We report here the calculations on electronic structures of mono- and bi-nuclear benzene - transition metal sandwich complexes by means of CNDO/2 program, on the basis of molecular orbital components, atomic net charg...We report here the calculations on electronic structures of mono- and bi-nuclear benzene - transition metal sandwich complexes by means of CNDO/2 program, on the basis of molecular orbital components, atomic net charges and bond orders, the bonding pictures are analysed and discussed.展开更多
Carbon dioxide as a notorious greenhouse gas triggers severe global warming which is threatening the balance of ecosystem. In this respect, effectively capturing and transforming CO_(2)into value-added chemicals are e...Carbon dioxide as a notorious greenhouse gas triggers severe global warming which is threatening the balance of ecosystem. In this respect, effectively capturing and transforming CO_(2)into value-added chemicals are essential but still challenging tasks. As a kind of emerging crystalline porous material, covalent organic frameworks(COFs) have been demonstrated to be able to adsorb gases and function as catalysts to facilitate chemical transformations. Herein, we report an imine-linked, cobalt sandwich complex-based COF(Co-BD-COF) with high crystallinity and large surface area.Co-BD-COF can efficiently catalyze the transformation of CO_(2)into cyclic carbonates due to abundant metal sites and high porosity. In addition, Co-BD-COF exhibits high catalytic selectivity toward small ethylene oxide derivatives in cycloaddition reaction due to the large steric hindrance around the cobalt complexes rendered by the peripheral phenyl moieties.This new metal sandwich-type building block provides a new strategy for improving catalytic selectivity of COFs.展开更多
A supramolecular inclusion complex between β-cyclodextrin（β-CD） and α-naphthylacetic acid was prepared, and its crystal structure was investigated by single-crystal X-ray crystallography. The complex contains two...A supramolecular inclusion complex between β-cyclodextrin（β-CD） and α-naphthylacetic acid was prepared, and its crystal structure was investigated by single-crystal X-ray crystallography. The complex contains two β-CD molecules, one α-naphthylacetic acid, two ethanols and twenty-eight water molecules in the asymmetric unit, which could be formulated as [（C42H70O35）2·（C12H10O2）·（C2H5OH）2·28H2O]. Two β-CD molecules constitute a dimer by face-to-face contact of their secondary hydroxyl sides. At the interface of the dimer, one α-naphthylacetic acid molecule is sandwiched between two β-CD molecules. Each β-CD unit of the dimer includes one ethanol molecule in its cavity. The β-CD dimers are linked together via hydrogen bonding to form layers that are stacked in a brickwork-like pattern. The comparative study of some sandwich complexes elucidates that the interface of the β-CD dimer has a stronger inclusion capacity than the cavity of β-CD for some suitable planar guest molecules. The novel inclusion structure results from the competitive inclusion of α-naphthylacetic acid and ethanol.展开更多
The reaction of the 16e half-sandwich complex Cp*Co(S2C2B10H10) (1) (Cp* = pentamethylcyclopentadienyl) with excess methyl acetylene monocarboxylate, HC≡C-CO2Me, affords the 18e complexes 2-6. Compound 2 bears a B-CH...The reaction of the 16e half-sandwich complex Cp*Co(S2C2B10H10) (1) (Cp* = pentamethylcyclopentadienyl) with excess methyl acetylene monocarboxylate, HC≡C-CO2Me, affords the 18e complexes 2-6. Compound 2 bears a B-CH2 unit in which B-substitution occurs in the B(3)/B(6) position of the ortho-carborane cage. Complexes 3-6 are geometrical isomers, in which the alkyne is twofold inserted into one of the Co-S bonds in all the four possible ways. Treatment of 1 with excess 3-butyn-2-one or phenyl ethynyl ketone, HC≡C-C(O)R (R = Me, Ph), at ambient temperature leads to the 18e complexes 7-10, respectively, with two alkynes inserted into one of the Co-S bonds. All the new complexes were fully characterized by spectroscopic techniques and elemental analysis. The solid-state structures of 2, 3, 5, 7, 8, 9 and 10 were further characterized by X-ray structural analysis.展开更多
