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1.
Thermochemical properties for reactants, intermediates, products, and transition states important in the ketene (CH2?C?O) + H reaction system and unimolecular reactions of the stabilized formyl methyl (C·H2CHO) and the acetyl radicals (CH3C·O) were analyzed with density functional and ab initio calculations. Enthalpies of formation (ΔHf°298) were determined using isodesmic reaction analysis at the CBS‐QCI/APNO and the CBSQ levels. Entropies (S°298) and heat capacities (Cp°(T)) were determined using geometric parameters and vibrational frequencies obtained at the HF/6‐311G(d,p) level of theory. Internal rotor contributions were included in the S and Cp(T) values. A hydrogen atom can add to the CH2‐group of the ketene to form the acetyl radical, CH3C·O (Ea = 2.49 in CBS‐QCI/APNO, units: kcal/mol). The acetyl radical can undergo β‐scission back to reactants, CH2?C?O + H (Ea = 45.97), isomerize via hydrogen shift (Ea = 46.35) to form the slight higher energy, formyl methyl radical, C·H2CHO, or decompose to CH3 + CO (Ea = 17.33). The hydrogen atom also can add to the carbonyl group to form C·H2CHO (Ea = 6.72). This formyl methyl radical can undergo β scission back to reactants, CH2?C?O + H (Ea = 43.85), or isomerize via hydrogen shift (Ea = 40.00) to form the acetyl radical isomer, CH3C·O, which can decompose to CH3 + CO. Rate constants are estimated as function of pressure and temperature, using quantum Rice–Ramsperger–Kassel analysis for k(E) and the master equation for falloff. Important reaction products are CH3 + CO via decomposition at both high and low temperatures. A transition state for direct abstraction of hydrogen atom on CH2?C?O by H to form, ketenyl radical plus H2 is identified with a barrier of 12.27, at the CBS‐QCI/APNO level. ΔHf°298 values are estimated for the following compounds at the CBS‐QCI/APNO level: CH3C·O (?3.27), C·H2CHO (3.08), CH2?C?O (?11.89), HC·CO (41.98) (kcal/mol). © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 35: 20–44, 2003  相似文献   

2.
The title compounds, C14H12N+·CH3O4S?, (I), and C15H14N+·CH3O4S?, (II), respectively, crystallize with the planar 10‐methylacridinium or 9,10‐di­methyl­acridinium cations arranged in layers, parallel to the twofold axis in (I) and perpendicular to the 21 axis in (II). Adjacent cations in both compounds are packed in a `head‐to‐tail' manner. The methyl sulfate anion only exhibits planar symmetry in (II). The cations and anions are linked through C—H?O interactions involving three O atoms of the anion, six acridine H atoms and the CH3 group on the N atom in (I), and the four O atoms of the anion, three acridine H atoms and the carbon‐bound CH3 group in (II). The methyl sulfate anions are oriented differently in the two compounds relative to the cations, being nearly perpendicular in (I) but parallel in (II). Electrostatic interaction between the ions and the network of C—H?O interactions leads to relatively compact crystal lattices in both structures.  相似文献   

3.
In the title compound, [(CH3)2(C7H7)NH][(C6F5)3B(OH)] or C9H14N+·C18HBF15O?, the distorted tetrahedral borate anions are strongly hydrogen bonded to the substituted ammonium cations. The N?O separation in the N—H?O hydrogen bond is 2.728 (3) Å.  相似文献   

4.
Using four basis sets, 6‐311G(d,p), 6‐31+G(d,p), 6‐311++G(2d,2p), and 6‐311++G(3df,3pd), the optimized structures with all real frequencies were obtained at the MP2 level for dimers CH2O? HF, CH2O? H2O, CH2O? NH3, and CH2O? CH4. The structures of CH2O? HF, CH2O? H2O, and CH2O? NH3 are cycle‐shaped, which result from the larger bend of σ‐type hydrogen bonds. The bend of σ‐type H‐bond O…H? Y (Y?F, O, N) is illustrated and interpreted by an attractive interaction of a chemically intuitive π‐type hydrogen bond. The π‐type hydrogen bond is the interaction between one of the acidic H atoms of CH2O and lone pair(s) on the F atom in HF, the O atom in H2O, or the N atom in NH3. By contrast with above the three dimers, for CH2O? CH4, because there is not a π‐type hydrogen‐bond to bend its linear hydrogen bond, the structure of CH2O? CH4 is a noncyclic shaped. The interaction energy of hydrogen bonds and the π‐type H‐bond are calculated and discussed at the CCSD(T)/6‐311++G(3df,3pd) level. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005  相似文献   

