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1.
Synthesis, Vibrational Spectra, and Crystal Structure of ( n ‐Bu4N)2[(W6Cl )F ] · 2 CH2Cl2 and 19F NMR Spectroscopic Evidence of the Mixed Cluster Anions [(W6Cl )F Cl ]2–, n = 1–6 The reaction of (n‐Bu4N)2[(W6Cl)Cl] with CF3COOH in dichloromethane gives intermediately a mixture of the cluster anions [(W6Cl)(CF3COO)Cl]2–, n = 1–6. By treatment with NH4F the outer sphere coordinated trifluoracetato ligands are easily substituted and the components of the series [(W6Cl)FCl], n = 1–6 are formed and characterized by their distinct 19F NMR chemical shifts. An X‐ray structure determination has been performed on a single crystal of (n‐Bu4N)2[(W6Cl)F] · 2 CH2Cl2 (orthorhombic, space group Pbca, a = 15.628(4), b = 17.656(3), c = 20.687(4) Å, Z = 4). The low temperatur IR (60 K) and Raman (20 K) spectra are assigned by normal coordinate analysis based on the molecular parameters of the X‐ray determination. The valence force constants are fd(WW) = 1.89, fd(WF) = 2.43 and fd(WCl) = 0.93 mdyn/Å.  相似文献   

2.
Thin films of AgSbS2 are important for phase‐change memory applications. This solid is deposited by various techniques, such as metal organic chemical vapour deposition or laser ablation deposition, and the structure of AgSbS2(s), as either amorphous or crystalline, is already well characterized. The pulsed laser ablation deposition (PLD) of solid AgSbS2 is also used as a manufacturing process. However, the processes in plasma have not been well studied. We have studied the laser ablation of synthesized AgSbS2(s) using a nitrogen laser of 337 nm and the clusters formed in the laser plume were identified. The ablation leads to the formation of various single charged ternary AgpSbqSr clusters. Negatively charged AgSbS, AgSb2S, AgSb2S, AgSb2S and positively charged ternary AgSbS+, AgSb2S+, AgSb2S, AgSb2S clusters were identified. The formation of several singly charged Ag+, Ag, Ag, Sb, Sb, S ions and binary AgpSr clusters such as AgSb, Ag3S?, SbS (r = 1–5), Sb2S?, Sb2S, Sb3S (r = 1–4) and AgS, SbS+, SbS, Sb2S+, Sb2S, Sb3S (r = 1–4), AgSb was also observed. The stoichiometry of the clusters was determined via isotopic envelope analysis and computer modeling. The relation of the composition of the clusters to the crystal structure of AgSbS2 is discussed. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

3.
Reactions of dry THF/MeCN solutions of Ca[Re6SCl(Cla)6] with silylated derivatives E(SiMe3)2 (E = PhAs, PSiMe3, HN, O, S) and addition of trialkylphosphine PPr3 afford in high yields and at room temperature either the neutral clusters [Re6SX(PPr3)] ( 1 : X = As, 2 : X = P) or the ionic compounds [Re6SX(PPr3)]2+ · [Re6S6Cl8]2– ( 3 : X = NH, 4 : X = O, 5 : X = S). The compounds 1 – 5 were characterised by X‐ray crystal structure analysis. A di‐substitution reaction occurs on the {Re6SCl}4+ cluster core, where the two inner μ3‐chloro ligands Cli are substituted by X (X = As, P, NH, O, S) and all six terminal chloro ligands Cla are exchanged by terminal PPr3‐ligands.  相似文献   

4.
An algorithm for evaluation of two‐center, three‐electron integrals with the correlation factors of the type rr and rrr as well as four‐electron integrals with the correlation factors rrr and rrr in the Slater basis is presented. This problem has been solved here in elliptical coordinates, using the generalized and modified form of the Neumann expansion of the interelectronic distance function r for k ≥ ?1. Some numerical results are also included. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004  相似文献   