In this paper the electronic configurations of n+1-decker transition metal sandwich com-plexes have been generally discussed by means of the structural rule of transition metalheterocarborans and the numbers of their ...In this paper the electronic configurations of n+1-decker transition metal sandwich com-plexes have been generally discussed by means of the structural rule of transition metalheterocarborans and the numbers of their valence bonding orbitals have been obtained as fol-lows: VBO = 6n + 3-6n + 5,which are not dependent on the properties of transition metal atoms and coordination rings.Then the results of EHMO quantum chemistry calculations of the model skeletons and cor-responding analyses on electronic configurations of actual molecules for double-, triple- andtetra-decker sandwich complexes have been discussed to verify the above formula.展开更多
A density functional theory and wave function theory investigation on the possibility of carbon-free phosphametallocenes [P3MP3]2-and arsenametallocenes [As3MAs3]2- (M=Ni, Pd, Pt) is presented in this work. Staggered ...A density functional theory and wave function theory investigation on the possibility of carbon-free phosphametallocenes [P3MP3]2-and arsenametallocenes [As3MAs3]2- (M=Ni, Pd, Pt) is presented in this work. Staggered singlet D3d [E3ME3]2- (E=P, As)-the smallest inorganic metallocenes possible to construct-proved to be the global minima of the heptaatomic sys- tems and may be targeted in future experiments. Cyclo-P3- and cyclo-As3- turned out to possess similar aromaticity to cyclo-P5- and cyclo-As5- and may serve as effective ligands to sandwich a wide range of transition metals. The first vertical electron detachment energies of Cs [E3ME3]Li+ monoanions with a staggered [E3ME3]2- sandwich core were predicted to be between 2.7 and 2.9 eV; the extent of stabilization by Li+ suggests that such materials be viable targets for experimental characterization.展开更多
The nonlinear vibration fundamental equation of circular sandwich plate under uniformed load and circumjacent load and the loosely clamped boundary condi- tion were established by von Karman plate theory, and then acc...The nonlinear vibration fundamental equation of circular sandwich plate under uniformed load and circumjacent load and the loosely clamped boundary condi- tion were established by von Karman plate theory, and then accordingly exact solution of static load and its numerical results were given. Based on time mode hypothesis and the variational method, the control equation of the space mode was derived, and then the amplitude frequency-load character relation of circular sandwich plate was obtained by the modified iteration method. Consequently the rule of the effect of the two kinds of load on the vibration character of the circular sandwich plate was investigated. When circumjacent load makes the lowest natural frequency zero, critical load is obtained.展开更多
Treatment of 1,3-di- t -butylcyclopentadiene with rhodium trichloride in EtOH leads to the formation of binuclear half-sandwich complex [Cp t RhCl( μ -Cl)] 2 (1) (Cp t = η 5- t Bu 2C 5H 3) which reacts with trimethy...Treatment of 1,3-di- t -butylcyclopentadiene with rhodium trichloride in EtOH leads to the formation of binuclear half-sandwich complex [Cp t RhCl( μ -Cl)] 2 (1) (Cp t = η 5- t Bu 2C 5H 3) which reacts with trimethylphosphine to give Cp t Rh(PMe 3)Cl 2(2) in high yield. 2 reacts with ammonium polysulfide, (NH 4) 2S x to give cyclooligosulfido half-sandwich complexes Cp t Rh(PMe 3)(S n )( n =4(4a),6(4b)). Desulfurization of 4b by excess PPh 3 results in cyclotetrasulfido product 4a, while 4a takes up sulfur from polysulfide to convert cyclohexasulfido product 4b. The reaction of 2 with Et 4NI gives diiodide complex 3 which is determined by single crystal X-ray crystallographic analysis.展开更多
