共查询到20条相似文献,搜索用时 15 毫秒
1.
Dr. Meng Gao Xin Yang Prof. Dr. Jianbo Cheng Qingzhong Li Wenzuo Li Prof. Dr. Robert E. Loffredo 《Chemphyschem》2013,14(14):3341-3347
The ternary systems of C2H4 (C2H2 or C6H6)‐MCN‐HF (M=Cu, Ag, Au) and the respective binary systems were investigated to study the interplay between metal???π interactions and hydrogen bonds. The metal???π interactions in C2H4‐MCN become stronger with the irregular order Ag<Cu<Au, while the hydrogen bonds in MCN‐HF become weaker following the same order. The metal???π interactions are weakened as the H atoms in the π system are replaced with electron‐withdrawing groups and enhanced by electron‐donating groups. Type 1 of these ternary systems, in which MCN acts as Lewis base and acid simultaneously, is more stable than type 2, in which C2H4 acts as a double Lewis base. Negative cooperativity is present in type 2 ternary systems with a weakening of the metal???π interactions and the hydrogen bonds. Positive cooperativity is found in type 1 ternary systems with an enhancement of the metal???π interactions and the hydrogen bonds, except for C2(CN)4‐AuCN‐HF‐1. The weaker metal???π interaction in C6H6‐AuCN has a greater enhancing effect on the hydrogen bond in AuCN‐HF than those in C2H4‐AuCN and C2H2‐AuCN. These synergetic effects were analyzed with the natural bond orbital and energy decomposition. 相似文献
2.
Behavior of Halogen Bonds of the Y−X⋅⋅⋅π Type (X,Y=F,Cl, Br,I) in the Benzene π System,Elucidated by Using a Quantum Theory of Atoms in Molecules Dual‐Functional Analysis 下载免费PDF全文
The nature of halogen bonds of the Y?X‐?‐π(C6H6) type (X, Y=F, Cl, Br, and I) have been elucidated by using the quantum theory of atoms in molecules (QTAIM) dual‐functional analysis (QTAIM‐DFA), which we proposed recently. Asterisks (?) emphasize the presence of bond‐critical points (BCPs) in the interactions in question. Total electron energy densities, Hb( r c), are plotted versus Hb( r c)?Vb( r c)/2 [=(?2/8m)?2ρb( r c)] for the interactions in QTAIM‐DFA, in which Vb( r c) are potential energy densities at the BCPs. Data for perturbed structures around fully optimized structures were used for the plots, in addition to those of the fully optimized ones. The plots were analyzed by using the polar (R, θ) coordinate for the data of fully optimized structures with (θp, κp) for those that contained the perturbed structures; θp corresponds to the tangent line of the plot and κp is the curvature. Whereas (R, θ) corresponds to the static nature, (θp, κp) represents the dynamic nature of the interactions. All interactions in Y?X‐?‐π(C6H6) are classified by pure closed‐shell interactions and characterized to have vdW nature, except for Y?I‐?‐π(C6H6) (Y=F, Cl, Br) and F?Br‐?‐π(C6H6), which have typical hydrogen‐bond nature without covalency. I?I‐?‐π(C6H6) has a borderline nature between the two. Y?F‐?‐π(C6H6) (Y=Br, I) were optimized as bent forms, in which Y‐?‐π interactions were detected. The Y‐?‐π interactions in the bent forms are predicted to be substantially weaker than those in the linear F?Y‐?‐π(C6H6) forms. 相似文献
3.
Deshuang Tu Hong Yan Jordi Poater Miquel Sol 《Angewandte Chemie (International ed. in English)》2020,59(23):9018-9025
Non‐covalent interactions involving multicenter multielectron skeletons such as boron clusters are rare. Now, a non‐covalent interaction, the nido‐cage???π bond, is discovered based on the boron cluster C2B9H12? and an aromatic π system. The X‐ray diffraction studies indicate that the nido‐cage???π bonding presents parallel‐displaced or T‐shaped geometries. The contacting distance between cage and π ring varies with the type and the substituent of the aromatic ring. Theoretical calculations reveal that this nido‐cage???π bond shares a similar nature to the conventional anion???π or π???π bonds found in classical aromatic ring systems. This nido‐cage???π interaction induces variable photophysical properties such as aggregation‐induced emission and aggregation‐caused quenching in one molecule. This work offers an overall understanding towards the boron cluster‐based non‐covalent bond and opens a door to investigate its properties. 相似文献
4.
