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1.
Tsuzuki S Wakisaka A Ono T Sonoda T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(3):951-960
The geometries and interaction energies of complexes of pyridine with C6F5X, C6H5X (X=I, Br, Cl, F and H) and RFI (RF=CF3, C2F5 and C3F7) have been studied by ab initio molecular orbital calculations. The CCSD(T) interaction energies (Eint) for the C6F5X–pyridine (X=I, Br, Cl, F and H) complexes at the basis set limit were estimated to be ?5.59, ?4.06, ?2.78, ?0.19 and ?4.37 kcal mol?1, respectively, whereas the Eint values for the C6H5X–pyridine (X=I, Br, Cl and H) complexes were estimated to be ?3.27, ?2.17, ?1.23 and ?1.78 kcal mol?1, respectively. Electrostatic interactions are the cause of the halogen dependence of the interaction energies and the enhancement of the attraction by the fluorine atoms in C6F5X. The values of Eint estimated for the RFI–pyridine (RF=CF3, C2F5 and C3F7) complexes (?5.14, ?5.38 and ?5.44 kcal mol?1, respectively) are close to that for the C6F5I–pyridine complex. Electrostatic interactions are the major source of the attraction in the strong halogen bond although induction and dispersion interactions also contribute to the attraction. Short‐range (charge‐transfer) interactions do not contribute significantly to the attraction. The magnitude of the directionality of the halogen bond correlates with the magnitude of the attraction. Electrostatic interactions are mainly responsible for the directionality of the halogen bond. The directionality of halogen bonds involving iodine and bromine is high, whereas that of chlorine is low and that of fluorine is negligible. The directionality of the halogen bonds in the C6F5I– and C2F5I–pyridine complexes is higher than that in the hydrogen bonds in the water dimer and water–formaldehyde complex. The calculations suggest that the C? I and C? Br halogen bonds play an important role in controlling the structures of molecular assemblies, that the C? Cl bonds play a less important role and that C? F bonds have a negligible impact. 相似文献
2.
Yan Xiong Shuting Zhang Xuege Ling Xu Zhang Jinyue Wang 《International journal of quantum chemistry》2012,112(12):2475-2481
CCSD(T) calculations have been used for identically nucleophilic substitution reactions on N‐haloammonium cation, X? + NH3X+ (X = F, Cl, Br, and I), with comparison of classic anionic SN2 reactions, X? + CH3X. The described SN2 reactions are characterized to a double curve potential, and separated charged reactants proceed to form transition state through a stronger complexation and a charge neutralization process. For title reactions X? + NH3X+, charge distributions, geometries, energy barriers, and their correlations have been investigated. Central barriers ΔE for X? + NH3X+ are found to be lower and lie within a relatively narrow range, decreasing in the following order: Cl (21.1 kJ/mol) > F (19.7 kJ/mol) > Br (10.9 kJ/mol) > I (9.1 kJ/mol). The overall barriers ΔE relative to the reactants are negative for all halogens: ?626.0 kJ/mol (F), ?494.1 kJ/mol (Cl), ?484.9 kJ/mol (Br), and ?458.5 kJ/mol (I). Stability energies of the ion–ion complexes ΔEcomp decrease in the order F (645.6 kJ/mol) > Cl (515.2 kJ/mol) > Br (495.8 kJ/mol) > I (467.6 kJ/mol), and are found to correlate well with halogen Mulliken electronegativities (R2 = 0.972) and proton affinity of halogen anions X? (R2 = 0.996). Based on polarizable continuum model, solvent effects have investigated, which indicates solvents, especially polar and protic solvents lower the complexation energy dramatically, due to dually solvated reactant ions, and even character of double well potential in reactions X? + CH3X has disappeared. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
3.
