are reported. The assignment of these species is based on the close agreement between observed and calculated vibrational frequencies. The H–U and U–35Cl stretching modes of HUCl were observed at 1404.6 and 323.8 cm?1, respectively. Using DCl instead to form DUCl gives absorption bands at 1003.1 and 314.7 cm?1. The corresponding bands of HThCl are 1483.8 (H–Th) and 1058.0 (D–Th), as well as 340.3 and 335.8 cm?1 (Th–35Cl), respectively. HUBr is observed at 1410.6 cm?1 and the BP86 computed shift from HUCl is 6.2 cm?1 in excellent agreement. The U–H stretching frequency increases from 1383.1 (HUF), 1404.6 (HUCl), 1410.6 (HUBr) to 1423.6 cm?1 (UH) as less electronic charge is removed from the U–H bond by the less electronegative substituent. These U–H stretching frequencies follow the Mayer bond orders calculated for the three HUX molecules. A similar trend is found for the Th counterparts. Additional absorptions are assigned to the H2AnX2 molecules (An = U, Th, X = Cl, Br) formed by the exothermic reaction of a second HX molecule with the above primary products.
关键词： infrared,matrix isolation,thorium,uranium,density functional calculations
更新于2025-09-23 15:22:29
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Photosensitive Tin Sulfur Dioxide Complexes with Unexpected Bonding Modes
摘要： Infrared spectra of the matrix isolated Sn(η2-O2S), Sn(η2-OSO), Sn(η2-O2S)(η1-OSO), Sn(η2-O2S)2, OSn2(η2-SO) and Sn(μ2-O2)SnS molecules were observed following laser-ablated Sn atoms reactions with SO2 during condensation in solid argon. The assignments for the major vibrational modes were confirmed by appropriate S18O2 and 34SO2 isotopic shifts, and density functional vibrational frequency calculations (B3LYP and BPW91). Interestingly, the mononuclear complexes are interconvertible; that is, irradiation induces the isomerization of Sn(η2-O2S) and Sn(η2-O2S)(η1-OSO) to Sn(η2-OSO) and Sn(η2-O2S)2, respectively, and vice versa on annealing. However, there is no evidence of isomerization reaction in between the binuclear molecules OSn2(η2-SO) and Sn(μ2-O2)SnS. Bonding in these products is discussed, and the electronic structures change associated with different bonding types are revealed which is crucial for the observed photochemical reactions.
关键词： Quantum chemical calculation,Matrix-isolation,Reactive intermediate,Infrared spectra,Reaction mechanism
更新于2025-09-19 17:15:36
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Chloro- and Dichloro-methylsulfonyl Nitrenes: Spectroscopic Characterization, Photoisomerization, and Thermal Decomposition
摘要： Chloro- and dichloro-methylsulfonyl nitrenes, CH2ClS(O)2N and CHCl2S(O)2N, have been generated from UV laser photolysis (193 and 266 nm) of the corresponding sulfonyl azides CH2ClS(O)2N3 and CHCl2S(O)2N3, respectively. Both nitrenes have been characterized with matrix-isolation IR and EPR spectroscopy in solid N2 (10 K) and glassy toluene (5 K) matrices. Triplet ground-state multiplicity of CH2ClS(O)2N (|D/hc| = 1.57 cm?1 and |E/hc| = 0.0026 cm?1) and CHCl2S(O)2N (|D/hc| = 1.56 cm?1 and |E/hc| = 0.0042 cm?1) has been confirmed. In addition, dichloromethylnitrene CHCl2N (|D/hc| = 1.57 cm?1 and |E/hc| = 0 cm?1), formed from SO2-elimination in CHCl2S(O)2N, has also been identified for the first time. Upon UV light irradiation (365 nm), the two sulfonyl nitrenes R–S(O)2N (R = CH2Cl and CHCl2) undergo concomitant 1,2-R shift to N-sulfonlyamines R–NSO2 and 1,2-oxygen shift to S-nitroso compounds R–S(O)NO, respectively. The identification of these new species with IR spectroscopy is supported by 15N labeling experiments and quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) level. In contrast, the thermally-generated sulfonyl nitrenes CH2ClS(O)2N (600 K) and CHCl2S(O)2N (700 K) dissociate completely in the gas phase, and in both cases, HCN, SO2, HCl, HNSO, and CO form. Additionally, ClCN, OCCl2, HNSO2, ?NSO2, and the atmospherically relevant radical ?CHCl2 are also identified among the fragmentation products of CHCl2S(O)2N. The underlying mechanisms for the rearrangement and decomposition of CH2ClS(O)2N and CHCl2S(O)2N are discussed based on the experimentally-observed products and the calculated potential energy profile.
关键词： decomposition,nitrenes,azides,reaction mechanism,photoisomerization,matrix isolation
更新于2025-09-19 17:15:36
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IR‐Laser Ablation of Potassium Cyanide: A Surprisingly Simple Route to Polynitrogen and Polycarbon Species
摘要： Pulsed laser irradiation of solid potassium cyanide (KCN) produces, besides free nitrogen and carbon atoms, the molecular species KN and KC which are potential candidates for interstellar species of potassium. Additionally, N3, N3?, and KC3 are produced and isolated in solid noble gases as well as in solid N2. Molecular potassium nitrene (KN) reacts with dinitrogen in neon and argon matrices after photochemical excitation (λ = 470 nm) forming molecular end-on (C∞v) and side-on (C2v) potassium azide isomers. The side-on isomer (C2v) is thermodynamically favored at the CCSD(T)/ma-def2-TZVP level of theory. It can be obtained from the end-on isomer by UV-irradiation (λ = 273 nm).