Ran Li Prof. Dr. Qingzhong Li Prof. Dr. Jianbo Cheng Zhenbo Liu Prof. Dr. Wenzuo Li 《Chemphyschem》2011,12(12):2289-2295
We designed M1???C6H5X???HM2 (M1=Li+, Na+; X=Cl, Br; M2=Li, Na, BeH, MgH) complexes to enhance halogen–hydride halogen bonding with a cation–π interaction. The interaction strength has been estimated mainly in terms of the binding distance and the interaction energy. The results show that halogen–hydride halogen bonding is strengthened greatly by a cation–π interaction. The interaction energy in the triads is two to six times as much as that in the dyads. The largest interaction energy is ?8.31 kcal mol?1 for the halogen bond in the Li+???C6H5Br???HNa complex. The nature of the cation, the halogen donor, and the metal hydride influence the nature of the halogen bond. The enhancement effect of Li+ on the halogen bond is larger than that of Na+. The halogen bond in the Cl donor has a greater enhancement than that in the Br one. The metal hydride imposes its effect in the order HBeH<HMgH<HNa<HLi for the Cl complex and HBeH<HMgH<HLi<HNa for the Br complex. The large cooperative energy indicates that there is a strong interplay between the halogen–hydride halogen bonding and the cation–π interaction. Natural bond orbital and energy decomposition analyses indicate that the electrostatic interaction plays a dominate role in enhancing halogen bonding by a cation–π interaction. 相似文献
5.
Exploring the (Very Flat) Potential Energy Landscape of R−Br⋅⋅⋅π Interactions with Accurate CCSD(T) and SAPT Techniques
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Dr. Kevin E. Riley Mariela Vazquez Cole Umemura Christopher Miller Khanh‐An Tran 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(49):17690-17695
Halogen bonds involving an aromatic moiety as an acceptor, otherwise known as R?X???π interactions, have increasingly been recognized as being important in materials and in protein–ligand complexes. These types of interactions have been the subject of many recent investigations, but little is known about the ways in which the strengths of R?X???π interactions vary as a function of the relative geometries of the interacting pairs. Here we use the accurate CCSD(T) and SAPT2+3δMP2 methods to investigate the potential energy landscapes for systems of HBr, HCCBr, and NCBr complexed with benzene. It is found that only the separation between the complexed molecules have a strong effect on interaction strength while other geometric parameters, such as tilting and shifting R?Br???π donor relative to the benzene plane, affect these interactions only mildly. Importantly, it is found that the C6v (T‐shaped) configuration is not the global minimum for any of the dimers investigated. 相似文献
6.
Qingzhong Li Dr. Qingquan Lin Wenzuo Li Jianbo Cheng Baoan Gong Jiazhong Sun 《Chemphyschem》2008,9(15):2265-2269
Ab initio calculations are used to provide information on H3N???XY???HF triads (X, Y=F, Cl, Br) each having a halogen bond and a hydrogen bond. The investigated triads include H3N???Br2‐HF, H3N???Cl2???HF, H3N???BrCI???HF, H3N???BrF???HF, and H3N???ClF???HF. To understand the properties of the systems better, the corresponding dyads are also investigated. Molecular geometries, binding energies, and infrared spectra of monomers, dyads, and triads are studied at the MP2 level of theory with the 6‐311++G(d,p) basis set. Because the primary aim of this study is to examine cooperative effects, particular attention is given to parameters such as cooperative energies, many‐body interaction energies, and cooperativity factors. The cooperative energy ranges from ?1.45 to ?4.64 kcal mol?1, the three‐body interaction energy from ?2.17 to ?6.71 kcal mol?1, and the cooperativity factor from 1.27 to 4.35. These results indicate significant cooperativity between the halogen and hydrogen bonds in these complexes. This cooperativity is much greater than that between hydrogen bonds. The effect of a halogen bond on a hydrogen bond is more pronounced than that of a hydrogen bond on a halogen bond. 相似文献
7.
