Coordination of niobium and tantalum oxides by Ar, Xe and O2: Matrix isolation infrared spectroscopic and theoretical study of NbO2(Ng)2 (Ng = Ar, Xe) and MO4(X) (M = Nb, Ta; X = Ar, Xe, O2) in solid argon

The combination of matrix isolation infrared spectroscopic and quantum chemical calculation results indicate that the NbO₂ molecule is coordinated by two noble gas atoms in forming the NbO₂(Ng)₂ (Ng = Ar, Xe) complexes in solid noble gas matrixes. In contrast, the TaO₂ molecule is not able to form similar noble gas complex. The niobium and tantalum dioxides further react with dioxygen to form the side-on bonded superoxo-dioxide complexes MO₄ (M = Nb, Ta), which are coordinated by one argon atom in solid argon matrix. The coordinated Ar atom in MO₄(Ar) can be replaced by O₂ or Xe in forming the MO₆ and MO₄(Xe) complexes. The results indicate that the NbO₂, NbO₄ and TaO₄ molecules trapped in solid noble gas matrixes should be regarded as the NbO₂(Ng)₂ and MO₄(Ng) (Ng = Ar, Xe; M = Nb, Ta) complexes instead of “isolated” metal oxide species.     

Reactions of Group V Metal Atoms with Hydrogen Sulfide:Argon Matrix Infrared Spectra and Theoretical Calculations

The reaction of laser-ablated vanadium, niobium and tantalum atoms with hydrogen sulfide has been investigated using matrix isolation FTIR and theoretical calculations. The metal atoms inserted into the H-S bond of H₂S to form the HMSH molecules (M=V, Nb, Ta), which rearranged to H₂MS molecules on annealing for Nb and Ta. The HMSH molecule can also further react with another H₂S to form the H₂M(SH)₂ molecules. These new molecules were identified on the basis of the D₂S and H₂³⁴S isotopic substitutions. DFT (B3LYP and BPW91) theoretical calculations are used to predict energies, geometries, and vibrational frequencies for these novel metal dihydrido complexes and molecules. Reaction mechanism for formation of group V dihydrido complex was investigated by DFT internal reaction coordinate calculations. The dissociation of HVSH gave VS+H₂ on broad band irradiation and reverse reaction happened on annealing. Based on B3LYP calculation releasing hydrogen from HVSH is endothermic only by 13.5 kcal/mol with lower energy barrier of 16.9 kcal/mol.     

Matrix isolation infrared spectroscopic and theoretical study of noble gas coordinated dipalladium–dioxygen complexes

The reaction products of palladium atoms with molecular oxygen in solid argon have been investigated using matrix isolation infrared absorption spectroscopy and quantum chemical calculations. In addition to the previously reported mononuclear palladium–dioxygen complexes: Pd(η²–O₂) and Pd(η²–O₂)₂, dinuclear palladium–dioxygen complexes: Pd₂(η²–O₂) and Pd₂(η²–O₂)₂ were formed under visible light irradiation and were identified on the basis of isotopic substitution and theoretical calculations. In addition, experiments doped with xenon in argon coupled with theoretical calculations suggest that the Pd(η²–O₂), Pd₂(η²–O₂) and Pd₂(η²–O₂)₂ complexes are coordinated by two argon or xenon atoms in solid argon matrix, and therefore, should be regarded as the Pd(η²–O₂)(Ng)₂, Pd₂(η²–O₂)(Ng)₂ and Pd₂(η²–O₂)₂(Ng)₂ (NgAr or Xe) complexes isolated in solid argon.     

Cyclic M(SO2) (M=Zn,Cd) and its Anions: Matrix Infrared Spectra and DFT Calculations

Reaction of laser ablated zinc and cadmium atoms with SO₂ molecules was studied by low temperature matrix isolation infrared spectroscopy. Cyclic M(SO₂) and anion M(SO₂)^- (M=Zn, Cd) were produced in excess argon and neon, which were identified by ³⁴SO₂ and S¹⁸O₂ isotopic substitutions. The observed infrared spectra and molecular structures were confirmed by density functional theoretical calculations. Natural charge distributions indicated significant electron transfer from s orbitals of zinc or cadmium metal atom to SO₂ ligand and cyclic M(SO₂) complexes favored “ion pair” M⁺(SO₂)^- formation, which were trapped in low temperature matrices. In addition Zn-O or Cd-O bond in M(SO₂) exhibited strong polarized covalent character. Reaction of Hg atom with SO₂ was also investigated, but no reaction product was observed, due to the relativistic effect that resulted in the contraction of 6s valence shell and high ionization potential of Hg atom     

FTIR studies of the CH3CN–BF3 complex in solid Ar, N2, and Xe: Matrix effects on vibrational spectra

FTIR spectra of the four isotopically substituted 1:1 complexes of acetonitrile and boron trifluoride were recorded in Ar, N₂ and Xe matrices. In Ar, previously unreported three vibrational modes of the complex were clearly observed. Several significant vibrational bands were also observed in N₂ and Xe. The observed frequency shifts on complexation, Δν, were qualitatively in good agreement with the computational results, which were calculated at the B3LYP/6-311++G(d,p) level using the optimized geometry of the C_3v eclipsed conformation. The observed magnitudes of Δν for most of the complex bands were larger than the calculated values. The BF₃ symmetric deformation mode is an exception. The observed frequency shits for this mode were smaller than the calculated values, especially in N₂. This suggests that even an inert matrix can significantly affect the vibrational spectrum of the complex.     

