A novel definition for the hydrogen bond is recommended here. It takes into account theoretical and experimental knowledge acquired over past century. This insists on some evidence. Six criteria are listed that could be used as evidence presence of a bond.

Ab initio calculations are used to analyze the CH···O interaction between FnH3-nCH as proton donor and H2O, CH3OH, H2CO acceptor. The is quite weak with CH4 but enhanced by 1 kcal/mol each F added donor. behaves very much like a conventional OH···O H-bond in most respects, including shifts electron density that accompany formation of bond magnitudes various components energy. two sorts H-bonds also gravitate toward similar equilibrium geometry comparably sensitive deformations from...

The term “hydrogen bond” has been used in the literature for nearly a century now. While its importance realized by physicists, chemists, biologists, and material scientists, there continual debate about what this means. This intensified following some important experimental results, especially last decade, which questioned basis of traditional view on hydrogen bonding. Most among them are direct evidence partial covalent nature observation blue-shift stretching frequency X – H···Y bond...

Electronic structure and bonding in metal phthalocyanines (Metal=Fe, Co, Ni, Cu, Zn, Mg) is investigated detail using a density functional method. The atoms are strongly bound to the phthalocyanine ring each case, by as much 10 eV. calculated orbital energy levels relative total energies of these D4h structures indicate that Fe Co have A2g3 Eg2 ground states, respectively, but states changed upon interaction with strong-field axial ligands. valence electronic differ significantly from those...

Among a wide range of noncovalent interactions, hydrogen (H) bonds are well known for their specific roles in various chemical and biological phenomena. When describing conventional bonding, researchers use the notation AH···D (where A refers to electron acceptor D donor). However, AH molecule engaged H-bond can also be pivoted around by roughly 180°, resulting HA···D arrangement. Even without H atom bridging position, this arrangement attractive, as explained Account. The density donated...

Abstract This recommendation proposes a definition for the term “chalcogen bond”; it is recommended used to designate specific subset of inter- and intramolecular interactions formed by chalcogen atoms wherein Group 16 element electrophilic site.

A systematic theoretical study of the electronic structure and bonding in metal meso-tetraphenyl porphines MTPP, M=Fe, Co, Ni, Cu, Zn has been carried out using a density functional theory method. The calculations provide clear elucidation ground states for MTPPs series [MTPP]x ions (x=2+, 1+, 1−, 2−, 3−, 4−), which aids understanding number observed properties. calculation supports experimental assignment unligated FeTPP as A2g3, arises from configuration (dxy)2(dz2)2(dxz)1(dyz)1....

Abstract The characteristics of the pnicogen bond are explored using a variety quantum chemical techniques. In particular, this interaction is compared with its halogen and chalcogen cousins, as well more common H‐bond. general, these bonds all comparable strength. More specifically, they strengthened by presence an electronegative substituent on electron‐acceptor atom, each gains strength one moves down appropriate column periodic table, for example, from N to P As. These noncovalent owe...

Complexes were formed pairing FX, FHY, FH2Z, and FH3T (X = Cl, Br, I; Y S, Se, Te; Z P, As, Sb; T Si, Ge, Sn) with NH3 in order to form an A⋯N noncovalent bond, where A refers the central atom. Geometries, energetics, atomic charges, spectroscopic characteristics of these complexes evaluated via DFT calculations. In all cases, A–F which is located opposite base responsible for σ-hole on atom, elongates its stretching frequency undergoes a shift red. This varies from 42 175 cm−1 largest...

Tetrel bonds are dependent on modification of electron density and electrostatic potential caused by a substituent.

Abstract This recommendation proposes a definition for the term “pnictogen bond”; pnictogen bond designates subset of attractive interactions between an electrophilic region on atom in molecular entity and nucleophilic another, or same, entity.

Ab initio calculations are used to compare the abilities of aromatic groups Phe, Tyr, Trp, and His amino acids (modeled respectively by benzene, phenol, indole, imidazole) form H-bonds three different types. Strongest all conventional (e.g., OH··O OH··N). forms strongest such H-bond, followed then Trp. Whereas OH··φ bonds formed approach a proton donor π electron cloud above system somewhat weaker, they nonetheless represent an important class stabilizing interactions. The strengths in this...

