Showing papers on "Chemical bond published in 2013"
01 Jan 2013
TL;DR: In this article, the authors carried out a natural bond orbital analysis of hydrogen bonding in the water dimer for the near Hartree-Fock wave function of Popkie, Kistenmacher, and Clementi, extending previous studies based on smaller basis sets and less realistic geometry.
Abstract: We have carried out a natural bond orbital analysis of hydrogen bonding in the water dimer for the near‐Hartree–Fock wave function of Popkie, Kistenmacher, and Clementi, extending previous studies based on smaller basis sets and less realistic geometry. We find that interactions which may properly be described as ‘‘charge transfer’’ (particularly the n‐σ*OH interaction along the H‐bond axis) play a critical role in the formation of the hydrogen bond, and without these interactions the water dimer would be 3–5 kcal/mol repulsive at the observed equilibrium distance. We discuss this result in relationship to Klemperer’s general picture of the bonding in van der Waals molecules, and to previous theoretical analyses of hydrogen bonding by the method of Kitaura and Morokuma.
2,043 citations
TL;DR: A tutorial review on covalent adaptable networks (CANs), in which covalently crosslinked networks are formed such that triggerable, reversible chemical structures persist throughout the network, and how the application of a stimulus causes these materials to alter their shape, topography, and properties is provided.
Abstract: Covalently crosslinked materials, classically referred to as thermosets, represent a broad class of elastic materials that readily retain their shape and molecular architecture through covalent bonds that are ubiquitous throughout the network structure. These materials, in particular in their swollen gel state, have been widely used as stimuli responsive materials with their ability to change volume in response to changes in temperature, pH, or other solvent conditions and have also been used in shape memory applications. However, the existence of a permanent, unalterable shape and structure dictated by the covalently crosslinked structure has dramatically limited their abilities in this and many other areas. These materials are not generally reconfigurable, recyclable, reprocessable, and have limited ability to alter permanently their stress state, topography, topology, or structure. Recently, a new paradigm has been explored in crosslinked polymers – that of covalent adaptable networks (CANs) in which covalently crosslinked networks are formed such that triggerable, reversible chemical structures persist throughout the network. These reversible covalent bonds can be triggered through molecular triggers, light or other incident radiation, or temperature changes. Upon application of this stimulus, rather than causing a temporary shape change, the CAN structure responds by permanently adjusting its structure through either reversible addition/condensation or through reversible bond exchange mechanisms, either of which allow the material to essentially reequilibrate to its new state and condition. Here, we provide a tutorial review on these materials and their responsiveness to applied stimuli. In particular, we review the broad classification of these materials, the nature of the chemical bonds that enable the adaptable structure, how the properties of these materials depend on the reversible structure, and how the application of a stimulus causes these materials to alter their shape, topography, and properties.
748 citations
TL;DR: These experiments establish that compounds violating chemical intuition can be thermodynamically stable even in simple systems at nonambient conditions.
Abstract: Sodium chloride (NaCl), or rocksalt, is well characterized at ambient pressure. As a result of the large electronegativity difference between Na and Cl atoms, it has highly ionic chemical bonding (with 1:1 stoichiometry dictated by charge balance) and B1-type crystal structure. By combining theoretical predictions and diamond anvil cell experiments, we found that new materials with different stoichiometries emerge at high pressures. Compounds such as Na3Cl, Na2Cl, Na3Cl2, NaCl3, and NaCl7 are theoretically stable and have unusual bonding and electronic properties. To test this prediction, we synthesized cubic and orthorhombic NaCl3 and two-dimensional metallic tetragonal Na3Cl. These experiments establish that compounds violating chemical intuition can be thermodynamically stable even in simple systems at nonambient conditions.
408 citations
TL;DR: A novel definition of bond order is proposed, called the Laplacian bond order (LBO), which is defined as a scaled integral of negative parts of the LaPlacian of electron density in fuzzy overlap space, which has a direct correlation with the bond polarity, the bond dissociation energy, and the bond vibrational frequency.
Abstract: Bond order is an important concept for understanding the nature of a chemical bond. In this work, we propose a novel definition of bond order, called the Laplacian bond order (LBO), which is defined as a scaled integral of negative parts of the Laplacian of electron density in fuzzy overlap space. Many remarkable features of LBO are exemplified by numerous structurally diverse molecules. It is shown that LBO has a direct correlation with the bond polarity, the bond dissociation energy, and the bond vibrational frequency. The dissociation behavior of LBO of the N–N bond in N2 has been studied. Effects of the basis sets, theoretic methods, and geometrical conformations on LBO have also been investigated. Through comparisons, we discussed in details similarities and discrepancies among LBO, Mayer bond order, natural localized molecular orbital bond order, fuzzy overlap population, and electron density at bond critical points.