Preparation and Spectroscopic Characterization of the Fluorophosphonium Salts X2FPSCH3+MF6? (X = Br, Cl; M = As, Sb) and XF2PSCH3+SbF6? (X = Br, Cl, F) The preparation of the fluorophosphonium salts X2FPSCH3+MF6? (X = Br, Cl; M = As, Sb) and XF2PSCH3+SbF6? (X = Br, Cl, F) by methylation of the corresponding thiophosphorylhalides in the system CH3F/SO2/MF5 (M = As, Sb) is reported. The new salts are characterized by their vibrational and NMR spectra. 相似文献
4.
The optimal geometry of isomeric molecules of (XP-CCl2)2 with X = F, Cl, Br was determined by RHF/6-31G(d) calculations. With X = F and Cl, the electronic correlation was considered on the MP2/6-31G(d) level. The P2C2 ring is nonplanar. With X = Cl and Br, the trans conformation is energetically preferable compared to the two possible cis conformations: by 7.8 and 14.2 kJ mol-
1 for X = Cl and by 7.5 and 14.1 kJ mol-
1 with X = Br. respectively. With X = F, the calculated energies of the cis and trans forms are very close. 相似文献
5.
Gas‐phase anionic reactions X? + CH3SY (X, Y = F, Cl, Br, I) have been investigated at the level of B3LYP/6‐311+G (2df,p). Results show that the potential energy surface (PES) of gas‐phase reactions X? + CH3SY (X, Y = Cl, Br, I) has a quadruple‐well structure, indicating an addition–elimination (A–E) pathway. The fluorine behaves differently in many respects from the other halogens and the reactions F? + CH3SY (Y = F, Cl, Br, I) correspond to deprotonation instead of substitution. The gas‐phase reactions X? + CH3SF (X = Cl, Br, I), however, follow an A–E pathway other than the last two out going steps (COM2 and PR) that proceeds via a deprotonation. The polarizable continuum model (PCM) has been used to evaluate the solvent effects on the energetics of the reactions X? + CH3SY (X, Y = Cl, Br, I). The PES is predicted to be unimodal in the solvents of high polarity. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
6.
Preparation of N-Methylhalidonitrilium Salts XCNCH3+MF6? (X = Cl, Br, I; M = As, Sb) and the N-Methyl-trifluoroacetonitrilium Salts CF3CNCH3+MF6? The N-methyl-halidonitrilium salts XCNCH3+MF6? (X = Cl, Br, I; M = As, Sb) are synthesized by methylation of cyanogen halides with CH3F/MF5 in SO2 at low temperatures. The N-methyl-trifluoroacetonitrilium salts CF3CNCH3+MF6? (M = As, Sb) are formed analogous with trifluoroacetonitrile. All salts are characterized by vibrational and NMR spectroscopy. 相似文献
7.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1991,47(6):721-725
The structure and 29Si chemical shifts of nine undecamethylcyclohexasilanyl derivatives, Si6Me11X (X = Fe(CO)2cp, SO3CF3, F, Cl, Br, I, H, C CH, OH), have been assigned using 1JSiSi and 2JSiSi derived from 29Si-INADEQUATE and 29Si-INEPT-INADEQUATE and 29Si-INEPT-INADEQUATE NMR spectra. Only the halo-derivatives exhibit linear correlation between 1JSiSi and Pauling electronegativities. The correlation of other derivatives is improved by employing Inamato's inductivity values. A new synthetic route to Si6Me11X (X = F, Cl, Br, I) has been developed. 相似文献
8.