Due to a viscoelastic damping middle layer,sandwich structures have the capacity of energy consumption.In this paper,we describe the frequency-dependent property of viscoelastic materials using complex modulus model,a...Due to a viscoelastic damping middle layer,sandwich structures have the capacity of energy consumption.In this paper,we describe the frequency-dependent property of viscoelastic materials using complex modulus model,and iterative modal strain energy method and iterative complex eigenvalue method are presented to obtain frequency and loss factor of sandwich structures.The two methods are effective and exact for the large-scale complex composite sandwich structures.Then an optimum analysis method is suggested to apply to sandwich structures.Finally,as an example,an optimum analysis of a clamped-clamped sandwich beams is conducted,theoretical closed-form solution and numerical predictions are studied comparatively,and the results agree well.展开更多
The reaction of \[Cp\+\%t\%RhCl\-2\]\-2(1) (Cp\+\%t\%=η\+5\|\{\}\+\%t\%Bu\-2C\-5\|H\-3) with 1,2\|dilithium dichalcogenolate carborane Li\-2E\-2C\-2B\-\{10\}H\-\{10\}(E=S, Se) afforded the 16\|electron rhodium(Ⅲ) ha...The reaction of \[Cp\+\%t\%RhCl\-2\]\-2(1) (Cp\+\%t\%=η\+5\|\{\}\+\%t\%Bu\-2C\-5\|H\-3) with 1,2\|dilithium dichalcogenolate carborane Li\-2E\-2C\-2B\-\{10\}H\-\{10\}(E=S, Se) afforded the 16\|electron rhodium(Ⅲ) half\|sandwich complexes \{Cp\+\%t\%Rh(E\-2C\-2B\-\{10\}H\-\{10\})\}\3a), Se(3b)\]. 18\|Electron trimethyl phosphine rhodium(Ⅲ) half\|sandwich complexes Cp\+\%t\%Rh(PMe\-3)(E\-2C\-2B\-\{10\}H\-\{10\})\. 18\|Electron trimethyl phosphine rhodium(Ⅲ) half\|sandwich complexes Cp\+\%t\%Rh(PMe\-3)(E\-2C\-2B\-\{10\}H\-\{10\})\4a), Se(4b), Te(4c)\] can be synthesized both by addition of PMe\-3 into 16\|electron complexes can be synthesized both by addition of PMe\-3 into 16\|electron complexes 3a, 3b and by the reaction Cp\+\%t\%Rh(PMe\-3)Cl\-2(2) with Li\-2E\-2C\-2B\-\{10\}H\-\{10\}(\{E=S\}, Se, Te). The molecular geometry of 4b was determined by X\|ray diffraction structural analysis.展开更多
文摘We report here the calculations on electronic structures of mono- and bi-nuclear benzene - transition metal sandwich complexes by means of CNDO/2 program, on the basis of molecular orbital components, atomic net charges and bond orders, the bonding pictures are analysed and discussed.
基金supported by the National Natural Science Foundation of China (51973153 and 21704065)the National Key Research and Development Program of China (2017YFA0207500)+1 种基金Guangdong Basic and Applied Basic Research Foundation (2021A1515010228)the Innovation Research Foundation of Shenzhen (JCYJ20190808115215125)。
文摘Carbon dioxide as a notorious greenhouse gas triggers severe global warming which is threatening the balance of ecosystem. In this respect, effectively capturing and transforming CO_(2)into value-added chemicals are essential but still challenging tasks. As a kind of emerging crystalline porous material, covalent organic frameworks(COFs) have been demonstrated to be able to adsorb gases and function as catalysts to facilitate chemical transformations. Herein, we report an imine-linked, cobalt sandwich complex-based COF(Co-BD-COF) with high crystallinity and large surface area.Co-BD-COF can efficiently catalyze the transformation of CO_(2)into cyclic carbonates due to abundant metal sites and high porosity. In addition, Co-BD-COF exhibits high catalytic selectivity toward small ethylene oxide derivatives in cycloaddition reaction due to the large steric hindrance around the cobalt complexes rendered by the peripheral phenyl moieties.This new metal sandwich-type building block provides a new strategy for improving catalytic selectivity of COFs.