Prof. Yanli Zeng Dr. Xueying Zhang Dr. Xiaoyan Li Prof. Lingpeng Meng Prof. Shijun Zheng 《Chemphyschem》2011,12(6):1080-1087
The halogen bonding of furan???XY and thiophene???XY (X=Cl, Br; Y=F, Cl, Br), involving σ‐ and π‐type interactions, was studied by using MP2 calculations and quantum theory of “atoms in molecules” (QTAIM) studies. The negative electrostatic potentials of furan and thiophene, as well as the most positive electrostatic potential (VS,max) on the surface of the interacting X atom determined the geometries of the complexes. Linear relationships were found between interaction energy and VS,max of the X atom, indicating that electrostatic interactions play an important role in these halogen‐bonding interactions. The halogen‐bonding interactions in furan???XY and thiophene???XY are weak, “closed‐shell” noncovalent interactions. The linear relationship of topological properties, energy properties, and the integration of interatomic surfaces versus VS,max of atom X demonstrate the importance of the positive σ hole, as reflected by the computed VS,max of atom X, in determining the topological properties of the halogen bonds. 相似文献
8.
The intermolecular interactions in C6H6???LiX (X=OH, NH2, F, Cl, Br, NC, CN) complexes are investigated by using second‐order Møller–Plesset perturbation theory (MP2) calculations and quantum theory of “atoms in molecules” (QTAIM) studies, and the role of π electrons is studied in the formation of these benzene‐containing lithium‐bonded complexes. The molecular electrostatic potentials of benzene and LiX determine the geometries of the lithium‐bonded complexes. The electron densities at the lithium bond critical points in the πC6H6???LiX complexes are obviously stronger than those in the σC6H6???LiX complexes, which indicates that the intermolecular interactions in the C6H6???LiX complexes are mainly attributable to π‐type interaction. The topological and energy properties at the lithium bond critical points in both the C6H6???LiX and πC6H6???LiX complexes are linear with the interaction energies, thereby showing the crucial role of the π electrons in the formation of these complexes. Electron localization function (ELF) analysis indicates that the formation of the lithium bonds leads to the reduction of the ELF π‐electron density and volume, and the reduction of the π‐electron volume is linear with the interaction energies with the correction coefficient 0.9949. 相似文献
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Juan Forniés Violeta Sicilia Pilar Borja José M. Casas Alvaro Díez Elena Lalinde Carmen Larraz Antonio Martín M. Teresa Moreno 《化学:亚洲杂志》2012,7(12):2813-2823
The neutral compounds [Pt(bzq)(CN)(CNR)] (R=tBu ( 1 ), Xyl ( 2 ), 2‐Np ( 3 ); bzq= benzoquinolate, Xyl=2,6‐dimethylphenyl, 2‐Np=2‐napthyl) were isolated as the pure isomers with a trans‐Cbzq,CNR configuration, as confirmed by 13C{1H} NMR spectroscopy in the isotopically marked [Pt(bzq)(13CN)(CNR)] (R=tBu ( 1′ ), Xyl ( 2′ ), 2‐Np ( 3′ )) derivatives (δ13CCN≈110 ppm; 1J(Pt,13C)≈1425 Hz]. By contrast, complex [Pt(bzq)(C≡CPh)(CNXyl)] ( 4 ) with a trans‐Nbzq,CNR configuration, has been selectively isolated from [Pt(bzq)Cl(CNXyl)] (trans‐Nbzq,CNR) using Sonogashira conditions. X‐ray diffraction studies reveal that while 1 adopts a columnar‐stacked chain structure with Pt–Pt distances of 3.371(1) Å and significant π???π interactions (3.262 Å), complex 2 forms dimers supported only by short Pt???Pt (3.370(1) Å) interactions. In complex 4 the packing is directed by weak bzq???Xyl and bzq???C≡E (C, N) interactions. In solid state at room temperature, compounds 1 and 2 both show a bright red emission (?=42.1 % 1 , 57.6 % 2 ). Luminescence properties in the solid state at 77 K and concentration‐dependent emission studies in CH2Cl2 at 298 K and at 77 K are also reported for 1 , 1·CHCl3 , 2 , 2' , 2·CHCl3 , 3 , 4 . 相似文献
11.