Preparation and Crystal Structures of Dipyridiniomethane Monohalogenohydro-closo-Dodecaborates(2?), [(C5H5N)2CH2][B12H11X]; X = Cl, Br, I [B12H12]2? reacts with dihalogenomethanes CH2X2 in presence of trifluoro acetic acid, yielding the monohalogenododecaborates [B12H11X]2? (X = Cl, Br, I), which are separated by ion exchange chromatography on diethylaminoethyl(DEAE) cellulose from the starting compound and higher halogenated products. The X-ray structure determinations of [(C5H5N)2CH2][B12H11Cl] · 2(CH3)2SO (orthorhombic, space group Pnma, a = 17.351(6), b = 16.034(5), c = 9.659(2) Å, Z = 4) and of the isotypic bromo and iodo compounds [(C5H5N)2CH2][B12H11X] (monoclinic, space group P21/n, Z = 4; for X = Br: a = 7.339(2), b = 15.275(3), c = 16.761(4) Å, β = 96.80(2)°; for X = I: a = 7.4436(8), b = 15.3510(8), c = 16.9213(16) Å, ß = 97.326(7)°) exhibit crystal lattices build up by columns of substituted boron clusters and angular dications [(C5H5N)2CH2]2+ orientated along the shortest axis which are assembled to alternating layers. 相似文献
9.
Ruthenium(II) Phthalocyaninates(2–): Synthesis and Properties of (Acido)(carbonyl)phthalocyaninato(2–)ruthenate(II), [Ru(X)(CO)Pc2?]? (X = Cl, Br, I, NCO, NCS, N3) (nBu4N)[Ru(OH)2Pc2?] is reduced in acetone with carbonmonoxid to blue-violet [Ru(H2O)(CO)Pc2?], which yields in tetrahydrofurane with excess (nBu4N)X acido(carbonyl)phthalocyaninato(2–)ruthenate(II), [Ru(X)(CO)Pc2?]? (X = Cl, Br, I, NCO, NCS, N3) isolated as red-violet, diamagnetic (nBu4N) complex salt. The UV-Vis spectra are dominated by the typical π-π* transitions of the Pc2? ligand at approximately 15100 (B), 28300 (Q1) und 33500 cm?1 (Q2), only fairly dependent of the axial ligands. v(C? O) is observed at 1927 (X = I), 1930 (Cl, Br), 1936 (N3, NCO) 1948 cm?1 (NCS), v(C? N) at 2208 cm?1 (NCO), 2093 cm?1 (NCS) and v(N? N) at 2030 cm?1 only in the MIR spectrum. v(Ru? C) coincides in the FIR spectrum with a deformation vibration of the Pc ligand, but is detected in the resonance Raman(RR) spectrum at 516 (X = Cl), 512 (Br), 510 (N3), 504 (I), 499 (NCO), 498 cm?1 (NCS). v(Ru? X) is observed in the FIR spectrum at 257 (X = Cl), 191 (Br), 166 (I), 349 (N3), 336 (NCO) and 224 cm?1 (NCS). Only v(Ru? I) is RR-enhanced. 相似文献
10.
Thomas Kern Roland Fischer Michaela Flock Karl Hassler 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):931-940
The synthesis and purification of novel bi(silacyclohexyls) C5H10SiX-XSiC5H10 with X = H (1), Ph (2), F (3), Cl (4), Br (5), and I (6), which are composed of two silacyclohexyl rings connected by a silicon–silicon single bond, is described. Molecular structures for 2, 4, 5, and 6 were determined employing X-ray crystallography. Surprisingly, the SiSi bond lengths increase in the order I < Br < Cl, contrary to what is observed for methylated disilanes Me2XSiSiXMe2. The bond lengthening can be traced back to 1, 3 nonbonded interactions between the halogen atoms and the axial hydrogen atoms in the SiC5 ring, which also cause a decrease of the SiSiX bond angles with increasing size of the halogen atom. Both rings substitute each other in the equatorial position for 4, 5, and 6, but in the axial position for 2. 相似文献
11.
