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1.
The structures and stability of pentacoordinate germylenoid PhCH2(NH2)CH3GeLiF were first theoretically studied by density functional theory. Two equilibrium structures, the three-membered ring and
the p-complex structures, were located. The three-membered ring structure is more stable both in vacuum and in solvents (ether,
THF, and acetone). The Ge–N coordination energies at the B3LYP/6-311+G(d,p) level are 35.8 and 7.9 kJ/mol in the three-membered
ring and the p-complex structures, respectively. The insertion reactions with CH3F indicate that germylenoid PhCH2(NH2)CH3GeLiF is more stable than germylene PhCH2(NH2)CH3Ge. The insertion barrier of PhCH2(NH2)CH3GeLiF with CH3F is higher than that of PhCH3CH3GeLiF, indicating that the amine coordination make PhCH2(NH2)CH3GeLiF more stable. 相似文献
2.
The structures of pentacoordinate silylenoid PhCH2(NH2)CH3SiLiF were studied by density functional theory at the B3LYP/6-31G(d) level. Three equilibrium structures, the three-membered
ring (1), the p-complex (2), and the σ-complex (3) structures, were located. Their energies are in the order of 2 > 1 > 3 both in vacuum and in THF. To exploit the stability of PhCH2(NH2)CH3SiLiF, the insertion reactions of 1 and PhCH2(NH2)CH3Si into C–F have been investigated, respectively. The results show that the insertion of PhCH2(NH2)CH3Si is more favorable. To probe the influence of amine-coordination to the stability of PhCH2(NH2)CH3SiLiF, the insertion reaction of PhCH3CH3SiLiF was also investigated. The calculations indicate that the insertion of PhCH3CH3SiLiF is more favorable than that of 1. So the N atom plays an important role on the stability of silylenoid PhCH2(NH2)CH3SiLiF. 相似文献
3.
Xiaojun Tan Weihua Wang Ping Li Fei Liu 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(8):1355-1362
The geometries and isomerization of the alkylidene germylenoid H2C=GeLiF as well as its insertion reactions with R-H (R = F, OH, NH2, CH3) have been systematically investigated at the B3LYP/6-311+ G* level of theory. The potential barriers of the four insertion
reactions are 110.6, 145.0, 179.4, and 250.6 kJ/mol, respectively. Here, all the mechanisms of the four reactions are identical
to each other, i.e., an intermediate has been formed first during the insertion reaction. Then, the intermediate could dissociate
into the substituted germylene (H2C=GeHR) and LiF with a barrier corresponding to their respective dissociation energies. Correspondingly, the reaction energies
for the four reactions are 43.6, 78.8, 113.5, and 128.0 kJ/mol, respectively. Compared with the insertion reaction of H2C= Ge∶ and R-H, the introduction of LiF makes the insertion reaction occur more difficultly. Furthermore, the effects of halogen
(F, Cl, Br) substitution and inorganic salts employed on the reaction activity have also been discussed. As a result, the
relative reactivity among the four insertion reactions should be as follows: H-F > H-OH > H-NH2 > H-CH3. 相似文献
4.
Jia-xu Zhang Ze-sheng Li Jing-yao Liu Chia-chung Sun 《Theoretical chemistry accounts》2007,117(4):579-586
The radical–molecule reaction mechanism of CH2Cl with NO2 has been explored theoretically at the B3LYP/6–311G(d,p) and MC–QCISD (single-point) levels of theory. Our results indicate that the title reaction proceeds mostly through singlet
pathways, less go through triplet pathways. The initial association between CH2Cl and NO2 is found to be the carbon-to-nitrogen attack forming the adduct a H2ClCNO2 with no barrier, followed by isomerization to b
1
H2ClCONO-trans which can easily convert to b
2
H2ClCONO-cis. Subsequently, the most feasible pathway is the C–Cl and O–N bonds cleavage along with the N–Cl bond formation of b (b
1
, b
2
) leading to product P
1
CH2O + ClNO, which can further dissociate to give P
5
CH2O + Cl + NO. The second competitive pathway is the 1,3-H-shift associated with O–N bond rupture of b
1
to form P
2
CHClO + HNO. Because the intermediates and transition states involved in the above two favorable channels all lie below the
reactants, the CH2Cl+NO2 reaction is expected to be rapid, as is confirmed by experiment. The present results can lead us to understand deeply the
mechanism of the title reaction and may be helpful for further experimental investigation of the reaction. 相似文献
5.