327 citations
TL;DR: It is suggested that care must be taken when using quantum chemistry to assess metal-ligand covalency in this part of the periodic table and also topological analysis of the electron density via the quantum theory of atoms-in-molecules.
Abstract: A covalent chemical bond carries the connotation of overlap of atomic orbitals between bonded atoms, leading to a buildup of the electron density in the internuclear region. Stabilization of the valence 5f orbitals as the actinide series is crossed leads, in compounds of the minor actinides americium and curium, to their becoming approximately degenerate with the highest occupied ligand levels and hence to the unusual situation in which the resultant valence molecular orbitals have significant contributions from both actinide and the ligand yet in which there is little atomic orbital overlap. In such cases, the traditional quantum-chemical tools for assessing the covalency, e.g., population analysis and spin densities, predict significant metal–ligand covalency, although whether this orbital mixing is really covalency in the generally accepted chemical view is an interesting question. This review discusses our recent analyses of the bonding in AnCp3 and AnCp4 (An = Th–Cm; Cp = η5-C5H5) using both the trad...
266 citations
TL;DR: A review of the optical properties of Mn4+ ions in a number of host lattices is presented in this article, where a simple criterion is proposed, which can effectively and easily describe ionicity/covalency of the Mn4-doped crystals.
243 citations
TL;DR: Recent experimental and theoretical advances of this new class of aromatic borometallic compounds, which contain a highly coordinated central transition metal atom inside a monocyclic boron ring are discussed.
Abstract: Atomic clusters have intermediate properties between that of individual atoms and bulk solids, which provide fertile ground for the discovery of new molecules and novel chemical bonding. In addition, the study of small clusters can help researchers design better nanosystems with specific physical and chemical properties. From recent experimental and computational studies, we know that small boron clusters possess planar structures stabilized by electron delocalization both in the σ and π frameworks. An interesting boron cluster is B9–, which has a D8h molecular wheel structure with a single boron atom in the center of a B8 ring. This ring in the D8h-B9– cluster is connected by eight classical two-center, two-electron bonds. In contrast, the cluster’s central boron atom is bonded to the peripheral ring through three delocalized σ and three delocalized π bonds. This bonding structure gives the molecular wheel double aromaticity and high electronic stability. The unprecedented structure and bonding pattern i...
213 citations
TL;DR: The most important conceptual aspects of the electronic metal-support interaction are described, a phenomenon related to the direct modification of the metal nano-particle determined by the formation of chemical bonds at the interface with the oxide.
Abstract: Understanding the interaction of small metal clusters and isolated atoms with oxide surfaces is crucial in order to rationalize the properties of heterogeneous catalysts composed of sub-nanometer metal particles dispersed on an oxide support. The interaction with the oxide surface can significantly alter the original properties of the metal deposit. In particular, the occurrence and the direction of charge transfer at the metal/oxide interface determine the chemical activity of the supported catalyst. The charge transfer depends on a number of factors like the nature of the oxide (reducible or non-reducible), the surface exposed, the presence of defects, the nature of the supported metal, etc. In this article we describe the most important conceptual aspects of the electronic metal–support interaction, a phenomenon related to the direct modification of the metal nano-particle determined by the formation of chemical bonds at the interface with the oxide. For metal nano-particles with a size of about 1 nm or below these effects become dominant although difficult to identify experimentally.
197 citations
TL;DR: In this paper, a review of recent efforts to describe such bonds accurately and consistently across the s-, p-, and d-blocks is presented, in order to identify broadly applicable methods for inorganic chemistry.
166 citations
TL;DR: First-principles calculations show that, under pressure, caesium atoms can share their 5p electrons to become formally oxidized beyond the +1 state and shows that the inner-shell electrons can become the main components of chemical bonds.
Abstract: The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry, rooted in the atomic shell structure. Within compounds, Group I elements, for example, invariably assume the +1 oxidation state, and their chemical properties differ completely from those of the p-block elements. These general rules govern our understanding of chemical structures and reactions. Here, first-principles calculations show that, under pressure, caesium atoms can share their 5p electrons to become formally oxidized beyond the +1 state. In the presence of fluorine and under pressure, the formation of CsFn (n > 1) compounds containing neutral or ionic molecules is predicted. Their geometry and bonding resemble that of isoelectronic XeFn molecules, showing a caesium atom that behaves chemically like a p-block element under these conditions. The calculated stability of the CsFn compounds shows that the inner-shell electrons can become the main components of chemical bonds. Caesium has so far not been found in oxidation states higher than +1, but quantum chemical calculations have now shown that, under high pressures, 5p inner shell electrons of caesium can participate in — and become the main components of — bonds. Caesium is predicted to form stable CsFn molecules that resemble isoelectronic XeFn.