关键词： Laser Ablation,Quantum-Chemical Calculations,Polycarbon Compounds,Polynitrogen Compounds,Matrix-Isolation Spectroscopy
更新于2025-09-16 10:30:52
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Matrix isolation infrared spectroscopic study of the photochemistry of bis(cyclopentadienyl)dicarbonyl titanium in solid nitrogen
摘要： Infrared spectra of the photochemical products of bis(cyclopentadienyl)dicarbonyl titanium, TiCp2(CO)2, isolated in an Ar matrix and a N2 matrix were measured. UV-irradiation of TiCp2(CO)2 produced TiCp2(CO) in the Ar matrix, and three types of nitrogen-containing compounds, TiCp2(CO)(N2), TiCp2(N2), and TiCp2(N2)2 were produced in the N2 matrix. The yields of the species changed with the duration of UV-irradiation. Annealing of the sample resulted in the disappearance of unstable TiCp2(N2) and an increase of TiCp2(N2)2. Isotope shifts of the IR spectra were measured using 15N2 to confirm the assignments. The structures of the species were estimated using a double hybrid density functional theory calculation (mPW2PLYP/cc-pVTZ), and the calculated infrared frequencies were in very good agreement with the experimentally measured spectra.
关键词： Photochemistry,Infrared spectroscopy,Nitrogen activation,Titanium complexes,Matrix isolation
更新于2025-09-12 10:27:22
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Photoinduced reversible isomerization of 9H-fluorene into 1H-fluorene by means of hydrogen-atom migration and the lowest electronically excited triplet state studied by matrix-isolation FTIR spectroscopy
摘要： Photoinduced reversible intramolecular hydrogen-atom migration between 9H-?uorene and 1H-?uorene isolated in an Ar matrix is found by FTIR spectroscopy with an aid of DFT calculation. The forward isomerization from 9H-?uorene to 1H-?uorene occurs upon UV irradiation (λ ≥ 295 nm), while the backward isomerization occurs upon λ ≥ 320 nm light irradiation. The less stable isomer, 1H-?uorene, is identi?ed by comparison of the measured IR spectrum with the corresponding simulated spectral pattern obtained at the B3LYP/6-31++G(d,p) level. In addition, an IR spectrum of 9H-?uorene in the T1 state is measured during UV irradiation (λ ≥ 275 nm).
关键词： Electronically excited T1 state,Fluorene,Matrix-isolation infrared spectrum,Photoinduced hydrogen-atom migration
更新于2025-09-11 14:15:04
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First vibrational investigations of N <sub/>2</sub> O–H <sub/>2</sub> O, N <sub/>2</sub> O–(H <sub/>2</sub> O) <sub/>2</sub> , and (N <sub/>2</sub> O) <sub/>2</sub> –H <sub/>2</sub> O complexes from the far to the near-infrared spectral region by neon matrix isolation and <i>ab initio</i> calculations
摘要： We present for the first time the investigation of water molecules complexed with dinitrogen monoxide, two abundant molecules in atmosphere, in solid neon using Fourier transform infrared (IR) spectroscopy. We identify at least three complexes from concentration effects, N2O–H2O, N2O–(H2O)2, and (N2O)2–H2O, by observation of new absorption bands close to the monomer fundamental modes from the far to the near IR region. We highlight the presence of isomers for the N2O–H2O complex with the help of theoretical calculations at second order M?ller-Plesset (MP2) and coupled-cluster single double triple-F12a/aug-cc-pVTZ levels. The observed frequencies for the N2O–(H2O)2 and (N2O)2–H2O complexes are compared with MP2/aug-cc-pVTZ harmonic data. Anharmonic coupling constants have been derived from the observations of overtones and combination bands.
关键词： ab initio calculations,anharmonic coupling constants,neon matrix isolation,N2O–H2O complexes,Fourier transform infrared spectroscopy
更新于2025-09-09 09:28:46
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A SYMMETRICAL OUTPUTS UNIPLANAR OUT-OF-PHASE POWER DIVIDER WITHOUT PHASE SHIFTER
摘要： A new out-of-phase power divider (PD) without phase shifter at the output ports is proposed. Based on admittance matrix, a new topology of uniplanar power divider with symmetrical outputs is designed. Under conditions of good matching, perfect isolation, and 180? phase di?erence between two output ports, the corresponding design equations and synthesis procedures are derived and given with admittance matrix. To verify the design approach, an out-of-phase power divider operating at 2 GHz with equal power division ratio is designed, fabricated, and measured. Experimental results demonstrate that the input return loss is better than 32 dB, the insertion loss is less than 0.29 dB and the isolation is better than 33 dB. The amplitude imbalance between the output ports is 0.03 dB and the phase di?erence between the two output ports is 181.6? at the operation frequency. Further more, 49.9% relative bandwidth of 15 dB return loss and 39.4% relative bandwidth of 20 dB port isolation are achieved.
关键词： admittance matrix,isolation stubs,symmetrical outputs,uniplanar,out-of-phase power divider
更新于2025-09-04 15:30:14