5.
A systematic density functional theory and wave function theory investigation on the geometrical and electronic structures of the electron‐deficient diboron aurides B2Au (n = 1, 3, 5) and their mixed analogues B2HmAu (m + n = 3, 5) has been performed in this work. Ab initio theoretical evidences strongly suggest that bridging gold atoms exist in the ground states of C2v B2Au?(1A1), C2 B2Au(1A), C2v B2Au3(2B1), C2v B2Au(1A1), and Cs B2Au5(2A″), which all prove to possess a B? Au? B three‐center‐two‐electron (3c‐2e) bond. For B2HmAu (m + n = 3, 5) mixed anions, bridging B? Au? B units appear to be favored in energy over bridging B? H? B, as demonstrated by the fact that the Au‐bridged C2v B2H2Au? (1A1), Cs B2HAu (1A′), and C1 B2HAu (1A) lie clearly lower than their H‐bridged counterparts Cs B2H2Au? (1A′), C2 B2HAu (1A), and C2v B2HAu (1A1), respectively. Orbital analyses indicate that Au 6s makes about 92–96% contribution to the Au‐based orbitals in these B‐Au‐B 3c‐2e interactions, whereas Au 5d contributes 8–4%. The adiabatic and vertical detachment energies of the concerned anions have been calculated to facilitate their future experimental characterizations. The results obtained in this work establish an interesting 3c‐2e bonding model (B? Au? B) for electron‐deficient systems in which Au 6s plays a major role with non‐negligible contribution from Au 5d. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011  相似文献   

6.
The results of calculating the average polarizabilities, first and second hyperpolarizabilities and molar Kerr constants of C5H, C6H, 2-C10H, 2-C14H, C8H and C8H are reported. The main elements of our computational scheme are McWeeny's coupled Hartree–Fock perturbation theory and an extended basis CNDO wave function. It is shown that the studied anions have nonlinearities within the same order of magnitude as their respective uncharged parent molecules. The Kerr constants of these anions are analyzed and the contribution of the various terms is appraised.  相似文献   

7.
On Ordered Perovskites with Cationic Vacancies. XI. Compounds of Type A B B □1/4WVIO6 ? A BIIB □W O24 with AII, BII = Ba, Sr Depending on the ionic radii of the two and three valent cations in the perovskites of type ABB □1/4WVIO6 ?; ABIIB □WO24 order disorder phenomena are present. The results of the x-ray and vibrational spectroscopic investigations as well as the diffuse reflectance spectra and the visible photoluminescence are reported.  相似文献   

8.
A simplified analysis is presented for the evaluation of the three‐electron one‐center integrals of the form ∫rrrrrred r 1d r 2d r 3, for the cases i, j, k, ≥−2, l=−2, m≥−1, n≥−1. These integrals arise in the calculation of lower bounds for energy levels and certain relativistic corrections to the energy when Hylleraas‐type basis sets are employed. Convergence accelerator techniques are employed to obtain a reasonable number of digits of precision, without excessive CPU requirements. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 93–99, 1999  相似文献   

9.
A density functional theory investigation on the geometrical and electronic properties of B4S (B2(BS)) and B5S (B(BS)) clusters has been performed in this work. Both the doublet B2(BS) ([S?B? BB? B?S]?) (D∞h, 2Πu) and the singlet B2(BS) ([S?B? B?B? B?S]2?) (D∞h, 1Σ) proved to have perfect linear ground‐state structures containing a multiply bonded BB core (BB or B?B) terminated with two BS groups, while Td B(BS) turned out to possess a perfect B? tetrahedral center directly corrected to four BS groups, similar to the corresponding boron hydride molecules of D∞h B2H, D∞h B2H, and Td BH, respectively. B4S2 and B5S4 neutrals, however, appeared to be much different: they favor a planar fan‐shaped C2v B4S2 (a di‐S‐bridged B4 rhombus) and a planar kite‐like C2v B5S4 (a di‐S‐bridged B3 triangle bonded to two BS groups), respectively. One‐electron detachment energies and symmetrical stretching vibrational frequencies are calculated for D∞h B2(BS) and Td B(BS) monoanions to facilitate their future characterizations. Neutral salts of B2(BS)2Li2 with an elusive B?B triple bond and B(BS)4Li containing a tetrahedral B? center are predicted possible to be targeted in experiments. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010  相似文献   