基金Supported by the Natural Science Foundation of Hainan Province, China(No.808145)the Doctoral Foundation of Hainan Normal University, China(No.103303)the Key Discipline of Hainan Province Organic Chemistry, China(No.006).
文摘A supramolecular inclusion complex between β-cyclodextrin（β-CD） and α-naphthylacetic acid was prepared, and its crystal structure was investigated by single-crystal X-ray crystallography. The complex contains two β-CD molecules, one α-naphthylacetic acid, two ethanols and twenty-eight water molecules in the asymmetric unit, which could be formulated as [（C42H70O35）2·（C12H10O2）·（C2H5OH）2·28H2O]. Two β-CD molecules constitute a dimer by face-to-face contact of their secondary hydroxyl sides. At the interface of the dimer, one α-naphthylacetic acid molecule is sandwiched between two β-CD molecules. Each β-CD unit of the dimer includes one ethanol molecule in its cavity. The β-CD dimers are linked together via hydrogen bonding to form layers that are stacked in a brickwork-like pattern. The comparative study of some sandwich complexes elucidates that the interface of the β-CD dimer has a stronger inclusion capacity than the cavity of β-CD for some suitable planar guest molecules. The novel inclusion structure results from the competitive inclusion of α-naphthylacetic acid and ethanol.
基金the National Natural Science Foundation of China (20925104,90713023,20771055,20721002)the Major State Basic Research Development Program of China (2006CB806104)the National Basic Research Program of China (2007CB925101,2010CB923303)
文摘The reaction of the 16e half-sandwich complex Cp*Co(S2C2B10H10) (1) (Cp* = pentamethylcyclopentadienyl) with excess methyl acetylene monocarboxylate, HC≡C-CO2Me, affords the 18e complexes 2-6. Compound 2 bears a B-CH2 unit in which B-substitution occurs in the B(3)/B(6) position of the ortho-carborane cage. Complexes 3-6 are geometrical isomers, in which the alkyne is twofold inserted into one of the Co-S bonds in all the four possible ways. Treatment of 1 with excess 3-butyn-2-one or phenyl ethynyl ketone, HC≡C-C(O)R (R = Me, Ph), at ambient temperature leads to the 18e complexes 7-10, respectively, with two alkynes inserted into one of the Co-S bonds. All the new complexes were fully characterized by spectroscopic techniques and elemental analysis. The solid-state structures of 2, 3, 5, 7, 8, 9 and 10 were further characterized by X-ray structural analysis.
基金the National Natural Science Foundation of China.
文摘In this paper the electronic configurations of n+1-decker transition metal sandwich com-plexes have been generally discussed by means of the structural rule of transition metalheterocarborans and the numbers of their valence bonding orbitals have been obtained as fol-lows: VBO = 6n + 3-6n + 5,which are not dependent on the properties of transition metal atoms and coordination rings.Then the results of EHMO quantum chemistry calculations of the model skeletons and cor-responding analyses on electronic configurations of actual molecules for double-, triple- andtetra-decker sandwich complexes have been discussed to verify the above formula.
基金supported by the National Natural Science Foundation of China (Grant No. 20873117)
文摘A density functional theory and wave function theory investigation on the possibility of carbon-free phosphametallocenes [P3MP3]2-and arsenametallocenes [As3MAs3]2- (M=Ni, Pd, Pt) is presented in this work. Staggered singlet D3d [E3ME3]2- (E=P, As)-the smallest inorganic metallocenes possible to construct-proved to be the global minima of the heptaatomic sys- tems and may be targeted in future experiments. Cyclo-P3- and cyclo-As3- turned out to possess similar aromaticity to cyclo-P5- and cyclo-As5- and may serve as effective ligands to sandwich a wide range of transition metals. The first vertical electron detachment energies of Cs [E3ME3]Li+ monoanions with a staggered [E3ME3]2- sandwich core were predicted to be between 2.7 and 2.9 eV; the extent of stabilization by Li+ suggests that such materials be viable targets for experimental characterization.