The effect of different donor nitrogen atoms on the strength and nature of intramolecular Se ??? N interactions is evaluated for organoselenium compounds having N,N‐dimethylaminomethyl (dime), oxazoline (oxa) and pyridyl (py) substituents. Quantum chemical calculations on three series of compounds [2‐(dime)C6H4SeX ( 1 a – g ), 2‐(oxa)C6H4SeX ( 2 a – g ), 2‐(py)C6H4SeX ( 3 a – g ); X=Cl, Br, OH, CN, SPh, SePh, CH3] at the B3LYP/6‐31G(d) level show that the stability of different conformers depends on the strength of intramolecular nonbonded Se ??? N interactions. Natural bond orbital (NBO), NBO deletion and atoms in molecules (AIM) analyses suggest that the nature of the Se ??? N interaction is predominantly covalent and involves nN→σ*Se? X orbital interaction. In the three series of compounds, the strength of the Se ??? N interaction decreases in the order 3 > 2 > 1 for a particular X, and it decreases in the order Cl>Br>OH>SPh≈CN≈SePh>CH3 for all the three series 1 – 3 . However, further analyses suggest that the differences in strength of Se ??? N interaction in 1 – 3 is predominantly determined by the distance between the Se and N atoms, which in turn is an outcome of specific structures of 1 , 2 and 3 , and the nature of the donor nitrogen atoms involved has very little effect on the strength of Se ??? N interaction. It is also observed that Se ??? N interaction becomes stronger in polar solvents such as CHCl3, as indicated by the shorter rSe ??? N and higher ESe ??? N values in CHCl3 compared to those observed in the gas phase. 相似文献
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Holger Kruse Klaudia Mrazikova Luigi D'Ascenzo Jiri Sponer Pascal Auffinger 《Angewandte Chemie (International ed. in English)》2020,59(38):16553-16560
Current interest in lone‐pair???π (lp???π) interactions is gaining momentum in biochemistry and (supramolecular) chemistry. However, the physicochemical origin of the exceptionally short (ca. 2.8 Å) oxygen‐to‐nucleobase plane distances observed in prototypical Z‐DNA CpG steps remains unclear. High‐level quantum mechanical calculations, including SAPT2+3 interaction energy decompositions, demonstrate that lp???π contacts do not result from n→π* orbital overlaps but from weak dispersion and electrostatic interactions combined with stereochemical effects imposed by the locally strained structural context. They also suggest that the carbon van der Waals (vdW) radii, originally derived for sp3 carbons, should not be used for smaller sp2 carbons attached to electron‐withdrawing groups. Using a more adapted carbon vdW radius results in these lp???π contacts being no longer of the sub‐vdW type. These findings challenge the whole lp???π concept that refers to elusive orbital interactions that fail to explain short interatomic contact distances. 相似文献
15.
Resonance Character of Copper/Silver/Gold Bonding in Small Molecule⋅⋅⋅MX (X=F,Cl, Br,CH3, CF3) Complexes 下载免费PDF全文
Prof. Guiqiu Zhang Huanjing Yue Dr. Frank Weinhold Hui Wang Hong Li Dezhan Chen 《Chemphyschem》2015,16(11):2424-2431
The resonance character of Cu/Ag/Au bonding is investigated in B???M?X (M=Cu, Ag, Au; X=F, Cl, Br, CH3, CF3; B=CO, H2O, H2S, C2H2, C2H4) complexes. The natural bond orbital/natural resonance theory results strongly support the general resonance‐type three‐center/four‐electron (3c/4e) picture of Cu/Ag/Au bonding, B:M?X?B+?M:X?, which mainly arises from hyperconjugation interactions. On the basis of such resonance‐type bonding mechanisms, the ligand effects in the more strongly bound OC???M?X series are analyzed, and distinct competition between CO and the axial ligand X is observed. This competitive bonding picture directly explains why CO in OC???Au?CF3 can be readily replaced by a number of other ligands. Additionally, conservation of the bond order indicates that the idealized relationship bB???M+bMX=1 should be suitably generalized for intermolecular bonding, especially if there is additional partial multiple bonding at one end of the 3c/4e hyperbonded triad. 相似文献
16.