The ortho-metalated complex [Pd(x){κ
2
(C,N)-[C6H4CH2NRR′ (Y)}] (2a–4a and 2b–3b) was prepared by refluxing in benzene equimolecular amounts of Pd(OAc)2 and secondary benzylamine [a, EtNHCH2Ph; b, t-BuNHCH2Ph followed by addition of excess NaCl. The reaction of the complexes [Pd(x){κ
2
(C,N)-[C6H4CH2NRR′ (Y)}] (2a–4a and 2b–3b) with a stoichiometric amount of Ph3P=C(H)COC6H4-4-Z (Z = Br, Ph) (ZBPPY) (1:1 molar ratio), in THF at low temperature, gives the cationic derivatives [Pd(OC(Z-4-C6H4C=CHPPh3){κ
2
(C,N)-[C6H4CH2NRR′(Y)}] (5a–9a, 4b–6b, and 4b′–6b′), in which the ylide ligand is O-coordinated to the Pd(II) center and trans to the ortho-metalated C(6)H(4) group, in an “end-on
carbonyl”. Ortho-metallation, ylide O-coordination, and C-coordination in complexes (5a–9a, 4b–6b, and 4b′–6b′) were characterized by elemental analysis as well as various spectroscopic techniques. 相似文献
6.
Xiaojun Tan Weihua Wang Ping Li Xiuli Yang Gengxiu Zheng Yuxiang Ma Zhuangdong Yuan 《Theoretical chemistry accounts》2007,118(2):357-362
The formations of the phosphinidene derivative HPNaF and its insertion reactions with R–H (R=F, OH, NH2, CH3) have been systematically investigated employing the density functional theory (DFT), such as the B3LYP and MPW1PW91 methods.
A comparison with the results of MP2 calculations shows that MPW1PW91 underestimates the barrier heights for the four reactions
considered. Similarly, the same is also true for the B3LYP method depending on the selected reactions, but by much less than
MPW1PW91, where the barrier heights of the four reactions are 25.2, 85.7, 119.0, and 142.4 kJ/mol at the B3LYP/6-311+G* level
of theory, respectively. All the mechanisms of the four reactions are identical to each other, i.e., an intermediate has been
located during the insertion reaction. Then, the intermediate could dissociate to substituted phosphinidane(H2RP) and NaF with a barrier corresponding to their respective dissociation energies. Correspondingly, the reaction energies
for the four reactions are −92.2, −68.1, −57.2, and −44.3 kJ/mol at the B3LYP/6-311+G* level of theory, respectively, where
both the B3LYP and MPW1PW91 methods underestimate the reaction energies compared with the MP2 results. The linear correlations
between the calculated barrier heights and the reaction energies have also been observed. As a result, the relative reactivity
among the four insertion reactions should be as follows: H–F > H–OH > H–NH2 > H–CH3. 相似文献
7.
In the present work we investigated a novel triplet ground-state germylenoid HB=GeLiF as well as its insertion reactions with RH(R = F,OH and NH2) using the DFT B3LYP and QCISD methods for the first time.Geometry optimization calculations show that the triplet HB=GeLiF has three equilibrium structures,in which the four-membered ring structure is the most stable with the lowest energy.All mechanisms of the three insertion reactions of germylenoid HB=GeLiF with RH(R = F,OH,and NH2) are identical to each other.Based on the calculated results,it is concluded that under the same conditions the insertion reactions should occur easily in the order of H-F > H-OH > H-NH2.In THF solvent the insertion reactions get more difficult than in the gas phase. 相似文献
8.
Weihua Wang Ping Li Xiaojun Tan Qiufen Wang Gengxiu Zheng Yuxiang Bu 《Structural chemistry》2008,19(3):527-533
The geometries and isomerization of the imine silylenoid HN=SiNaF as well as its insertion reactions with some R–H molecules
have been systematically investigated theoretically, where R=F, OH, NH2, and CH3, respectively. The barrier heights for the four insertion reactions are 67.7, 115.6, 153.5, and 271.5 kJ/mol at the B3LYP/6-311+G*
level of theory, respectively. Here, all the mechanisms of the four reactions are identical to each other, i.e., a stable
intermediate has been formed during the insertion reaction. Then, the intermediate could dissociate into the substituted silylene
(HN=SiHR) and NaF with a barrier corresponding to their respective dissociation energies. Correspondingly, the reaction energies
for the four reactions are 71.8, 95.5, 123.3, and 207.6 kJ/mol, respectively, which are linearly correlated with the calculated
barrier heights. Furthermore, the effects of halogen substitutions (F, Cl, and Br) on the reaction activity have also been
discussed. As a result, the relative reactivity among the four insertion reactions should be as follows: H–F > H–OH > H–NH2 > H–CH3. 相似文献
9.