Infrared matrix isolation study of the reaction of CrCl2O2 with (CH3)2O and (CH3)2CO

Matrix isolation has been combined with infrared spectroscopy to study the reaction chemistry of CrCl₂O₂ with (CH₃)₂O and (CH₃)₂CO. Very similar results were obtained with twin jet and room temperature merged jet deposition, indicating that the initial product forms on the surface of the matrix during deposition, not in the deposition lines prior to matrix condensation. The initial product in both systems was identified as the 1:1 complex between the two reagents, with a structure in which the oxygen atom of the base donates electron density to the Cr center. A number of perturbed vibrational modes of both subunits were observed; for the bases, these modes were vibrations involving the oxygen atom. Hg arc irradiation of the CrCl₂O₂·O(CH₃)₂ complex led to growth of a secondary product that is tentatively identified as Cl₂CrO(OCH₃)₂. The CrCl₂O₂·OC(CH₃)₂ complex was not photosensitive, and no rearrangements were observed.     

Matrix isolation study of the thermal and photochemical reaction of ozone with Trimethyl Indium

The matrix isolation technique has been combined with infrared spectroscopy and theoretical calculations to explore the reaction of (CH₃)₃In with O₃ over a range of time scales. Upon twin jet deposition (short reaction time), formation of the novel H₃COIn(CH₃)₂ species along with a low yield of CH₂O was observed. Subsequent UV irradiation greatly increased the yield of H₃COIn(CH₃)₂ while the intensities of the CH₂O bands were not affected. An extensive set of bands were seen for H₃COIn(CH₃)₂ after irradiation and ¹⁸O spectroscopic data was obtained as well. The identification of this species was supported by theoretical calculations at the B3LYP/lanl2dz and B3LYP/dgdzvp levels of theory. Merged jet deposition (longer reaction times) led to high yield of H₂CO, CH₃OH and C₂H₆, identifications that were confirmed by ¹⁸O substitution. Mechanistic inferences for the initial steps of this reaction are discussed.     

四（对—羟基）苯基卟啉配合物的傅里叶变换红外光声光谱

四（对-羟基）苯基卟啉（H2THPP）不仅能作为分析试剂，而且有一定的抗癌活性，还可作为合成卟啉类液晶材料的中间体．这种配体及其配合物由于颜色深、透光性能差和散射较强，用普通红外光谱法开展其振动光谱研究存在一定的困难．我们在用红外光声光谱（FTIR－PAS）技术[1]成功地研究了部分过渡金属、稀土金属叶琳配合物的基础上[2，3]，测试并研究了H2THPP及其Cr（III）、Mn（III）、Fe（III）、Co（II）、Ni（II）、Cu（II）、Zn（II）配合物在3700～200cm－1范围内的FTIR－PAS．对主要谱带进行了经验归属，讨论了配…     

2-[(2,4-二氯苯胺基)羰基]苯甲酸与过渡金属配合物的研究

本文报道了2-[2,4-二氯苯胺基)羰基]苯甲酸与5种过渡金属配合物的制备和表征,证实配合物是通过羧酸根上羟基氧原子和酰按羰基上氧原子配位成键,除Cu(Ⅱ)配合物分子为平面正方形结构外,其余均为八面体结构,只是扭曲程度不同。     

Matrix isolation infrared spectroscopic investigation of the coordination chemistry and reactivity of OVF3

The matrix isolation technique has been combined with infrared spectroscopy to identify and characterize the product of the codeposition of OVF₃ with NH₃ and with a series of nitrogen and oxygen donor bases into argon matrices at 14 K. This codeposition led to the formation of the isolated 1:1 complexes between OVF₃ and these bases. Each complex was characterized spectroscopically, including strong shifts to the V–F stretching modes, and a lesser shift to the V=O stretching mode. Numerous perturbed vibrational modes of the base subunits were noted, including a strong, 230 cm⁻¹ blue shift to the symmetric bending mode of NH₃. The magnitudes of these shifts indicate that OVF₃ is a moderate strength Lewis acid. However, in contrast to analogous reactions with OVCl₃, no further thermal or photochemical transformations of the complex occurred. Theoretical calculations were also carried out in support of the experimental work.     