TL;DR: Calorimetric measurements of metal vapor adsorption energies onto clean oxide surfaces in ultrahigh vacuum show that the chemical potential increases with decreasing particle size below 6 nm, and, for a given size, decreases with the adhesion energy between the metal and its support, Eadh.
Abstract: Many catalysts consist of metal nanoparticles anchored to the surfaces of oxide supports. These are key elements in technologies for the clean production and use of fuels and chemicals. We show here that the chemical reactivity of the surface metal atoms on these nanoparticles is closely related to their chemical potential: the higher their chemical potential, the more strongly they bond to small adsorbates. Controlling their chemical potential by tuning the structural details of the material can thus be used to tune their reactivity. As their chemical potential increases, this also makes the metal surface less noble, effectively pushing its behavior upwards and to the left in the periodic table. Also, when the metal atoms are in a nanoparticle with higher chemical potential, they experience a larger thermodynamic driving force to sinter. Calorimetric measurements of metal vapor adsorption energies onto clean oxide surfaces in ultrahigh vacuum show that the chemical potential increases with decreasing particle size below 6 nm, and, for a given size, decreases with the adhesion energy between the metal and its support, Eadh. The structural factors that control the metal/oxide adhesion energy are thus also keys for tuning catalytic performance. For a given oxide, Eadh increases with (ΔHsub,M − ΔHf,MOx)/ΩM2/3 for the metal, where ΔHsub,M is its heat of sublimation, ΔHf,MOx is the standard heat of formation of that metal's most stable oxide (per mole of metal), and ΩM is the atomic volume of the bulk solid metal. The value ΔHsub,M − ΔHf,MOx equals the heat of formation of that metal's oxide from a gaseous metal atom plus O2(g), so it reflects the strength of the chemical bonds which that metal atom can make to oxygen, and ΩM2/3 simply normalizes this energy to the area per metal atom, since Eadh is the adhesion energy per unit area. For a given metal, Eadh to different clean oxide surfaces increases as: MgO(100) ≈ TiO2(110) ≤ α-Al2O3(0001) < CeO2−x(111) ≤ Fe3O4(111). Oxygen vacancies also increase Eadh, but surface hydroxyl groups appear to decrease Eadh, even though they increase the initial heat of metal adsorption.
TL;DR: The versatility of the SSAdNDP method is demonstrated by applying it to several systems featuring both localized and many-center chemical bonding, and varying in structural complexity: boron α-sheet, magnesium diboride and the Na8BaSn6 Zintl phase.
Abstract: A new tool to elucidate chemical bonding in bulk solids, surfaces and nanostructures has been developed. Solid State Adaptive Natural Density Partitioning (SSAdNDP) is a method to interpret chemical bonding in terms of classical lone pairs and two-center bonds, as well as multi-center delocalized bonds. Here we extend the domain of AdNDP to bulk materials and interfaces, yielding SSAdNDP. We demonstrate the versatility of the method by applying it to several systems featuring both localized and many-center chemical bonding, and varying in structural complexity: boron α-sheet, magnesium diboride and the Na8BaSn6 Zintl phase.
TL;DR: The MOFs adhered well to SPPO via chemical bonds, and yielded the mixed-matrix Fe-MIL-101-NH(2)-SPPO membrane for use in fuel cells.
TL;DR: The results of this study should help in the atomic-scale understanding of the dependence of the reactivity of N-graphene on its microstructure, inspire the study of various types of heteroatom-doped graphenes to improve their catalytic efficiency, and provide a theoretical framework to analyze their reactivities.