G. B. Andreev M. Yu. Antipin N. A. Budantseva E. V. Tuchina L. B. Serezhkina A. M. Fedoseev A. B. Yusov 《Russian Journal of Coordination Chemistry》2004,30(12):868-873
A complex of uranyl perchlorate with imidazolidine-2-one as the molecular ligand, [UO2(Imon)4(H2O)](ClO4)2 (I), was synthesized and structurally characterized by X-ray diffraction analysis. The coordination number of the uranium atom is 7. The nearest environment of the uranyl ion includes four O atoms of the imidazolidine-2-one molecules and one O atom of the water molecule. The perchlorate anions are outer-sphere ligands. The crystals are monoclinic: space group P21/c; a = 16.294(3) Å, b = 16.135(3) Å, c = 9.987(2) Å, = 97.69 (3)°, V = 2603.0 (9) Å3, (calcd) = 2.117 g/cm3, Z = 4. The IR and luminescence spectra of the complex were recorded.Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 919–924.Original Russian Text Copyright © 2004 by Andreev, Antipin, Budantseva, Tuchina, Serezhkina, Fedoseev, Yusov. 相似文献
10.
Naomi Masuda Yatsuhisa Nagano T. Kimura 《Journal of Thermal Analysis and Calorimetry》2005,81(3):533-535
Summary The standard molar enthalpy of formation of methyl methylthiomethyl sulfoxide, CH3(CH3SCH2)SO, at T=298.15 K in the liquid state was determined to be -199.4±1.5 kJ mol-1 by means of oxygen rotating-bomb combustion calorimetry. 相似文献
11.
Two new heteropolyoxovanadoborates (H2dap)2H6{(VO)12O6[B3O6(OH)]6(H2O)}·13H2O (1, dap = 1,2-diaminopropane) and {[Zn(dien)]2[Zn(dien)(H2O)]4(VO)12O6[B3O6(OH)]6(H2O)}2·15H2O (2, dien = diethylenetriamine) have been hydrothermally synthesized and structurally characterized. Both 1 and 2 contain {(VO)12O6[B3O6(OH)]6(H2O)} cluster (denoted on V12B18), which is constructed by a puckered B18O36(OH)6 ring sandwiched between two triangles of six alternating cis and trans edge-sharing vanadium atoms, and a central water molecule. 1 consists of discrete [V12B18]10− cluster anions with H2dap2+ as counterions, while 2 consists of discrete neutral {[Zn(dien)]2[Zn(dien)(H2O)]4[V12B18]} clusters, which are built from two types of zinc(II) complex fragments connecting with V12B18 cluster through two Zn-(μ
3-O)-B bonds. Interestingly, 2 is the only example of the V12B18 cluster decorated by two types of zinc(II) complex fragments. 相似文献
12.
S. Hayami T. Kawahara Y. Maeda K. Inoue O. Sato 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(3):521-525
Summary Iron(III) spin-crossover complexes [Fe(pap)2]ClO4. H2O (1), [Fe(pap)2]BF4. H2O (2), [Fe(pap)2]PF6. CH3OH (3), [Fe(CH3-pap)2]ClO4. H2O (4), [Fe0.5Al0.5(pap)2]ClO4. CH3OH (5) and [Fe0.25Al0.75(pap)2] ClO4. CH3OH (6)were prepared andthe spin transition behaviors of the complexes have been studied from magnetic susceptibility and M?ssbauer
spectroscopy measurements. The magnetic properties of light-induced metastable state are measured using Hg-Xe light source.
T1/2is temperature at which the populations of the high-spin and low-spin species are fifty-fifty. Metastable HS is produced by
light irradiation at 5 K. T(LIESST) is the temperature at which the populations of the metastable high-spin species decrease to one half and cooperativity
factor Cis defined as the parameter which presents the strength of cooperativity. The value of T(LIESST) decreases as T1/2increases and the plots of T(LIESST) vs. Cshow linear correlation. The effect of cooperativity of the complexes on the relaxations in solid was confirmed for the iron(III)
complexes. 相似文献
13.