10.
Synthesis, Crystal Structures, and Vibrational Spectra of [(Ph3P)2N]2[(W6Cl )I ] · 2 Et2O · 2 CH2Cl2 and [(Ph3P)2N]2[(W6Cl )(NCS) ] · 2 CH2Cl2 By treatment of [(W6Cl)I]2– with (SCN)2 in dichloromethane at –20 °C the hexaisothiocyanato cluster anion [(W6Cl)(NCS)]2– is formed. X‐ray structure determinations have been performed on single crystals of [(Ph3P)2N]2[(W6Cl)I] · 2 CH2Cl2 · 2 Et2O ( 1 ) (triclinic, space group P1, a = 10.324(5), b = 14.908(3), c = 17.734(8) Å, α = 112.78(2)°, β = 99.13(3)°, γ = 92.02(3)°, Z = 1) and [(Ph3P)2N]2[(W6Cl)(NCS)] · 2 CH2Cl2 ( 2 ) (triclinic, space group P1, a = 11.115(2), b = 14.839(2), c = 17.036(3) Å, α = 104.46(1)°, β = 105.75(2)°, γ = 110.59(1)°, Z = 1). The thiocyanate ligands of 2 are bound exclusively via N atoms with W–N bond lengths of 2.091–2.107 Å, W–N–C angles of 173.1–176.9° and N–C–S angles of 178.1–179.3°. The vibrational spectra exhibit characteristic innerligand vibrations at 2067–2045 (νCN), 879–867 (νCS) and 490–482 (δNCS). Based on the molekular parameters of the X‐ray determination of 1 the vibrational spectra of the corresponding (n‐Bu4N) salt of 1 are assigned by normal coordinate analysis. The valence force constants are fd(WW) = 1.61, fd(WI) = 1.23 and fd(WCl) = 1.10 mdyn/Å.  相似文献   

11.
Protonated benzene, C6H, has been studied extensively to understand the structure and energy of a protonated organic molecule in the gas phase. The formation of C6H is either through direct protonation of benzene, i.e., chemical ionization, or through fragmentation of certain radical cations produced from electron ionization or photon ionization. We report a novel observation of C6H as a product ion formed in the collision‐induced dissociation (CID) of protonated benzamide and related molecules produced via electrospray ionization (ESI). The formation of C6H from these even‐electron precursor ions during the CID process, which has not been previously reported, is proposed to occur from the protonated molecules via a proton migration in a five‐membered ring intermediate followed by the cleavage of the mono‐substituent C? C bond and concurrent formation of an ion‐molecule complex. This unique mechanism has been scrutinized by examining some deuterated molecules and a series of structurally related model compounds. This finding provides a convenient mean to generate C6H, a reactive intermediate of considerable interest, for further physical or chemical investigation. Further studies indicate that the occurrence of C6H in liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) appears to be a rather common phenomenon for many compounds that contain ‘benzoyl‐type’ moieties. Hence, the observation of the C6H ion in LC/ESI‐MS/MS can be used as an informative fragmentation pathway which should facilitate the identification of a great number of compounds containing the ‘benzoyl‐type’ and similar structural features. These compounds are frequently present in food and pharmaceutical products as leachable impurities that require strict control and rapid elucidation of their identities. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

12.
Vibration spectra and force constants of the series O2PF — S2PF — S2P(CH3). The vibrational spectra of OSPF, S2PF, S2PF(CH3) and S2P(CN) are reported and discussed with O2PF and S2P(CH3). On the basis of a simplified valence-force-field the force constants are calculated and the bonding relations are discussed. In the ions, f PF is lower than in corresponding molecules. The ionic charge is distributed over nearly all atoms of the ions.  相似文献   

13.
(S)‐1‐Cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐ 4‐carboxylate [ (S)‐11 ] and (R)‐1‐cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐4‐carboxylate [( R)‐11 ] enantiomers, both greater than 99% enantiomeric excess, and their corresponding homopolymers, poly[ (S)‐11 ] and poly[ (R)‐11 ], with well‐defined molecular weights and narrow molecular weight distributions were synthesized and characterized. The mesomorphic behaviors of (S)‐11 and poly[ (S)‐11 ] are identical to those of (R)‐11 and poly[ (R)‐11 ], respectively. Both (S)‐11 and (R)‐11 exhibit enantiotropic SA, S, and SX (unidentified smectic) phases. The corresponding homopolymers exhibit SA and S phases. The homopolymers with a degree of polymerization (DP) less than 6 also show a crystalline phase, whereas those with a DP greater than 10 exhibit a second SX phase. Phase diagrams were investigated for four different pairs of enantiomers, (S)‐11 /( R)‐11 , (S)‐11 /poly[ (R)‐11 ], and poly[ (S)‐11 ]/poly[ (R)‐11 ], with similar and dissimilar molecular weights. In all cases, the structural units derived from the enantiomeric components are miscible and, therefore, isomorphic in the SA and S phases over the entire range of enantiomeric composition. Chiral molecular recognition was observed in the SA and SX phases of the monomers but not in the SA phase of the polymers. In addition, a very unusual chiral molecular recognition effect was detected in the S phase of the monomers below their crystallization temperature and in the S phase of the polymers below their glass‐transition temperature. In the S phase of the monomers above the melting temperature and of the polymers above the glass‐transition temperature, nonideal solution behavior was observed. However, in the SA phase the monomer–polymer and polymer–polymer mixtures behave as an ideal solution. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3631–3655, 2000  相似文献   

