Isomers on the C2H2Cl+ surface. Calculated enthalpies of formation for unsaturated hydrocarbons and monochloro derivatives

Rodriquez, Christopher F.; Böhme, Diethard K.; Hopkinson, Alan C.

doi:10.1021/jo00064a021

Cited by 21 publications

(23 citation statements)

References 4 publications

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“…For structures I , III , V , and VII , three levels of theory were used to calculate the standard enthalpies of formation at 298 K. The results are summarized in Table . It has been shown previously that enthalpies of formation obtained at MP4SDTQ(fc)/6-311++G(2df,p) are within ±2 kcal mol -1 of experimental values. , The single-point DFT calculations at B3LYP/ 6-311++G(2df,p) yield values of comparable accuracy that are lower than the MP4 enthalpies by at most 1.4 kcal mol -1 for structures I and III . Calculations for the larger structures V and VII were restricted to DFT calculations with the 6-31+G* basis set.…”

Section: Theoretical Resultssupporting

confidence: 60%

Sequential Ligation of Mg⁺, Fe⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)Fe⁺ with Ammonia in the Gas Phase: Transition from Coordination to Solvation in the Sequential Ligation of Mg⁺

et al. 1998

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Experimental results are reported that track the kinetics of the sequential ligation of Mg+, Fe+, (c-C5H5)Mg+, and (c-C5H5)Fe+ with ammonia in the gas phase as a function of the number of ligands added. The energetics of the sequential ligation of Mg+ with ammonia has also been followed theoretically. Molecular orbital calculations with density functional theory (DFT) performed at the B3LYP/6-31+G(d) level have been used to compute the binding energies for direct coordination of the ammonia molecules with Mg+ and for solvation that involves N−H···N interactions. Single-point calculations were also done using the optimized geometries from B3LYP/6-31+G(d) at B3LYP/6-311++G(2df,p) and MP4SDTQ(fc)/6-311++G(2df,p). Relative binding energies and standard enthalpies of formation (ΔH°f,298) have been calculated at all three levels of theory investigated. The experiments were performed with a selected-ion flow tube (SIFT) apparatus in helium buffer gas at 0.35 ± 0.01 Torr and 294 ± 3 K. The measured rate coefficients for ligation of both atomic metal ions exhibit a maximum for the second addition of ammonia, which disappears in the presence of a c-C5H5 substituent as the rate of ligation of Mg+ and Fe+ is enhanced by about 2 orders of magnitude. These trends have been interpreted in terms of the dependence of the lifetime of the collision intermediate on its degrees of freedom and the depth of its potential energy well. For the ligation of Mg+, we propose that the precipitous drop in the observed rate of ligation of the fourth ligand and the emergence of a weakly bonded population of ligated ions in measured multicollision-induced dissociation spectra for Mg(NH3)3 + and Mg(NH3)4 + may signify a change in the nature of the bonding from direct bonding to hydrogen bonding in a second coordination shell with the addition of the third ligand. The observed variations in onset energy for multicollision-induced dissociation generally are consistent with a negative trend in the ligation energy with increasing ligation for the four ligated systems investigated.

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Section: Theoretical Resultssupporting

confidence: 60%

Sequential Ligation of Mg⁺, Fe⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)Fe⁺ with Ammonia in the Gas Phase: Transition from Coordination to Solvation in the Sequential Ligation of Mg⁺

et al. 1998

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“…They found that exchange does occur in certain cases but that the predominant reaction is a competing process which is completely unrelated to exchange. 8 The structures of the chloriranium and chlorirenium ions have been addressed theoretically [9][10][11][12][13] and, in a computational study, we have investigated the πligand exchange reaction for these systems 13 and found results similar to those obtained previously for the phosphorus and sulfur systems. 3,14 The gas-phase reaction between ammonia and a chloriranium ion has been examined experimentally by Bohme et al 15 and Beauchamp et al 16 We had predicted the corresponding phosphorus reaction to be exothermic and to proceed without an overall barrier.…”

Section: Introductionsupporting

confidence: 68%

Exchange of Cl⁺ between Lone-Pair Donors and π-Donors: A Computational Study

Sølling

Radom

2000

Eur J Mass Spectrom (Chichester)

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The chemistry of mono-adducts ([Cl–X]+) between Cl+ and a Lewis base (X = NH3, H2O, HF, PH3, H2S or HCl) has been investigated using ab initio molecular orbital calculations at the G2 level. The reactions of such mono-adducts with additional Lewis bases (Y) are found to give [Y–Cl]+ plus X, generally without an intermediate barrier, via a bis-adduct [Y–Cl–X]+. The binding energies of the bis-adduct and the reaction energies are related to the donor properties of the Lewis bases. The reactions between the mono-adducts [Cl–X]+ and the π-donors ethylene and acetylene yield chloriranium and chlorirenium ions, respectively. These reactions proceed via complexes that resemble either the reactants or products depending on the sign of the reaction energy, the latter in turn being determined by the donor ability of the Lewis base. Results for the chlorine systems are compared with those for the corresponding phosphorus systems investigated previously.