E. G. Tarakanova G. V. Yukhnevich I. S. Kislina V. D. Maiorov 《Journal of Structural Chemistry》2017,58(1):69-77
IR spectroscopic and quantum chemical methods are used to study the competition between water and methanol molecules in the formation of the simplest stable proton disolvates and their subsequent solvation in the case of solutions of KOH in CH3OH and CH3OK in H2O with similar stoichiometries (~1:3-3.5). The complexes found in these solutions are analysed to determine their composition and structure: they are found to be heteroions (CH3O?H?OH)– solvated by two similar solvent molecules. In both cases, there are virtually no complexes of the second possible type (CH3OH·(CH3O?H?OCH3)–··H2O or CH3OH·(HO?H?OH)–·H2O), which appears to be due to the stoichiometric compositions of the solutions. It is shown that a DFT calculation (B3LYP/6-31++G(d,p)) of linear complexes with strong (~15-30 kcal/mol) H bonds reproduces, with good accuracy, the IR spectra of the solutions, which consist mainly of these complexes. 相似文献
14.
Rajeev K. Sinha Edith Nicol Vincent Steinmetz Philippe Maître 《Journal of the American Society for Mass Spectrometry》2010,21(5):758-772
Gas-phase infrared photodissociation spectroscopy is reported for the microsolvated [Mn(ClO4)(H2O)
n
]+ and [Mn2(ClO4)3(H2O)
n
]+ complexes from n = 2 to 5. Electrosprayed ions are isolated in an ion-trap where they are photodissociated. The 2600–3800 cm−1 spectral region associated with the OH stretching mode is scanned with a relatively low-power infrared table-top laser, which
is used in combination with a CO2 laser to enhance the photofragmentation yield of these strongly bound ions. Hydrogen bonding is evidenced by a relatively
broad band red-shifted from the free OH region. Band assignment based on quantum chemical calculations suggest that there
is formation of water—perchlorate hydrogen bond within the first coordination shell of high-spin Mn(II). Although the observed
spectral features are also compatible with the formation of structures with double-acceptor water in the second shell, these
structures are found relatively high in energy compared with structures with all water directly bound to manganese. Using
the highly intense IR beam of the free electron laser CLIO in the 800–1700 cm−1, we were also able to characterize the coordination mode (η2) of perchlorate for two clusters. The comparison of experimental and calculated spectra suggests that the perchlorate Cl—O
stretches are unexpectedly underestimated at the B3LYP level, while they are correctly described at the MP2 level allowing
for spectral assignment. 相似文献
15.
D. A. Loginov A. A. Pronin L. S. Shul’pina E. V. Mutseneck Z. A. Starikova P. V. Petrovskii A. R. Kudinov 《Russian Chemical Bulletin》2008,57(3):546-551
The mononuclear arene complexes [Cb*Co(arene)]+ (3a–g; Cb* = C4Me4; arene is biphenyl (a), diphenylmethane (b), 1,2-diphenylethane (c), diphenyl ether (d), p-terphenyl (e), 1,2-dimesitylethane (f), or 1,3-dimesitylpropane (g)) were synthesized by the reactions of arenes either with the benzene complex [Cb*Co(C6H6)]+ (1) under visible light irradiation or with the acetonitrile derivative [Cb*Co(MeCN)3]+ (2) in refluxing THF. The reactions of 2 with 1,2-diphenyle-thane, 1,3-dimesitylpropane, and p-terphenyl in a ratio of 2: 1 afforded the dinuclear complexes [Cb*Co(μ-η:η-arene)CoCb*]2+ (4c,e,g). The stability of the dinuclear arene complexes was estimated by DFT calculations. The structures of the complexes [3a]PF6 and [3e]PF6 ere established by X-ray diffraction.
For Part 6, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 535–539, March, 2008. 相似文献
16.