The OH covalent bond of conventional hydrogen bonds the OH···O type undergoes a lengthening as result complex formation, and stretching frequency shifts to red; same is true many CH···O H-bonds. However, subset H-bonds behave in an opposite fashion, with CH contracting, its shifting blue. Ab initio calculations are performed determine whether two contrasting behaviors can be traced different patterns electron density within or they associated very geometrical perturbations proton donor...

Although the peptide CαH group has historically not been thought to form hydrogen bonds within proteins, ab initio quantum calculations show it be a potent proton donor. Its binding energy water molecule lies in range between 1.9 and 2.5 kcal/mol for nonpolar polar amino acids; bond (H-bond) involving charged lysine residue is even stronger than conventional OH··O interaction. The preferred H-bond lengths are quite uniform, about 3.32 Å. Formation of each interaction results downfield shift...

The relative energies of H and D bonds are due to differences in zero-point vibrational energy (ZPVE). Ab initio calculations used assess the changes this quantity that accompany all possible substitutions protium by deuterium a number complexes. ZPVE bond is lower than neutral dimer trimer water. This difference can be traced one particular mode, which displaces bridging atom away from O···O axis. heavier mass lowers frequency, hence associated with it. situation reverses itself ionic...

Ab initio calculations are used to compare the hydrogen bonding ability of acetylene and ethylene, various derivatives, with analogous properties alkanes. Water is as universal proton acceptor paired HCCH, FCCH, ClCCH, NCH well its mono-, di-, trifluorosubstituted derivatives. With regard hydrocarbons, sp-hybridized forms strongest bond, followed by sp2 then sp3. Halogenation donor strengthens each type particularly when substitution takes place on C involved in bond. sp3-hybridized systems...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheoretical studies of proton transfersSteve ScheinerCite this: Acc. Chem. Res. 1985, 18, 6, 174–180Publication Date (Print):June 1, 1985Publication History Published online1 May 2002Published inissue 1 June 1985https://pubs.acs.org/doi/10.1021/ar00114a003https://doi.org/10.1021/ar00114a003research-articleACS PublicationsRequest reuse permissionsArticle Views417Altmetric-Citations210LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant...

When PH3 is paired with NH3, the two molecules are oriented such that P and N atoms face one another directly, without intermediacy of a H atom. Quantum calculations indicate this attraction due in part to transfer electron density from lone pair atom σ* antibond P–H covalent bond. Unlike H-bond, pertinent hydrogen about 180° away from, instead toward, N, overlaps lobe orbital closest P. In contrast halogen bonds, there no requirement σ-hole positive electrostatic potential on atom, nor it...

The ability of one H-bond in a chain to affect others is assessed by comparing the CH···O bonds (H2CO)n and (HFCO)n OH···O (H2O)n. Both sorts interactions grow stronger, intermolecular distances shorter, as number monomers increases. degree cooperativity generally proportional strength H-bond, although display disproportionately high cooperativity. OH··O similar also with respect electron density loss from bridging hydrogen atom, amount charge transferred proton-acceptor molecule donor....

Whereas CH⋯O H-bonds are usually weaker than interpeptide NH⋯O H-bonds, this is not necessarily the case within proteins. The nominally surprisingly strong, comparable to, and in some cases stronger than, context of forces that hold together adjacent strands protein β-sheets. peptide NH greatly weakened as proton donor certain conformations backbone, particularly extended structures, forms correspondingly H-bonds. PH group a weak donor, but will form PH⋯N However, there interaction which P...

Previous work has documented the ability of P atom to form a direct attractive noncovalent interaction with N atom, based in large measure on charge transfer from lone pair into σ* antibonding orbital P-H that is turned away atom. As systems studied date include only hydrides, present considers how substituents affect and examines whether P···N might compete other forces such as H-bonds. It found addition electron-withdrawing greatly strengthens point where it exceeds majority The highest...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProton transfers in hydrogen-bonded systems. Cationic oligomers of waterSteve ScheinerCite this: J. Am. Chem. Soc. 1981, 103, 2, 315–320Publication Date (Print):January 1, 1981Publication History Published online1 May 2002Published inissue 1 January 1981https://pubs.acs.org/doi/10.1021/ja00392a012https://doi.org/10.1021/ja00392a012research-articleACS PublicationsRequest reuse permissionsArticle Views290Altmetric-Citations145LEARN ABOUT THESE...