生物柴油催化剂KF/Zn-Al固体碱的制备及表征

采用共沉淀、高温焙烧及KF掺杂Zn-Al类水滑石的方法制备了KF/Zn-Al固体碱催化剂。 通过正交试验考察了制备条件对KF/Zn-Al固体碱催化活性的影响,得到的优化条件为：陈化温度353 K、陈化时间16 h、焙烧温度823 K、焙烧时间6 h及m(KF)/m(Zn-Al)=1。 以优化条件下制备的KF/Zn-Al固体碱为催化剂,在n(醇)/n(油)=9、m(催化剂)/m(油)=0.04、反应温度338 K、反应时间0.5 h的条件下,菜籽油转化率可达97.75%。 采用TG DTG、BET、XRD、SEM技术及Hammett指示剂法对催化剂及其前驱体进行了表征。 对催化剂结构及表面性质与其活性之间的关系进行了讨论。     

Matrix isolation and theoretical study of the photochemical reaction of CH3CN with CrO2Cl2 and OVCl3

The matrix isolation technique has been combined with theoretical calculations to identify and characterize the photoproducts in the reactions of CH₃CN with CrCl₂O₂ and OVCl₃. Twin jet co-deposition of these reagents led to the formation of a 1:1 molecular complex which was observed using UV/visible spectroscopy. Irradiation of these matrices with light of λ>300 nm led to the observation of new bands in the infrared spectra, the most intense of which was seen at 1942 cm⁻¹ for the CrCl₂O₂/CH₃CN system. The product bands are assigned to the ²η complexes of acetonitrile n-oxide with CrCl₂O and VCl₃, respectively. Identification of these species was supported by extensive isotopic labeling (²H and ¹⁵N), as well as by B3LYP/6-311++G(d,2p) density functional calculations.     

Matrix isolation study of the reaction of dimethyl sulfoxide with CrCl2O2 and OVCl3

The matrix isolation technique, combined with infrared spectroscopy and theoretical calculations, has been employed to investigate the thermal and photochemical reactions of dimethylsulfoxide (DMSO) with CrCl₂O₂ and OVCl₃. Twin jet codeposition leads to formation and isolation of a photochemically unstable 1:1 complex. The photoproduct in the twin jet DMSO + CrCl₂O₂ experiments is identified as dimethyl sulfone, (CH₃)₂SO₂, interacting with the Cl₂CrO fragment, while in the analogous OVCl₃ reaction, the photoproduct bands were too weak to allow product identification. Merged jet codeposition led to rapid gas phase reaction, and in the case of DMSO + CrCl₂O₂, dimethyl sulfone is formed in high yield. This marks the first demonstration of a gas phase thermal oxygen atom transfer from CrCl₂O₂ to an organic substrate. For the reaction of DMSO with OVCl₃, no volatile products are deposited in the matrix and dimethyl sulfone is not a product. These results support differing pathways for the reactions of CrCl₂O₂ and OVCl₃, a conclusion that is supported by density functional calculations.     

固体表面金属有机化合物的结构及其性质

表面金属有机化学是近年来一个快速发展的新研究领域。通过这种思想和方法所合成出的表面金属有机化合物具有明确的结构和特殊的性质,在催化研究和材料制备中有着广泛的应用,国内外已经进行了大量的研究并取得了许多非常有价值的结果。本文引用了40余篇文献侧重评述了氧化物、金属、沸石等固体表面金属有机化合物的结构和性质。     

复合物Mg＋-NCSCH3, Ca＋-NCSCH3光解离光谱研究

研究了复合物Mg^＋-NCSCH₃在230～440 nm波段和Ca^＋-NCSCH₃在320～560 nm波段的光解离光谱. 复合物Mg^＋-NCSCH₃, Ca^＋-NCSCH₃光诱导反应的产物质谱表明有非反应猝灭产物Mg^＋(Ca^＋), C—S键断裂产物Mg^＋(Ca^＋)NC 和Mg^＋(Ca^＋)NCS以及重排反应产物Mg^＋(Ca^＋)-CHSH通道. 在原子跃迁谱线(3²S→3²P, 对于Mg^＋; 4²S?4²P, 对于Ca^＋)的红和蓝两边, Mg^＋-NCSCH₃的光解离光谱由两个宽峰组成; 而对于Ca^＋-NCSCH₃, 则是由三个谱峰构成. CIS/6-311＋＋G^**等级上, 对应于基态构型的Mg^＋-NCSCH₃电子态跃迁能量和振子强度与实验光谱较为一致; 而Ca^＋-NCSCH₃有较大的差别. 这是因为CIS方法忽略电子相关效应, 而Ca^＋-based的跃迁中3d和4s轨道间存在较强的混合所致.     