Abstract: We report a density functional theory (DFT) study of microscopic detailed effects of the bonding configuration of nitrogen-doped graphene (N-graphene) within the carbon lattice (including pyridinic, pyrrolic, and graphitic N) on the reactivity and mechanistic processes of H2O2 reduction reaction. We simulated the adsorption process of H2O2, analyzed the mechanistic processes, and calculated the reversible potential of each reaction step of the H2O2 reduction reaction on N-graphene. The results indicate that the adsorption of H2O2 on the pristine and N-doped graphene surfaces occurs via physisorption without the formation of a chemical bond. When H+ is introduced into the system, a series of reactions can occur, including the breakage of the O–O bond, the formation of an O–C chemical bond between oxygen and graphene, and the creation of water molecules. The results also indicate a decrease in the energy of the system and a positive reversible potential for each reaction step. The calculations of the relative energy of each reaction step and the value of the onset potential for H2O2 reduction reaction suggest that the reactivity of pristine and N-doped graphene has the following order: pyridinic N-graphene > pyrrolic N-graphene > graphitic N-graphene > pristine graphene. We also proposed an explanation based on electrostatic potential calculations for this dependence of the reactivity order on the bond configuration of the doping in N-graphene. The results of this study should help in the atomic-scale understanding of the dependence of the reactivity of N-graphene on its microstructure, inspire the study of various types of heteroatom-doped graphenes to improve their catalytic efficiency, and provide a theoretical framework to analyze their reactivities.
TL;DR: Based on the recently proposed super valence bond model, the 23c-14e bi-icosahedral Au(23)((+9)) core of Au(38)(SR)(24) is proved to be a superatomic molecule.
Abstract: Based on the recently proposed super valence bond model, in which superatoms can compose superatomic molecules by sharing valence pairs and nuclei for shell closure, the 23c-14e bi-icosahedral Au(23)((+9)) core of Au(38)(SR)(24) is proved to be a superatomic molecule. Molecular orbital analysis reveals that the Au(23)((+9)) core is an exact analogue of the F(2) molecule in electronic configuration. Chemical bonding analysis by the adaptive natural density partitioning method confirms the superatomic molecule bonding framework of Au(38)(SR)(24) in a straightforward manner.
TL;DR: Three additional M-Cr complexes have been isolated, where the iron site is systematically replaced with other first-row transition metals (Mn, Co, or Ni), while the chromium site is kept invariant, characterized by X-ray crystallography.
Abstract: In the field of metal–metal bonding, the occurrence of stable, multiple bonds between different transition metals is uncommon, and is largely unknown for different first-row metals. Adding to a rec...
TL;DR: The results indicate that the rare gas bond is a new kind of weak interaction, like the hydrogen bond for example.
Abstract: At the averaged quadratic coupled-cluster (AQCC) level, a number of selected rare gas (Rg) containing systems have been studied using the quantum theory of atoms in molecules (QTAIM), natural bond orbital (NBO), and several other analysis methods. According to the criteria for a covalent bond, most of the Rg–M (Rg = He, Ne, Ar, Kr, Xe; M = Be, Cu, Ag, Au, Pt) bonds in this study are assigned to weak interactions instead of van der Walls or covalent ones. Our results indicate that the rare gas bond is a new kind of weak interaction, like the hydrogen bond for example.
TL;DR: High-resolution high-angle annular dark-field scanning transmission electron microscopy indicated that the clathrate Ba8Au16P30 is well-ordered on the atomic scale, although numerous twinning and intergrowth defects as well as antiphase boundaries were detected.
Abstract: A novel clathrate phase, Ba8Au16P30, was synthesized from its elements. High-resolution powder X-ray diffraction and transmission electron microscopy were used to establish the crystal structure of the new compound. Ba8Au16P30 crystallizes in an orthorhombic superstructure of clathrate-I featuring a complete separation of gold and phosphorus atoms over different crystallographic positions, similar to the Cu-containing analogue, Ba8Cu16P30. Barium cations are trapped inside the large polyhedral cages of the gold–phosphorus tetrahedral framework. X-ray diffraction indicated that one out of 15 crystallographically independent phosphorus atoms appears to be three-coordinate. Probing the local structure and chemical bonding of phosphorus atoms with 31P solid-state NMR spectroscopy confirmed the three-coordinate nature of one of the phosphorus atomic positions. High-resolution high-angle annular dark-field scanning transmission electron microscopy indicated that the clathrate Ba8Au16P30 is well-ordered on the a...
TL;DR: The basic physics of the measurements, the model that is used for data interpretation, and the ways to extract the bond information from the experimental data are reviewed to help the planning and analysis of single molecule force spectroscopy experiments.
TL;DR: Straightforward access to a cerium(IV)-carbene complex was provided by one-electron oxidation of an anionic "ate" Cerium(III)- carbene precursor, thereby avoiding decomposition reactions that plague oxidations of neutral cerium (III) compounds.