14.
Ab initio calculations are performed with 6–31G basis set to study the geometry and binding of the H3O, H5O, H7O, and H9O complexes. The H3O complex is also investigated with the 6–31 G* basis set and MP 2 (Moller–Plesset perturbation theory of second order).  相似文献   

15.
Non‐transition metal‐catalyzed living radical polymerization (LRP) of vinyl chloride (VC) in water at 25–35 °C is reported. This polymerization is initiated with iodoform and catalyzed by Na2S2O4. In water, S2O dissociates into SO that mediates the initiation and reactivation steps via a single electron transfer (SET) mechanism. The exchange between dormant and active propagating species also includes the degenerative chain transfer to dormant species (DT). In addition, the SO2 released from SO during the SET process can add reversibly to poly(vinyl chloride) (PVC) radicals and provide additional transient dormant ~SO radicals. This novel LRP proceeds mostly by a combination of competitive SET and DT mechanisms and, therefore, it is called SET‐DTLRP. Telechelic PVC with a number‐average molecular weight (Mn) = 2,000–55,000, containing two active ~CH2? CHClI chain ends and a higher syndiotacticity than the commercial PVC were obtained by SET‐DTLRP. This PVC is free of structural defects and exhibits a higher thermal stability than commercial PVC. SET‐DTLRP of VC is carried out under reaction conditions related to those used for its commercial free‐radical polymerization. Consequently, SET‐DTLRP is of technological interest both as an alternative commercial method for the production of PVC with superior properties as well as for the synthesis of new PVC‐based architectures. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6267–6282, 2004  相似文献   

16.
Summary: A highly selective protein assay was created which combines the fluorescent ratiometric technique based on FRET with the light‐harvesting properties of conjugated polymers. The cationic poly[(9,9‐bis(6′‐N,N,N‐trimethylammonium)‐hexyl)‐fluorene phenylene] bromide (PFP‐NMe) and the negatively charged biotinylated fluorescein probe (Fl‐B) were used to detect the target protein streptavidin optically. The strong electrostatic interactions between PFP‐NMe and fluorescein result in efficient FRET from PFP‐NMe to fluorescein. In the presence of streptavidin, however, the biotin moiety of Fl‐B specifically associates with streptavidin and the fluorescein molecule is buried deeply in the adjacent vacant binding sites. This separates the fluorescein spatially from the PFP‐NMe moiety, resulting in inefficient FRET from PFP‐NMe to fluorescein. Although a nonspecific protein, such as BSA, shows nonspecific interactions with PFP‐NMe, it does not affect the fluorescent ratio value of PFP‐NMe to fluorescein. Hence, the charged neutral complex of two oppositely charged conjugated polymers can eliminate the nonspecific interactions, and thus optimize their application in protein assays.