5.
The crystal structure of a methanol–water solvate ofleurosine me­thio­dide, (leurosine‐CH3)+I?·3CH3OH·2H2O (C47H59IN4O9·3CH3OH·2H2O), is described. The piperidine ring of the upper part of the mol­ecule adopts a sofa conformation. An intramolecular hydrogen bond between the tertiary N and the hydroxyl group of the vindoline moiety of the mol­ecule is present.  相似文献   

6.
The crystal structure of 4‐(3‐carboxy‐1‐ethyl‐6‐fluoro‐1,4‐di­hydro‐4‐oxo‐7‐quinolyl)‐1‐methyl­piperazinium methane­sulfonate 0.10‐hydrate, C17H21FN3O3+·CH3O3S?·0.10H2O, contains pefloxacinium cations, methane­sulfonate anions and a partially occupied water of solvation. The quinoline ring system in the cation is essentially planar. The anions lie parallel to each other about inversion centers. The structure is stabilized by strong hydrogen bonds involving the terminal piperazinyl‐N atom of the cation and an O atom of the anion [N?O 2.739 (2) Å], and a strong intramolecular hydrogen bond between carbonyl and carboxyl groups [O?O 2.523 (2) Å].  相似文献   

7.
The title compound, C7H8FO6PS·H2O, contains both phospho­nic and sulfonic acid functionalities. An extensive network of O—H?O hydrogen bonds is present in the crystal structure. The three acidic protons are associated with the phospho­nate group. Two protons experience typical hydrogen‐bond contacts with the sulfonate‐O atoms, while the third has a longer covalent bond of 1.05 (3) Å to the phospho­nate‐O atom and a short hydrogen‐bond contact of 1.38 (3) Å to the water O atom (all O—H?O angles are in the range 162–175°). The sulfonate group is positioned so that one S—O bond is nearly coplanar with the phenyl ring [torsion angle O—S—C—C ?8.6 (2)°]. The phospho­nate group is oriented approximately perpendicular to the ring [torsion angle P—C—C—C 99.2 (2)°] with one P—O bond anti to the benzyl C—C bond. The mol­ecules pack in layers in the bc plane with the water mol­ecules in between adjacent pairs of inverted layers.  相似文献   

8.
Using four basis bets, (6‐311G(d,p), 6‐31+G(d,p), 6‐31++G(2d,2p), and 6‐311++G(3df,3pd), the optimized structures with all real frequencies were obtained at the MP2 level for the dimers CH2O? HF, CH2O? H2O, CH2O? NH3, and CH2O? CH4. The structures of CH2O? HF, CH2O? H2O, and CH2O? NH3 are cycle‐shaped, which result from the larger bend of σ‐type hydrogen bonds. The bend of σ‐type H‐bond O…H? Y (Y?F, O, N) is illustrated and interpreted by an attractive interaction of a chemically intuitive π‐type hydrogen bond. The π‐type hydrogen bond is the interaction between one of the H atoms of CH2O and lone pair(s) on the F atom in HF, the O atom in H2O, or the N atom in NH3. In contrast with the above three dimers, for CH2O? CH4, because there is not a π‐type hydrogen bond to bend its linear hydrogen bond, the structure of CH2O? CH4 is noncyclic shaped. The interaction energy of hydrogen bonds and the π‐type H‐bond are calculated and discussed at the CCSD (T)/6‐311++G(3df,3pd) level. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005  相似文献   

9.
The title compound, C21H18O2, crystallized in the centrosymmetric space group P21/n with one mol­ecule in the asymmetric unit. There is a single hydrogen bond, with an Odonor?Oacceptor distance of 2.624 (2) Å, which forms a cyclic dimer about a center of symmetry. The carboxyl group O atoms are ordered, while the carboxyl‐H atom is disordered. A single leading intermolecular C—H?O interaction has an H?O distance of 2.68 Å and a C—H?O angle of 178°; this interaction forms chains. Taken together with the hydrogen bond, it generates chains and rings. Structural comparisons are made with trans‐cinnamic acid and with 4‐methyl‐trans‐cinnamic acid.  相似文献   