Abstract: Straightforward access to a cerium(IV)-carbene complex was provided by one-electron oxidation of an anionic "ate" cerium(III)-carbene precursor, thereby avoiding decomposition reactions that plague oxidations of neutral cerium(III) compounds. The cerium(IV)-carbene complex is the first lanthanide(IV)-element multiple bond and involves a twofold bonding interaction of two electron pairs between cerium and carbon.
TL;DR: The isolation and structural characterization of a thermally stable compound featuring a Cu-B one-electron bond, as well as its oxidized and reduced (two-electrons-bonded) congeners, provides an excellent opportunity to study the degree of σ-bonding in a metalloboratrane as a function of electron count.
Abstract: Virtually all chemical bonds consist of one or several pairs of electrons shared by two atoms. Examples of σ-bonds made of a single electron delocalized over two neighboring atoms were until recently found only in gas-phase cations such as H_2^+ and Li_2^+ and in highly unstable species generated in solid matrices. Only in the past decade was bona fide one-electron bonding observed for molecules in fluid solution. Here we report the isolation and structural characterization of a thermally stable compound featuring a Cu–B one-electron bond, as well as its oxidized (nonbonded) and reduced (two-electrons-bonded) congeners. This triad provides an excellent opportunity to study the degree of σ-bonding in a metalloboratrane as a function of electron count.
TL;DR: In this article, the structure data on metal-alkoxides, metal alcohol, metal-carboxylates, metal carboxylic acid, metalazolate and metal-azole coordination compounds from the Cambridge Structural Database (CSD) were analyzed in terms of bond lengths.
Abstract: Structure data on metal-alkoxides, metal-alcohol, metal-carboxylates, metal-carboxylic acid, metal-azolate and metal-azole coordination compounds from the Cambridge Structural Database (CSD) were analysed in terms of bond lengths. In general the anionic ligands form shorter metal-ligand bonds by about 0.02-0.05 angstrom compared to neutral ligands, a clear indication of a charge contribution to the bonding interactions. This small difference is not, however, deemed as sufficient to generate two distinct classes of metal-ligand bonding. Instead, the anionic ligands can be viewed as having "charge assisted" metal-ligand bonding, corresponding to the same term used for "charge-assisted hydrogen bonding".
TL;DR: MP2(full)/6-311++G(3df,3pd) calculations were carried out on complexes linked through various non-covalent Lewis acid – Lewis base interactions, finding changes connected with the redistribution of the electron charge being the effect of the complex formation are in line with Bent´s rule.
Abstract: MP2(full)/6-311++G(3df,3pd) calculations were carried out on complexes linked through various non-covalent Lewis acid – Lewis base interactions. These are: hydrogen bond, dihydrogen bond, hydride bond and halogen bond. The quantum theory of ´atoms in molecules´ (QTAIM) as well as the natural bond orbitals (NBO) method were applied to analyze properties of these interactions. It was found that for the A-H…B hydrogen bond as well as for the A-X…B halogen bond (X designates halogen) the complex formation leads to the increase of s-character in the A-atom hybrid orbital aimed toward the H or X atom. In opposite, for the A…H-B hydride bond, where the H-atom possesses negative charge, the decrease of s-character in the B-atom orbital is observed. All these changes connected with the redistribution of the electron charge being the effect of the complex formation are in line with Bent´s rule. The numerous correlations between energetic, geometrical, NBO and QTAIM parameters were also found.
TL;DR: In this article, the electronic structure and interatomic bonding in four major CSH crystalline phases with structures close to those found in hardened Portland cement are investigated via ab initio methods, revealing the critical role of hydrogen bonding and importance of specifying precise locations for water molecules.
TL;DR: In this paper, the authors used near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and first-principle density functional theory to examine chemical bonding and perturbation of the π-electron cloud at graphene-metal interfaces.
Abstract: The nature of chemical bonding at graphene–metal interfaces is intriguing from a fundamental perspective and has great relevance for contacts to novel spintronics and high-frequency electronic devices. Here, we use near-edge X-ray absorption fine structure (NEXAFS) spectroscopy in conjunction with Raman spectroscopy and first-principles density functional theory to examine chemical bonding and perturbation of the π-electron cloud at graphene–metal interfaces. Graphene–metal bonding has been contrasted for graphene interfaced with single-crystalline metals, polycrystalline metal foils, and with evaporated metal overlayers and is seen to be strongest at the last noted interface. Strong covalent metal-d-graphene-π hybridization and hole doping of graphene is observed upon deposition of Ni and Co metal contacts onto graphene/SiO2 and is significantly stronger for these metals in comparison to Cu. Of single-crystalline substrates, the most commensurate (111) facets exhibit the strongest interactions with the graphene lattice. First-principles electronic structure simulations, validated by direct comparison of simulated spectra with NEXAFS measurements, suggest that metal deposition induces a loss of degeneracy between the α- and β-graphene sublattices and that spin-majority and spin-minority channels are distinctly coupled to graphene, contributing to splitting of the characteristic π* resonance. Finally, the electronic structure of graphene is found to be far less perturbed by metal deposition when the π cloud is pinned to an underlying substrate; this remarkable behaviour of “sandwich” structures has been attributed to electronic accessibility of only one face of graphene and illustrates the potential for anisotropic functionalization.
