Complexes Pairing Hypohalous Acids with Nitrosyl Hydride. Blue Shift of a NH Bond That Is Uninvolved in a H-Bond

Correlated calculations are used to analyze the interaction between nitrosyl hydride (HNO) and hypohalous acids (HOF, HOCl, and HOBr). Two minima are located on the potential energy surface of each complex, in both of which HOX acts as proton donor. Donation to the N atom of HNO makes for a more strongly bound complex, as compared to the OH··O bond in the secondary minimum. Binding energies of the global minimum are about 22 kJ/mol, as compared to 18 kJ/mol for the secondary structure; there is little sensitivity to the identity of the halogen atom. Whereas the covalent OH bond of HOX stretches and shifts to the red upon complexation, the NH bond of HNO, whether involved in a H-bond or not, behaves in the opposite manner

Competition between Nonclassical Hydrogen-Bonded Acceptor Sites in Complexes of Neutral AH₂ Radicals (A = B, Al, and Ga): A Theoretical Investigation

An ab initio computational study of the properties of the neutral AH2 radicals (A = B, Al, Ga) as hydrogen-bond (HB) acceptors, with H−X (X = F, Cl, Br, CN, and CCH) as HB donors, is carried out at the UMP2/6-311++G(2d,2p) level. Two different minima have been found for each of the 15 possible dimers. One structure corresponds to a single-electron hydrogen-bonded complex (SEHB), with the A atom acting as an HB acceptor. The second corresponds to a dihydrogen bond complex between one of the hydrogen atoms of AH2 and the H−X molecule. Thus, all the atoms of the neutral AH2 molecule can act as HB acceptors and none as donors. The stability of the SEHB complexes decreases as BH2 > AlH2 > GaH2, while for the dihydrogen-bonded complexes the order is AlH2 > GaH2 > BH2. For the BH2 radical the SEHB complexes are stronger than the dihydrogen bonded ones, while the opposite is found for the AlH2 and GaH2 systems. Regarding the HB donors, the order found for the binding energy in the two types of complexes is H2A···HF > H2A···HCl > H2A···HBr > H2A···HCN > H2A···HCCH

Cooperative and Diminutive Unusual Weak Bonding In F₃CX···HMgH···Y and F₃CX···Y···HMgH Trimers (X = Cl, Br; Y = HCN, and HNC)

MP2 calculations with cc-pVTZ basis set were used to analyze intermolecular interactions in F3CX···HMgH···Y and F3CX···Y···HMgH triads (X = Cl, Br; Y = HCN, and HNC) which are connecting with three kinds of unusual weak interactions, namely halogen−hydride, dihydrogen, and σ-hole. To understand the properties of the systems better, the corresponding dyads are also studied. Molecular geometries, binding energies, and infrared spectra of monomers, dyads, and triads were investigated at the MP2/cc-pVTZ computational level. Particular attention is given to parameters such as cooperative energies, cooperative dipole moments, and many-body interaction energies. Those complexes with simultaneous presence of a σ-hole bond and a dihydrogen bond show cooperativity energy ranging between −1.02 and −2.31 kJ mol−1, whereas those with a halogen−hydride bond and a dihydrogen bond are diminutive, with this energetic effect between 0.1 and 0.63 kJ mol−1. The electronic properties of the complexes have been analyzed using the molecular electrostatic potential (MEP), the electron density shift maps, and the parameters derived from the atoms in molecules (AIM) methodology

A Computational Study of the Potential Energy Surface of Peroxyformic Acid Dimers

MP2 and M05-2x calculations with aug-cc-pVDZ basis sets were used to analyze intermolecular interactions in peroxyformic acid dimers. A total of 18 and 16 minima were located on the potential energy surface of HOOCHO dimer complexes at M05-2x and MP2 computational levels, respectively. The BSSE corrected interaction energies are in a range between 9 and 34 kJ mol−1 at the MP2/aug-cc-pVDZ computational level. The atoms-in-molecules (AIM) theory was also applied to explain the nature of the complexes. The interaction energies have been partitioned with the natural energy decomposition analysis (NEDA) showing that the most important attractive term corresponds to the charge transfer

Single Electron Pnicogen Bonded Complexes

A theoretical study of the complexes formed by monosubstituted phosphines (XH₂P) and the methyl radical (CH₃) has been carried out by means of MP2 and CCSD­(T) computational methods. Two minima configurations have been obtained for each XH₂P:CH₃ complex. The first one shows small P–C distances and, in general, large interaction energies. It is the most stable one except in the case of the H₃P:CH₃ complex. The second minimum where the P–C distance is large and resembles a typical weak pnicogen bond interaction shows interaction energies between −9.8 and −3.7 kJ mol^–1. A charge transfer from the unpaired electron of the methyl radical to the P–X σ* orbital is responsible for the interaction in the second minima complexes. The transition state (TS) structures that connect the two minima for each XH₂P:CH₃ complex have been localized and characterized