10.
In the crystal structures of both title compounds, [1,3‐bis(2‐hydroxybenzylidene)‐2‐methyl‐2‐(2‐oxidobenzylideneaminomethyl)propane‐1,3‐diamine]nickel(II) [2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methyl‐1,3‐bis(2‐oxidobenzylidene)propane‐1,3‐diamine]nickel(II) chloride methanol disolvate, [Ni(C26H25.5N3O3)]2Cl·2CH4O, and [1,3‐bis(2‐hydroxybenzylidene)‐2‐methyl‐2‐(2‐oxidobenzylideneaminomethyl)propane‐1,3‐diamine]zinc(II) perchlorate [2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methyl‐1,3‐bis(2‐oxidobenzylidene)propane‐1,3‐diamine]zinc(II) methanol trisolvate, [Zn(C26H25N3O3)]ClO4·[Zn(C26H26N3O3)]·3CH4O, the 3d metal ion is in an approximately octahedral environment composed of three facially coordinated imine N atoms and three phenol O atoms. The two mononuclear units are linked by three phenol–phenolate O—H...O hydrogen bonds to form a dimeric structure. In the Ni compound, the asymmetric unit consists of one mononuclear unit, one‐half of a chloride anion and a methanol solvent molecule. In the O—H...O hydrogen bonds, two H atoms are located near the centre of O...O and one H atom is disordered over two positions. The NiII compound is thus formulated as [Ni(H1.5L)]2Cl·2CH3OH [H3L is 1,3‐bis(2‐hydroxybenzylidene)‐2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methylpropane‐1,3‐diamine]. In the analogous ZnII compound, the asymmetric unit consists of two crystallographically independent mononuclear units, one perchlorate anion and three methanol solvent molecules. The mode of hydrogen bonding connecting the two mononuclear units is slightly different, and the formula can be written as [Zn(H2L)]ClO4·[Zn(HL)]·3CH3OH. In both compounds, each mononuclear unit is chiral with either a Δ or a Λ configuration because of the screw coordination arrangement of the achiral tripodal ligand around the 3d metal ion. In the dimeric structure, molecules with Δ–Δ and Λ–Λ pairs co‐exist in the crystal structure to form a racemic crystal. A notable difference is observed between the M—O(phenol) and M—O(phenolate) bond lengths, the former being longer than the latter. In addition, as the ionic radius of the metal ion decreases, the M—O and M—N bond distances decrease.  相似文献   

11.
The cation of the title compound, C12H15N2O+·CF3SO3?, exists as an E‐configured hydroxy­imino derivative conjugated with a nearly planar iminium system. The twist angle between the phenyl ring and the oxime group is 72.2 (2)°. An O—H?O hydrogen bond links the oxime group of the cation to the anion.  相似文献   

12.
A bimolecular rate constant,kDHO, of (29 ± 9) × 10?12 cm3 molecule?1 s?1 was measured using the relative rate technique for the reaction of the hydroxyl radical (OH) with 3,5‐dimethyl‐1‐hexyn‐3‐ol (DHO, HC?CC(OH)(CH3)CH2CH(CH3)2) at (297 ± 3) K and 1 atm total pressure. To more clearly define DHO's indoor environment degradation mechanism, the products of the DHO + OH reaction were also investigated. The positively identified DHO/OH reaction products were acetone ((CH3)2C?O), 3‐butyne‐2‐one (3B2O, HC?CC(?O)(CH3)), 2‐methyl‐propanal (2MP, H(O?)CCH(CH3)2), 4‐methyl‐2‐pentanone (MIBK, CH3C(?O)CH2CH(CH3)2), ethanedial (GLY, HC(?O)C(?O)H), 2‐oxopropanal (MGLY, CH3C(?O)C(?O)H), and 2,3‐butanedione (23BD, CH3C(?O)C(?O)CH3). The yields of 3B2O and MIBK from the DHO/OH reaction were (8.4 ± 0.3) and (26 ± 2)%, respectively. The use of derivatizing agents O‐(2,3,4,5,6‐pentalfluorobenzyl)hydroxylamine (PFBHA) and N,O‐bis(trimethylsilyl)trifluoroacetamide (BSTFA) clearly indicated that several other reaction products were formed. The elucidation of these other reaction products was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible DHO/OH reaction mechanisms based on previously published volatile organic compound/OH gas‐phase reaction mechanisms. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 534–544, 2004  相似文献   

13.
The binuclear cation of the title compound, [Ni2(C33H29­N4O3)(H2O)4]C2H3O2·C3H7NO·0.75H2O, was synthesized as a model for the active site of urease. Two tridentate halves of the symmetrical 2,6‐bis{[(2‐hydroxy­phenyl)(2‐pyridyl­methyl)­amino]­methyl}‐4‐methyl­phenolate (BPPMP3?) ligand are arranged in a meridional fashion around the two NiII ions, with the phenoxo O atom bridging the NiII ions. The cation has an approximate twofold rotation axis running through the C—O bond of the bridging phenolate group. Four water mol­ecules complete the octahedral environment of each NiII ion.  相似文献   

14.
In 3‐methyl­thio‐4‐(propargyl­thio)­quinolinium chloride monohydrate, C13H12NS2+·Cl?·H2O, and 3‐methyl­thio‐4‐(propargyl­thio)­quinolinium tri­chloro­acetate, C13H12­NS2+·­C2Cl3O2?, the terminal alkyne group forms C[triple‐bond]C—H?O hydrogen bonds of favourable geometry. The conformation of the flexible propargyl­thio group is different in the two structures.  相似文献   