A schematic representation of the protein assay operation.  相似文献   


17.
19F NMR Spectroscopic Evidence and Calculation of the Statistical Formation of Mixed Cluster Anions [(Mo6I Cl )F ]2?, n = 0–7, and Preparation of (TBA)2[(Mo6I )F ] The octa-μ3-iodo-hexafluoro-hexamolybdate(2?)ion [(Mo6I)F]2? is prepared for the first time. The system of the 21 innersphere mixed clusters (Mo6ICl)4+, n = 0–7 is formed by exchange of innersphere bound Cli against outersphere bound Ia on tempering solid [(Mo6Cl)I] at 400°C. Prolonged tempering leads to increasing average n values of the mixture, which is converted into the tetrabutylammonium salt (TBA)2[(Mo6ICl)F]. Using increments of chemical shifts and integral peak intensities the 54 19F-nmr signals of the 21 species (compound n = 8 is absent) are assigned and confirmed by the 2 D-19F/19F-COSY spectrum. From the measured intensities the distribution of the different compounds is determined and proves significant deviation from statistical occupation, revealing the preference of isomers with iodine atoms occupying edges of the innersphere cube and discrimination of those sharing diagonals of the faces. Moreover all compounds with n = 3 and 4 are present overaverage in comparison to the others.  相似文献   

18.
Termination kinetics of methyl methacrylate (MMA) bulk polymerization has been studied via the single pulsed laser polymerization–electron paramagnetic resonance method. MMA‐d8 has been investigated to enhance the signal‐to‐noise quality of microsecond time‐resolved measurement of radical concentration. Chain‐length‐dependent termination rate coefficients of radicals of identical size, k, are reported for 5–70 °C and up to i = 100. k decreases according to the power‐law expression . At 5 °C, kt for two MMA radicals of chain‐length unity is k = (5.8 ± 1.3) · 108 L · mol−1 · s−1. The associated activation energy and power‐law exponent are: EA(k) ≈ 9 ± 2 kJ · mol−1 and α ≈ 0.63 ± 0.15, respectively.

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19.
The substituted thiourea, 4‐methyl‐3‐thiosemicarbazide, was oxidized by iodate in acidic medium. In high acid concentrations and in stoichiometric excess of iodate, the reaction displays an induction period followed by the formation of aqueous iodine. In stoichiometric excess of methylthiosemicarbazide and high acid concentration, the reaction shows a transient formation of aqueous iodine. The stoichiometry of the reaction is: 4IO + 3CH3NHC(S)NHNH2 + 3H2O → 4I + 3SO + 3CH3NHC(O)NHNH2 + 6H+ (A). Iodine formation is due to the Dushman reaction that produces iodine from iodide formed from the reduction of iodate: IO + 5I + 6H+ → 3I2(aq) + 3H2O (B). Transient iodine formation is due to the efficient acid catalysis of the Dushman reaction. The iodine produced in process B is consumed by the methylthiosemicarbazide substrate. The direct reaction of iodine and methylthiosemicarbazide was also studied. It has a stoichiometry of 4I2(aq) + CH3NHC(S)NHNH2 + 5H2O → 8I + SO + CH3NHC(O)NHNH2 + 10H+ (C). The reaction exhibits autoinhibition by iodide and acid. Inhibition by I is due to the formation of the triiodide species, I, and inhibition by acid is due to the protonation of the sulfur center that deactivates it to further electrophilic attack. In excess iodate conditions, the stoichiometry of the reaction is 8IO + 5CH3NHC(S)NHNH2 + H2O → 4I2 + 5SO + 5CH3NHC(O)NHNH2 + 2H+ (D) that is a linear combination of processes A and B. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 193–203, 2000  相似文献   

20.
Treatment of an acetonitrile solution of CuI with 1, 10‐dithia‐18‐crown‐6 (1, 10DT18C6) in the presence of Rb2CO3 leads to formation of the lamellar coordination polymer [Rb{Cu4I5(1, 10DT18C6)2}] ( 1 ).The anionic network of 1 is composed of parallel [(Cu4I5)] chains linked by bridging thiacrown ether ligands, pairs of which coordinate the Rb+ counter cations. [Cs{Cu5I6(1, 10DT18C6)2}] ( 2 ) can be prepared under similar conditions but contains separated helical anionic chains. In this case 1, 10DT18C6 ligands bridge copper atoms of individual chains in an intrastrand manner. In contrast the coordination networks in [(CuCN)2(1, 10DT18C6)] ( 3 ) and [K2{Cu12(CN)14(1, 10DT18C6)3} · CH3CN] ( 4 ) are both three‐dimensional and based on CuCN‐containing sheets bridged by 1, 10DT18C6 ligands. In the latter compound pairs of K+ cations are coordinated by groups of three thiacrown ether molecules. The neutral network of 3 can imbibe up to 31 % KNO3 per 1, 10DT18C6 pair without loss of lattice integrity.  相似文献   

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