TL;DR: The nature of the intramolecular halogen···halogen bonding studied here appears to be of an unusually strong van der Waals type.
Abstract: By analysing the properties of the electron density in the structurally simple perhalogenated ethanes, X3C–CY3 (X, Y = F, Cl), a previously overlooked non-covalent attraction between halogens attached to opposite carbon atoms is found. Quantum chemical calculations extrapolated towards the full solution of the Schrodinger equation reveal the complex nature of the interaction. When at least one of the halogens is a chlorine, the strength of the interaction is comparable to that of hydrogen bonds. Further analysis shows that the bond character is quite different from standard non-covalent halogen bonds and hydrogen bonds; no bond critical points are found between the halogens, and the σ-holes of the halogens are not utilised for bonding. Thus, the nature of the intramolecular halogen⋯halogen bonding studied here appears to be of an unusually strong van der Waals type.
TL;DR: The ligand-based concept of shortening quintuple bonds and some of its limitations are reported and a chromium-arene sandwich complex structurally related to the classic dibenzene chromium complex was observed, even when bulkier substituents are introduced at the central carbon atom of the used guanidinato ligand.
Abstract: Herein, the ligand-based concept of shortening quintuple bonds and some of its limitations are reported. In dichromium-diguanidinato complexes, the length of the quintuple bond can be influenced by the substituent at the central carbon atom of the used ligand. The guanidinato ligand with a 2,6-dimethylpiperidine backbone was found to be the optimal ligand. The reduction of its chromium(II) chloride-ate complex gave a quintuply bonded bimetallic complex with a CrCr distance of 1.7056 (12)angstrom. Its metal-metal distance, the shortest observed in any stable compound yet, is of essentially the same length as that of the longest alkane CC bond (1.704 (4)angstrom). Both molecules, the alkane and the Cr complex, are of remarkable stability. Furthermore, an unsupported Cr-I dimer with an effective bond order (EBO) of 1.25 between the two metal atoms, indicated by CASSCF/CASPT2 calculations, was isolated as a by-product. The formation of this by-product indicates that with a certain bulk of the guanidinato ligand, other coordination isomers become relevant. Over-reduction takes place, and a chromium-arene sandwich complex structurally related to the classic dibenzene chromium complex was observed, even when bulkier substituents are introduced at the central carbon atom of the used guanidinato ligand.
TL;DR: In this article, the NEDA scheme of the decomposition of the interaction energy was applied to analyze the effect of cooperativity on the formation of the hydrogen and halogen bonds.
Abstract: The cooperativity effects in the Cl−···HCCH···HF, Cl−···ClCCH···HF and F−···ClCCH···HF complexes are analyzed here. The results show that the formation of the hydrogen and halogen bonds is ruled by the same mechanisms and that the cooperativity enhances these interactions. The MP2(full)/6-311 ++G(d,p) calculations were performed for the above triads and the corresponding sub-units; dyads linked by the hydrogen or halogen bonds and monomers. The NEDA scheme of the decomposition of the interaction energy was applied here. It was found that for the halogen bonded systems, the most important is the polarization term of the energy of interaction while for the hydrogen bonds the charge transfer interaction energy and next the electrostatic contribution. The interaction between orbitals is also analyzed here in terms of the Natural Bond Orbitals method.
TL;DR: A charge-displacement analysis of gold-ethyne complexes shows the existence of a quantitative relationship between measurable properties and the chemical bond constituents in the Dewar-Chatt-Duncanson model, and crucial insight into the nature of coordination bonds may be gained.
Abstract: A charge-displacement analysis of gold-ethyne complexes shows the existence of a quantitative relationship between measurable properties and the chemical bond constituents in the Dewar-Chatt-Duncanson model. Through suitable experiments, these constituents may be disentangled and crucial insight into the nature of coordination bonds may thus be gained.