15.
A centrosymmetric and short O—H?O hydrogen bond was found in isomorphic crystals of potassium hydrogen trans‐glutaconate monohydrate (potassium hydrogen trans‐pent‐2‐ene‐1,5‐dioate, K+·C5H5O4?·H2O), (I), and rubidium hydrogen trans‐glutaconate monohydrate (rubidium hydrogen trans‐pent‐2‐ene‐1,5‐dioate, Rb+·C5H5O4?·H2O), (II). The O?O distance at room temperature is 2.444 (3) Å in (I), and 2.417 (4) Å in (II). The O?O distance for (I) showed no significant decrease at low temperatures.  相似文献   

16.
The title compound, meso‐5,7,7,12,14,14‐hexa­methyl‐4,11‐di­aza‐1,8‐diazo­nia­cyclo­tetra­decane bis(3‐carboxy‐5‐nitro­benz­oate), C16H38N42+·2C8H4NO6?, is a salt in which the cation is present as two configurational isomers, disordered across a common centre of inversion in P, with occupancies of 0.847 (3) and 0.153 (3). The anions are linked into chains by a single O—H?O hydrogen bond [H?O 1.71 Å, O?O 2.5063 (15) Å and O—H?O 156°] and the cations link these anion chains into sheets by means of a range of N—H?O hydrogen bonds [H?O 1.81–2.53 Å, N?O 2.718 (5)–3.3554 (19) Å and N—H?O 146–171°].  相似文献   

17.
Solvent‐free (2S)‐methyl 2‐ammonio‐3‐(4‐hydroxy­phenyl)­propionate chloride, C10H14NO3+·Cl, (I), and its methanol solvate, C10H14NO3+·Cl·CH3OH, (II), are obtained from different solvents: crystallization from ethanol or propan‐2‐ol gives the same solvent‐free crystals of (I) in both cases, while crystals of (II) were obtained by crystallization from methanol. The structure of (I) is characterized by the presence of two‐dimensional layers linked together by N—H⋯Cl and O—H⋯Cl hydrogen bonds and also by C—H⋯O contacts. Incorporation of the methanol solvent mol­ecule in (II) introduces additional O—H⋯O hydrogen bonds linking the two‐dimensional layers, resulting in the formation of a three‐dimensional network.  相似文献   

18.
Quantum calculations at the MP2/aug‐cc‐pVDZ level are used to analyze the SH···N H‐bond in complexes pairing H2S and SH radical with NH3, N(CH3)3, NH2NH2, and NH2N(CH3)2. Complexes form nearly linear H‐bonds in which the S? H covalent bond elongates and shifts its stretching frequency to the red. Binding energies vary from 14 kJ/mol for acceptor NH3 to a maximum of 22 kJ/mol for N(CH3)3 and N(CH3)2NH2. Analysis of geometric, vibrational, and electronic data indicate that the SH···N interaction involving SH is slightly stronger than that in which the closed‐shell H2S serves as donor. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011  相似文献   

19.
The 2,8‐di­hydroxy‐1,3,7,9‐tetra­methyl‐6,12‐di­hydro­di­pyrido[1,2‐a:1′,2′‐d]pyrazine­diyl­ium dication possesses 2/m symmetry and lies in the mirror plane together with a chloride anion and the water O atom. The dication also lies on an inversion centre, i.e. C16H20N2O22+·2Cl?·2H2O. Due to these symmetry constrictions the dication adopts an unexpected planar conformation. Molecules are linked by O—H?O and O—H?Cl hydrogen bonds to form chains, which are cross‐connected by C—H?Cl attractive interactions forming a complex three‐dimensional hydrogen‐bond network.  相似文献   

20.
The title structure, [Rh2(C7H5O3)4(C2H6OS)2]·[Rh2(C4H7­O2)4(C2H6OS)2]·2C2H6O, contains two discrete neutral Rh–Rh dimers cocrystallized as the ethanol disolvate. Each dimer is situated on an inversion center. The butyrate chain displays disorder in one C‐atom position. In each dimer, the di­methyl sulfoxide ligand (dmso) is bound via S, as expected. The ethanol is a hydrogen‐bond acceptor for one p‐hydroxy­benzoate hydroxyl group and acts as a hydrogen‐bond donor to the dmso O atom of a neighboring p‐hydroxy­benzoate dirhodium complex. A third hydrogen bond is formed from the other p‐hydroxy­benzoate hydroxyl group to the dmso O atom of a butyrate–dirhodium complex.  相似文献   

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