Weakly Bound Complexes of N₂O: An ab Initio Theoretical Analysis Toward the Design of N₂O Receptors

Ab initio calculations at MP2/6-311++G(2d,2p) and MP2/6-311++G(3df,3pd) computational levels have been used to analyze the interactions between nitrous oxide and a series of small and large molecules that act simultaneously as hydrogen bond donors and electron donors. The basis set superposition error (BSSE) and zero point energy (ZPE) corrected binding energies of small N2O complexes (H2O, NH3, HOOH, HOO•, HONH2, HCO2H, H2CO, HCONH2, H2CNH, HC(NH)NH2, SH2, H2CS, HCSOH, HCSNH2) vary between −0.93 and −2.90 kcal/mol at MP2/6-311++G(3df,3pd) level, and for eight large complexes of N2O they vary between −2.98 and −3.37 kcal/mol at the MP2/6-311++G(2d,2p) level. The most strongly bound among small N2O complexes (HCSNH2−N2O) contains a NH··N bond, along with S → N interactions, and the most unstable (H2S−N2O) contains just S → N interactions. The electron density properties have been analyzed within the atoms in molecules (AIM) methodology. Results of the present study open a window into the nature of the interactions between N2O with other molecular moieties and open the possibility to design N2O abiotic receptors

Increasing the cell voltage of a magnesium ion battery with B₂₄O₂₄ anode through encapsulating halides: a DFT study

DFT calculations at the GGA/PBE/DNP computational level; were performed to determine the potential application of B24O24 nanocage as the anode of magnesium-ion batteries (MIBs). The calculated results indicate that the pristine B24O24 nanocage is a possible anode material with a voltage of 4.45 V. We also found that the encapsulated halides F–, Cl– and Br– within the B24O24 nanocage can increase the voltage to 7.63, 7.53, and 7.51 V, respectively. These values are compared to previous reports in the literature. The present study results may provide a new perspective for the design of boron-oxygen-based anode nanostructures for MIBs.</p

Symmetric bifurcated halogen bonds: substituent and cooperative effects

<p>The aim of this study is to investigate the geometries, interaction energies and bonding properties of the symmetrical bifurcated halogen bond interactions (BXBs) by means of <i>ab initio</i> calculations. For this purpose, the NCX (X = Cl, Br) molecule is paired with a series of N-formyl formamide (NFF) derivatives (NFF-Z, Z = H, CN, CCH, OH, CH₃ and Li), and the properties of the resulting complexes are studied by molecular electrostatic potential, quantum theory of atoms in molecules, noncovalent interaction index and natural bond orbital analyses. For a fixed NCX molecule, interaction energies increase in the order of Z = Li > CH₃ > H > OH > CCH > CN. We found a strong correlation between the interaction energies of NCX:NFF-Z complexes and molecular electrostatic potential minimum values associated with NFF-Z monomers. Moreover, cooperative effects between BXB and XċċċN halogen bond interactions are studied in the ternary NCX:NCX:NFF-Z systems. Our results indicate that the strength of BXB interactions in the ternary complexes is enhanced by the presence of XċċċN bonds. Besides, cooperativity effects tend to increase the covalency of BXBs in these systems.</p

Theoretical Study of the 1:1 Complexes between Carbon Monoxide and Hypohalous Acids

A theoretical study of the complexes formed between carbon monoxide, CO, and the hypohalous acids (HOX, X = F, Cl, Br, and I) has been carried out using DFT [M05-2x/6-311++G(2d,2p)] and ab initio methods [(MP2/6-311++G(2d,2p) and MP2/aug-cc-pVTZ)]. Six minima were found, which correspond to two hydrogen-bonded complexes, two halogen-bonded complexes, and two van der Waals complexes. The hydrogen-bonded complexes with the carbon atom of the CO molecule are the most stable for hypohalous acids with X = F, Cl, and Br, whereas for X = I, the halogen-bonded complex with the same atom of carbon monoxide is the most stable. A blue shift in the stretching frequency of the OH bond in the hydrogen-bonded complexes with the carbon atom of CO was observed. In addition, a blue shift was observed in the bond of the hypohalous acid not involved in the interaction

Competition of Hydrogen Bonds and Halogen Bonds in Complexes of Hypohalous Acids with Nitrogenated Bases

A theoretical study of the complexes formed by hypohalous acids (HOX, X = F, Cl, Br, I, and At) with three nitrogenated bases (NH3, N2, and NCH) has been carried out by means of ab initio methods, up to MP2/aug-cc-pVTZ computational method. In general, two minima complexes are found, one with an OH···N hydrogen bond and the other one with a X···N halogen bond. While the first one is more stable for the smallest halogen derivatives, the two complexes present similar stabilities for the iodine case and the halogen-bonded structure is the most stable one for the hypoastatous acid complexes