Dieter Hauchecorne Dr. Roman Szostak Dr. Wouter A. Herrebout Prof. Benjamin J. van der Veken Prof. 《Chemphyschem》2009,10(12):2105-2115
The formation of weakly bound molecular complexes between dimethyl ether (DME) and the trifluoromethyl halides CF3Cl, CF3Br and CF3I dissolved in liquid argon and in liquid krypton is investigated, using Raman and FTIR spectroscopy. For all halides evidence is found for the formation of C? X???O halogen‐bonded 1:1 complexes. At higher concentrations of CF3Br, a weak absorption due to a 1:2 complex is also observed. Using spectra recorded at temperatures between 87 and 125 K, the complexation enthalpies for the complexes are determined to be ?6.8(3) kJ mol?1 (DME?CF3Cl), ?10.2(1) kJ mol?1 (DME?CF3Br), ?15.5(1) kJ mol?1 (DME?CF3I), and ?17.8(5) kJ mol?1 [DME(?CF3Br)2]. Structural and spectral information on the complexes is obtained from ab initio calculations at the MP2/ 6‐311++G(d,p) and MP2/6‐311++G(d,p)+LanL2DZ* levels. By applying Monte Carlo free energy perturbation calculations to account for the solvent influences, and statistical thermodynamics to estimate the zero‐point vibrational and thermal influences, the ab initio complexation energies are converted into complexation enthalpies for the solutions in liquid argon. The resulting values are compared with the experimental data deduced from the cryosolutions. 相似文献
12.
Total NMR band shape fitting methods have provided accurate energy data for inversion barriers at sulphur and selenium in complexes of types cis-[MX2L] (M = PdII, PtII; X = Cl, Br, I; L = MeS(CH2)2SMe, MeS(CH2)3SMe, o-(SMe)2C6H3Me, cis-MeSCH=CHSMe) and [PtXMe{MeE(CH2)2E′Me}] (E= E′= S or Se and E = S, E′= Se; X = Cl, Br, I). Barrier energies were found to decrease by 10–12 kJ mol?1 in going from aliphatic through aromatic to olefinic ligand back-bone. This can be explained in terms of (3p - 2p) π conjugation between the inverting centre and the ligand back-bone. The effects of ligand ring size, nature of halogen atom and the metal oxidation state on the barrier energies are discussed. 相似文献
13.
The Voronoi–Dirichlet polyhedra (VDP) and the method of intersecting spheres were used to perform crystal-chemical analysis of compounds containing complexes [Os
a
X
b
]
z–(X = F, Cl, Br, I). Atoms of Os(V) at X = F and Cl, of Os(IV) at X = Cl, Br, and of Os(III) at X = Br were found to exhibit a coordination number of 6 with respect to the halogen atoms and to form OsX6octahedra. The coordination polyhedra of Os(III) for X = Cl, I are square pyramids OsX4. Each Os(III) atom forms one Os–Os bond; as a consequence, the OsBr6octahedra share a face in forming Os2Br3–
9complexes, while the OsX4pyramids (X = Cl, I) dimerize to produce [X4Os–OsX4]2–ions. The influence of the valence state of the Os atoms and of the nature of the halogen atoms on the composition and structure of the complexes formed and some characteristics of the coordination sphere of Os were considered. 相似文献
14.
Peter C. Burgers J. L. Holmes F. P. Lossing Frank R. Povel Johan K. Terlouw 《Journal of mass spectrometry : JMS》1983,18(8):335-339
The structures of the m/z 87, [C4H7O2]+, ions generated by dissociative ionization of CH3CGXCOOCH3 and XCH2CH2COOCH3 (X = CH3, Cl, Br, and I) have been investigated via their unimolecular and collisionally activated fragmentations and by apperance energy measurements. For both precursors loss of X = CH3 produced, via H atom transfer, ions of structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH_2 = CH}\mathop {\rm C}\limits^{\rm + } \left({{\rm OH}} \right){\rm OCH}_{\rm 3} $\end{document} (a), ΔHf = 386 kj mol?1. In marked contrast, loss of I˙ from ionized CH3CHICOOCH3 and ICH2CH2COOCH3 proceeded without rearrangement to yield respectively ions of structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH_3}\mathop {\rm C}\limits^{\rm + } {{\rm HCOOCH_3}} $\end{document} (b), ΔHf = 480 kJ mol?1 and (c), ΔHf = 450 kJ mol?1. These different fragmentation behaviours are explained via photoelectron spectra which show that the formal charge site in the precursor ion is at the carbonyl oxygen when X = CH3 but at the halogen atom when X = I. The precursor molecules X = Cl and Br display both of the above characteristics, CH3CHXCOOCH3 yielding mixtures of a and b and XCH2CH2COOCH3 producing a and c ions. 相似文献
15.