Summary. The reaction of [RuCp(CH3CN)3]PF6 with 1 equiv of N-Me-imidazole results in the quantitative formation of [RuCp(1N-N-Me-imidazole)(CH3CN)2]PF6 (1) featuring a 1N rather than a 1C bound N-Me-imidazole ligand. According to DFT/B3LYP calculations, 1N coordination of N-Me-imidazole is preferred over 1C coordination by 25.5kJ/mol. Upon exposure to air 1 reacts with oxygen and water to afford the novel hydroxo-bridged dinuclear complex of [Ru2Cp2(1N-N-Me-imidazole)2(-OH)2](PF6)2 (2) featuring a metal-metal single bond. The dimeric nature of 2 was confirmed by a single-crystal X-ray structure analysis. 相似文献
17.
The hydrogen-bonded structures of the CH3OH complexes with CF4, C2F2, OC, Ne, and He are designated as the starting points for geometry optimizations without and with counterpoise (CP) correction
at MP2 level of theory with the basis sets 6-31+G*, 6-31++G**, and 6-311++G**, respectively. Tight convergence criteria are
applied throughout all geometry optimizations in order to reduce the computational errors. According to the optimizations
without CP correction, a blue-shifted O–H···Y (where Y = F, O, Ne, or He) hydrogen bond exists in all these five complexes.
The magnitudes of blue shifts of ν(O–H) of the former four complexes with respect to that of CH3OH are reduced greatly when the polarization and diffuse functions of the hydrogen atoms are added (results from 6-31+G* versus
those from 6-31++G**). However, for the complexes CH3OH–CF4 and CH3OH–C2F2, our optimizations using the CP corrections did not find the hydrogen-bonded structure to be a stationary point. The energy
minimum of both the complexes corresponds to a non-hydrogen-bonded structure. 相似文献
18.
Nikolay A. Pushkarevsky Sergey N. Konchenko Manfred Scheer 《Journal of Cluster Science》2007,18(3):606-617
The reaction of K2[Fe3(μ3-Q)(CO)9] (Q = Se (K2[1a]), Te (K2[1b])) with [(dppm)PtCl2] leads to the addition of a [(dppm)Pt]2+ unit to a Fe2Q face of the initial cluster. By this way new heteronuclear clusters [Fe3Pt(μ3-Q)(CO)9(dppm)] were obtained possessing a butterfly-shaped cluster core bridged by a μ4-Q unit. It has been found that the resulting Fe-Pt clusters exist as equilibrium mixtures of two isomeric forms in solution
differing by the dppm coordination mode: as a chelate ligand coordinated to Pt or as a bridging ligand coordinated to Pt and
Fe atoms. The mixtures of isomers can be separated by chromatography and the pure isomers can be isolated as stable crystalline
phases. Solutions of both isomers attain equilibrium at normal conditions in about 1 month as found by NMR.
Dedicated to Professor Dieter Fenske in the occasion of his 65th birthday. 相似文献
19.
S. P. Gubin L. G. Kuz'mina A. V. Churakov J. A. K. Howard L. A. Polyakova N. A. Kataeva I. F. Golovaneva A. P. Klyagina 《Russian Chemical Bulletin》2005,54(8):1813-1818
The reaction of the carbidocarbonyl cluster [Fe6C(CO)16]2− with ruthenium(IV) hydroxochloride Ru(OH)Cl3 was studied. At 90–100 °C, the reaction gave products of replacement of Fe atoms by Ru in the [Fe6C(CO)16]2− cluster along with degradation products. Treatment of the replacement products with FeCl3 afforded the [Fe2.96Ru3.04C(CO)17] compound (1), which was characterized by X-ray diffraction analysis. The crystals of cluster 1 are composed of two types of octahedral molecules (1a and 1b) in a ratio of 2 : 1. Molecules 1a are in general positions, and molecules 1b are located on twofold axes. In both molecules, the Fe and Ru atoms are disordered over four of six positions.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1761–1766, August, 2005. 相似文献
20.
L. P. Ogorodova I. A. Kiseleva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(9):1489-1491
A thermochemical study of natural talc was performed by high-temperature melt dissolution calorimetry on a Tian-Calvet calorimeter.
Based on the total values of the increment in enthalpy upon heating the sample from room temperature to 973 K, and of the
dissolution enthalpy at 973 K measured in this work for talc and gibbsite (along with those determined for tremolite, brucite,
and their corresponding oxides), the enthalpy of formation was calculated for talc composed of elements, Mg3[Si4O10](OH)2, at 298.15 K: Δf
H
elo(298.15 K) = −5900.6 ± 4.7 kJ/mol. 相似文献