Influence of the Homopolar Dihydrogen Bonding CH⋅⋅⋅HC on Coordination Geometry: Experimental and Theoretical Studies 下载免费PDF全文
Dr. Damir A. Safin Dr. Maria G. Babashkina Dr. Koen Robeyns Dr. Mariusz P. Mitoraj Dr. Piotr Kubisiak Prof. Yann Garcia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16679-16687
The reaction of the N‐thiophosphorylated thiourea (HOCH2)(Me)2CNHC(S)NHP(S)(OiPr)2 (HL), deprotonated by the thiophosphorylamide group, with NiCl2 leads to green needles of the pseudotetrahedral complex [Ni(L‐1,5‐S,S′)2] ? 0.5 (n‐C6H14) or pale green blocks of the trans square‐planar complex trans‐[Ni(L‐1,5‐S,S′)2]. The former complex is stabilized by homopolar dihydrogen C?H???H?C interactions formed by n‐hexane solvent molecules with the [Ni(L‐1,5‐S,S′)2] unit. Furthermore, the dispersion‐dominated C?H??? H?C interactions are, together with other noncovalent interactions (C?H???N, C?H???Ni, C?H???S), responsible for pseudotetrahedral coordination around the NiII center in [Ni(L ‐1,5‐S,S′)2] ? 0.5 (n‐C6H14). 相似文献
17.
John N. Low Justo Cobo Manuel Nogueras Adolfo Snchez Harlen Torres Braulio Insuasty 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):o298-o300
The supramolecular structure of the title compound, C19H15N3, is defined by π–π‐stacking and C—H?π interactions. There are no conventional hydrogen bonds in the structure. 相似文献
18.
C. John McAdam Brian H. Robinson Jim Simpson 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(7):m338-m340
In the title compound, [Ni(C5H5)(C5H7O)(C18H15P)], the molecule adopts the expected half‐sandwich structure with no unusual metal–ligand distances. No classical hydrogen bonds are found in the structure; instead, the OH group of the butynol unit is involved in an unusual O—H...π interaction with the C[triple‐bond]C group of an adjacent molecule. The crystal structure is further stabilized by C—H...O and C—H...π interactions, leading to an extensive network of spiral columns. 相似文献
19.
《International journal of quantum chemistry》2018,118(8)
The intermolecular π‐hole···π‐electrons interactions between F2ZO (Z = C, Si, Ge) molecules and unsaturated hydrocarbons including acetylene, ethylene, 1,3‐butadiene and benzene were constructed to reveal the differences of tetrel bonds forming by carbon and heavier tetrel atoms. The ab initio computation in association with topological analysis of electron density, natural bond orbital, and energy decomposition analysis demonstrate that the strength of Si···π and Ge···π tetrel bonds is much stronger than that of C···π tetrel bonds. The Si···π and Ge···π tetrel bonds exhibit covalent or partially covalent interaction nature, while the weak C···π tetrel bonds display the hallmarks of noncovalent interaction, the electrostatic interaction is the primary influencing factor. The Si···π and Ge···π interactions are determined by both the σ‐ and π‐electron densities, while the C···π interactions are dominated mainly by the π‐electron densities. The π‐hole···π‐electrons tetrel bonds are dominated by electrostatic interaction, and polarization has a comparable contribution in the Si···π and Ge···π tetrel bonds. 相似文献
20.
Probing the CH⋅⋅⋅π Weak Hydrogen Bond in Anesthetic Binding: The Sevoflurane–Benzene Cluster 下载免费PDF全文
Nathan A. Seifert Dr. Daniel P. Zaleski Dr. Cristóbal Pérez Dr. Justin L. Neill Prof. Brooks H. Pate Montserrat Vallejo‐López Prof. Alberto Lesarri Dr. Emilio J. Cocinero Prof. Fernando Castaño Prof. Isabelle Kleiner 《Angewandte Chemie (International ed. in English)》2014,53(12):3210-3213
Cooperativity between weak hydrogen bonds can be revealed in molecular clusters isolated in the gas phase. Here we examine the structure, internal dynamics, and origin of the weak intermolecular forces between sevoflurane and a benzene molecule, using multi‐isotopic broadband rotational spectra. This heterodimer is held together by a primary C? H???π hydrogen bond, assisted by multiple weak C? H???F interactions. The multiple nonbonding forces hinder the internal rotation of benzene around the isopropyl C? H bond in sevoflurane, producing detectable quantum tunneling effects in the rotational spectrum. 相似文献