Three-coordinate RhX(PCy3)2 complexes (X = F, Cl, Br, I; Cy = cyclohexyl) have been prepared from rhodium(I) cyclooctene compounds. RhCl(PCy3)2 is in equilibrium with its dimer. The complexes RhX(PCy3)2 (X = Cl, Br, I) form the adducts RhX(PCy3)2(N2) with dinitrogen, the times for N2-fixation being 4 days, 3 hours and 15 minutes respectively. The three-coordinate complexes form four-coordinate dioxygen adducts RhX(PCy3)2(O2) which have unusually high ν(OO) at about 990 cm?1. This high frequency is attributed to the four-coordination, which is exceptional for dioxygen complexes. From RhF(PCy3)2 carbonyl, ethene, and diphenylacetylene complexes RhX(PCy3)2L (X = F, Cl, Br, I, N3, NCO, NCS; L = CO, C2H4, C2Ph2) (X = CN, NO3, acetate; L = CO) have been prepared. The trans-influence of the anionic ligands on the infrared frequencies of the neutral ligands is discussed in terms of the different π-bonding properties of the X- and L-ligands. 相似文献
16.
Feng‐You Hao Yong‐Fang Zhao Xiao‐Gong Jing Xin‐Ying Li Feng‐Li Liu 《International journal of quantum chemistry》2007,107(6):1502-1507
Ab initio quantum chemical calculations have been performed on X2Cl? and X2Cl (X = C, Si, Ge) clusters. The geometrical structures, vibrational frequencies, electronic properties and dissociation energies are investigated at the Hartree–Fock (HF), Møller–Plesset second‐ and fourth‐order (MP2, MP4), CCSD(T) level with the 6‐311+G(d) basis set. The X2Cl (X = C, Si, Ge) and X2Cl? (X = Si, Ge) take a bent shape obtained at the ground state, while C2Cl? has a linear structure. The impact on internal electron transfer between the X2Cl and the corresponding anional clusters is studied. The three different types of electron affinities (EAs) at the CCSD(T) are reported. The most reliable adiabatic electronic affinities, obtained at the CCSD(T)/cc‐pvqz level of theory, are predicted to be 3.30, 2.62, and 1.98 eV for C2Cl, Si2Cl, and Ge2Cl, respectively. The calculated EAs of C2Cl and Ge2Cl are in good agreement with theoretical results reported. The correlation effects and basis sets effects on the geometrical structures and dissociation energies are discussed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
17.
Maria V. Kashina Mikhail A. Kinzhalov Andrey S. Smirnov Daniil M. Ivanov Alexander S. Novikov Vadim Yu. Kukushkin 《化学:亚洲杂志》2019,14(21):3915-3920
The dihalomethanes CH2X2 (X=Cl, Br, I) were co‐crystallized with the isocyanide complexes trans‐[MXM2(CNC6H4‐4‐XC)2] (M=Pd, Pt; XM=Br, I; XC=F, Cl, Br) to give an extended series comprising 15 X‐ray structures of isostructural adducts featuring 1D metal‐involving hexagon‐like arrays. In these structures, CH2X2 behave as bent bifunctional XB/XB‐donating building blocks, whereas trans‐[MXM2(CNC6H4‐4‐XC)2] act as a linear XB/XB acceptors. Results of DFT calculations indicate that all XCH2–X???XM–M contacts are typical noncovalent interactions with estimated strengths in the range of 1.3–3.2 kcal mol?1. A CCDC search reveals that hexagon‐like arrays are rather common but previously overlooked structural motives for adducts of trans‐bis(halide) complexes and halomethanes. 相似文献
18.