文摘The nonlinear vibration fundamental equation of circular sandwich plate under uniformed load and circumjacent load and the loosely clamped boundary condi- tion were established by von Karman plate theory, and then accordingly exact solution of static load and its numerical results were given. Based on time mode hypothesis and the variational method, the control equation of the space mode was derived, and then the amplitude frequency-load character relation of circular sandwich plate was obtained by the modified iteration method. Consequently the rule of the effect of the two kinds of load on the vibration character of the circular sandwich plate was investigated. When circumjacent load makes the lowest natural frequency zero, critical load is obtained.
基金Financial support by the National Natural Science Foundation of China and by the Special Funds for Major State Basic Research Projects(G1999064800)is gratefully acknowledged.
文摘Treatment of 1,3-di- t -butylcyclopentadiene with rhodium trichloride in EtOH leads to the formation of binuclear half-sandwich complex [Cp t RhCl( μ -Cl)] 2 (1) (Cp t = η 5- t Bu 2C 5H 3) which reacts with trimethylphosphine to give Cp t Rh(PMe 3)Cl 2(2) in high yield. 2 reacts with ammonium polysulfide, (NH 4) 2S x to give cyclooligosulfido half-sandwich complexes Cp t Rh(PMe 3)(S n )( n =4(4a),6(4b)). Desulfurization of 4b by excess PPh 3 results in cyclotetrasulfido product 4a, while 4a takes up sulfur from polysulfide to convert cyclohexasulfido product 4b. The reaction of 2 with Et 4NI gives diiodide complex 3 which is determined by single crystal X-ray crystallographic analysis.
文摘Due to a viscoelastic damping middle layer,sandwich structures have the capacity of energy consumption.In this paper,we describe the frequency-dependent property of viscoelastic materials using complex modulus model,and iterative modal strain energy method and iterative complex eigenvalue method are presented to obtain frequency and loss factor of sandwich structures.The two methods are effective and exact for the large-scale complex composite sandwich structures.Then an optimum analysis method is suggested to apply to sandwich structures.Finally,as an example,an optimum analysis of a clamped-clamped sandwich beams is conducted,theoretical closed-form solution and numerical predictions are studied comparatively,and the results agree well.
文摘The reaction of \[Cp\+\%t\%RhCl\-2\]\-2(1) (Cp\+\%t\%=η\+5\|\{\}\+\%t\%Bu\-2C\-5\|H\-3) with 1,2\|dilithium dichalcogenolate carborane Li\-2E\-2C\-2B\-\{10\}H\-\{10\}(E=S, Se) afforded the 16\|electron rhodium(Ⅲ) half\|sandwich complexes \{Cp\+\%t\%Rh(E\-2C\-2B\-\{10\}H\-\{10\})\}\3a), Se(3b)\]. 18\|Electron trimethyl phosphine rhodium(Ⅲ) half\|sandwich complexes Cp\+\%t\%Rh(PMe\-3)(E\-2C\-2B\-\{10\}H\-\{10\})\. 18\|Electron trimethyl phosphine rhodium(Ⅲ) half\|sandwich complexes Cp\+\%t\%Rh(PMe\-3)(E\-2C\-2B\-\{10\}H\-\{10\})\4a), Se(4b), Te(4c)\] can be synthesized both by addition of PMe\-3 into 16\|electron complexes can be synthesized both by addition of PMe\-3 into 16\|electron complexes 3a, 3b and by the reaction Cp\+\%t\%Rh(PMe\-3)Cl\-2(2) with Li\-2E\-2C\-2B\-\{10\}H\-\{10\}(\{E=S\}, Se, Te). The molecular geometry of 4b was determined by X\|ray diffraction structural analysis.