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“…Combining eqs. (8,9) into eq. ( 10), however, we can eliminate the ethyl chloride value: again considering that we are dealing with a simple isodesmic reaction, the experimentally derived ∆H r =-6.49 kcal/mol is rather hard to reconcile with the W1 value of -7.97 kcal/mol.…”

Section: Resultsmentioning

confidence: 99%

“…While there have been numerous studies on saturated halocarbons, there is a paucity of thermochemical data for haloacetylenes and the available data are inconsistent. For example, Colegrove and Thompson [7] evaluated the heats of formation of several chlorinated hydrocarbons in which they reported the ∆H f 298 of HCCH as 56.47 and 56.24 kcal/mol at the G1 and G2 theories respectively, while Rodriquez et al [8] found the enthalpies of formation at 298 K for HCCH and HCCCl at the MP4STDQ/6-311G(2df,p) level as 51.7 and 51.4 kcal/mol respectively.…”

Section: Introductionmentioning

confidence: 99%

The heats of formation of the haloacetylenes XCCY [X, Y = H, F, Cl]: basis set limitab initioresults and thermochemical analysis

2002

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The heats of formation of haloacetylenes are evaluated using the recent W1 and W2 ab initio computational thermochemistry methods. These calculations involve CCSD and CCSD(T) coupled cluster methods, basis sets of up to spdfgh quality, extrapolations to the one-particle basis set limit, and contributions of inner-shell correlation, scalar relativistic effects, and (where relevant) first-order spin-orbit coupling. The heats of formation determined using W2 theory are: ∆H f 298 (HCCH) = 54.48 kcal/mol, ∆H f 298 (HCCF) = 25.15 kcal/mol, ∆H f 298 (FCCF) = 1.38 kcal/mol, ∆H f 298 (HCCCl) = 54.83 kcal/mol, ∆H f 298 (ClCCCl) = 56.21 kcal/mol, and ∆H f 298 (FCCCl) = 28.47 kcal/mol. Enthalpies of hydrogenation and destabilization energies relative to acetylene were obtained at the W1 level of theory. So doing we find the following destabilization order for acetylenes: FCCF > ClCCF > HCCF > ClCCCl > HCCCl > HCCH. By a combination of W1 theory and isodesmic reactions, we show that the generally accepted heat of formation of 1,2-dichloroethane should be revised to -31.8±0.6 kcal/mol, in excellent agreement with a very recent critically evaluated review. The performance of compound thermochemistry schemes such as G2, G3, G3X and CBS-QB3 theories has been analyzed.

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Isomers on the C2H2Cl+ surface. Calculated enthalpies of formation for unsaturated hydrocarbons and monochloro derivatives

Cited by 21 publications

References 4 publications

Sequential Ligation of Mg⁺, Fe⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)Fe⁺ with Ammonia in the Gas Phase: Transition from Coordination to Solvation in the Sequential Ligation of Mg⁺

Sequential Ligation of Mg⁺, Fe⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)Fe⁺ with Ammonia in the Gas Phase: Transition from Coordination to Solvation in the Sequential Ligation of Mg⁺

Exchange of Cl⁺ between Lone-Pair Donors and π-Donors: A Computational Study

The heats of formation of the haloacetylenes XCCY [X, Y = H, F, Cl]: basis set limitab initioresults and thermochemical analysis

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Isomers on the C2H2Cl+ surface. Calculated enthalpies of formation for unsaturated hydrocarbons and monochloro derivatives

Cited by 21 publications

References 4 publications

Sequential Ligation of Mg+, Fe+, (c-C5H5)Mg+, and (c-C5H5)Fe+ with Ammonia in the Gas Phase: Transition from Coordination to Solvation in the Sequential Ligation of Mg+

Sequential Ligation of Mg+, Fe+, (c-C5H5)Mg+, and (c-C5H5)Fe+ with Ammonia in the Gas Phase: Transition from Coordination to Solvation in the Sequential Ligation of Mg+

Exchange of Cl+ between Lone-Pair Donors and π-Donors: A Computational Study

The heats of formation of the haloacetylenes XCCY [X, Y = H, F, Cl]: basis set limitab initioresults and thermochemical analysis

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Product

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About

Sequential Ligation of Mg⁺, Fe⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)Fe⁺ with Ammonia in the Gas Phase: Transition from Coordination to Solvation in the Sequential Ligation of Mg⁺

Sequential Ligation of Mg⁺, Fe⁺, (c-C₅H₅)Mg⁺, and (c-C₅H₅)Fe⁺ with Ammonia in the Gas Phase: Transition from Coordination to Solvation in the Sequential Ligation of Mg⁺

Exchange of Cl⁺ between Lone-Pair Donors and π-Donors: A Computational Study