Matrix isolation infrared studies of complexes formed between substituted phenols and trimethylamine

Infrared spectroscopy and matrix isolation technique have been used to study the 1 : 1 complexes formed between 2,4,5-trichlorophenol (TCP), pentachlorophenol (PCP) or 2-chloro-4,6-dinitrophenol (CNP) and trimethylamine (TMA) isolated in solid argon. The results were analyzed in relation to the type of complex formed. Depending on the proton-donor ability of the phenol three different types of hydrogen bonded complexes have been identified in argon matrices. The weakest phenol in the series, TCP (pK_a = 6.72), forms a strong molecular hydrogen bonded complex with TMA as indicated by the broad ν(OHN) absorption with a maximum at 2490 cm⁻¹ and a band at 811 cm⁻¹ due to the ν_s(C₃N) mode of the perturbed amine. The strongest phenol, CNP (pK_a = 2.01), interacts with TMA in an argon matrix to form ionic complex with the proton transferred to the base molecule. This is evidenced by the presence of the ν(NH⁺---O⁻) absorption between 3000−1800 cm⁻¹, by the ν_as(C₃N⁺) and ν_s(C₃N⁺) absorptions due to the protonated amine and by numerous product bands due to the relatively strongly perturbed modes of the phenol ring. The interaction between TMA and a phenol of intermediate strength, PCP (pK_a = 4.74), in solid argon probably leads to the formation of two types of hydrogen bonded complexes: an ionic complex with the proton transferred to the amine molecule and a pseudosymmetric one with the proton more or less equally shared between the phenol and amine molecules. In this case the protonic absorption consists of two broad features situated in the 3000–1600 cm⁻¹ and 950–400 cm⁻¹ regions due to the ν(NH⁺O⁻) and ν(OHN) modes, respectively.     

Formation and Photodissociation of Transition Metal-Sulfur Binary Cluster Ions

Transition metal-sulfur binary cluster ions were produced by direct laser ablation and analyzed with the first stage time-of-flight mass spectrometer (TOF-MS). It was found that the distribution of the strong peaks of the stable cluster ions in the TOF-MS were not appreciably affected by the composition of the sample. The composition of the most stable metal-sulfur cluster ions, M_nS_m are different for various transition metals: Cu, n = 2m + I and n = 2m; Zn, m = n; Mn, m = n; Fe, m = n, m = n ?1 and m = n ? 2; Co, m = n ? 1, m = n ? 2, m = n ? 3, m = n ? 4 and m = n ? 5; Cr, m = n and m = n + 1; Ta, m = n + 1 and m = n + 2. Cluster ions can be selected by a mass gate, and photolyzed by an excimer laser. The photodissociation product ions were analyzed with the second stage TOF-MS. These product ions were mainly the more stable cluster ions as those given in the first stage TOF-MS.     

An ab initio and matrix isolation infrared study of the 1:1 C2H2–CHCl3 adduct

The details of weak C–Hπ interactions that control several inter and intramolecular structures have been studied experimentally and theoretically for the 1:1 C₂H₂–CHCl₃ adduct. The adduct was generated by depositing acetylene and chloroform in an argon matrix and a 1:1 complex of these species was identified using infrared spectroscopy. Formation of the adduct was evidenced by shifts in the vibrational frequencies compared to C₂H₂ and CHCl₃ species. The molecular structure, vibrational frequencies and stabilization energies of the complex were predicted at the MP2/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels. Both the computational and experimental data indicate that the C₂H₂–CHCl₃ complex has a weak hydrogen bond involving a C–Hπ interaction, where the C₂H₂ acts as a proton acceptor and the CHCl₃ as the proton donor. In addition, there also appears to be a secondary interaction between one of the chlorine atoms of CHCl₃ and a hydrogen in C₂H₂. The combination of the C–Hπ interaction and the secondary ClH interaction determines the structure and the energetics of the C₂H₂–CHCl₃ complex. In addition to the vibrational assignments for the C₂H₂–CHCl₃ complex we have also observed and assigned features owing to the proton accepting C₂H₂ submolecule in the acetylene dimer.     

超氧化物歧化酶模型化合物的合成、表征及其SOD活性研究

合成了 4种过渡金属硝酸盐与三 (2 苯并咪唑亚甲基 )胺 (ntb)和水杨酸 (Hsal)的新固体配合物 ,经元素分析确定其组成分别为 [M2 (ntb) 2 (Hsal) 2 ](NO3 ) 2 ·H2 O(M =Zn ,Co)、[M2 (ntb) 2 (Hsal) ](NO3 ) 3 ·3H2 O(M =Cu)和 [M(ntb) (Hsal) ](NO3 )·2H2 O(M =Ni) ,进行了摩尔电导率、热重、红外与紫外可见光谱、1HNMR等性质的表征。研究了配合物的模拟SOD活性 ,用IC50 表征配合物的模拟SOD活性的大小。