Davood Nori-Shargh Arezoo Khamooshi-Sarabi Sasan Sharifi Elham Sheikh-Ansari 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2122-2134
NBO analysis and hybrid density functional theory–based method (B3LYP/6-311+G**) was used to study the anomeric effects (AE), dipole–dipole interactions, and steric repulsion effects on the conformational properties of 2,3,5,6-tetrahalo-1,4-dioxane [halo = F (1), Cl (2), Br (3)], 2,3,5,6-tetrahalo-1,4-dithiane [halo = F (4), Cl (5), Br (6)], and 2,3,5,6-etrahalo-1,4-diselenane [halo = F (7), Cl (8), Br (9)]. B3LYP/6-311+G** results revealed a strong axial preference in compounds 1–3. Gibbs free energy difference (G eq–G ax) values (e.g., ΔG eq-ax) between the axial and equatorial conformations of compound 1 to compound 3 are 8.19, 3.86, and 3.13 kcal mol?1, respectively, as calculated by the B3LYP/6-311+G** level of theory. On the other hand, the NBO analysis of donor–acceptor (bond–antibond) interactions revealed that the AE for compounds 1–3 are ?12.26, ?16.46, and ?18.11 kcal mol?1, respectively. Contrary to the increase of the AE values from compound 1 to compound 3, the increase of the steric repulsions (e.g., 1,3-syn-axial repulsions) could fairly explain the decrease of the axial conformation stability in compounds 1–3 compared to their equatorial conformations. Further, the correlations between the AE, structural parameters, and conformational behavior of compounds 4–9 have been investigated. 相似文献
19.
Dr. Martin Mayer Dr. Markus Rohdenburg Sebastian Kawa Francine Horn Harald Knorke Prof. Dr. Carsten Jenne Prof. Dr. Ralf Tonner Prof. Dr. Knut R. Asmis Dr. Jonas Warneke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(40):10274-10281
Electrophilic anions of type [B12X11]− posses a vacant positive boron binding site within the anion. In a comparatitve experimental and theoretical study, the reactivity of [B12X11]− with X=F, Cl, Br, I, CN is characterized towards different nucleophiles: (i) noble gases (NGs) as σ-donors and (ii) CO/N2 as σ-donor-π-acceptors. Temperature-dependent formation of [B12X11NG]− indicates the enthalpy order (X=CN)>(X=Cl)≈(X=Br)>(X=I)≈(X=F) almost independent of the NG in good agreement with calculated trends. The observed order is explained by an interplay of the electron deficiency of the vacant boron site in [B12X11]− and steric effects. The binding of CO and N2 to [B12X11]− is significantly stronger. The B3LYP 0 K attachment enthapies follow the order (X=F)>(X=CN)>(X=Cl)>(X=Br)>(X=I), in contrast to the NG series. The bonding motifs of [B12X11CO]− and [B12X11N2]− were characterized using cryogenic ion trap vibrational spectroscopy by focusing on the CO and N2 stretching frequencies and , respectively. Observed shifts of and are explained by an interplay between electrostatic effects (blue shift), due to the positive partial charge, and by π-backdonation (red shift). Energy decomposition analysis and analysis of natural orbitals for chemical valence support all conclusions based on the experimental results. This establishes a rational understanding of [B12X11]− reactivety dependent on the substituent X and provides first systematic data on π-backdonation from delocalized σ-electron systems of closo-borate anions. 相似文献
20.
IR spectra of 2-haloethanols (CH2XCH2OH, X = Cl, Br, and I) in carbon disulfide were measured at 25°C up to 2.5 kbar. The volume changes accompanying the transformation to the Gg conformer of the compounds were ?1.2, +0.5, and +1.3 cm3 mol?1 for X = Cl, Br, and I, respectively. 相似文献