Structural organization and dimensionality at the hands of weak intermolecular Au···Au, Au···X and X···X (X = Cl, Br, I) interactions

The salts K[AuCl(2)(CN)(2)]·H(2)O (1), K[AuBr(2)(CN)(2)]·2H(2)O (2) and K[AuI(2)(CN)(2)]·?H(2)O (3) were synthesized and structurally characterized. Compound 1 crystallizes as a network of square planar [AuCl(2)(CN)(2)](-) anions separated by K(+) cations. However, 2 and 3 feature 2-D sheets built by the aggregation of [AuX(2)(CN)(2)](-) anions via weak, intermolecular X···X interactions. The mixed anion double salts K(3)[Au(CN)(2)](2)[AuBr(2)(CN)(2)]·H(2)O (4) and K(5)[Au(CN)(2)](4)[AuI(2)(CN)(2)]·2H(2)O (5) were also synthesized by cocrystallization of K[Au(CN)(2)] and the respective K[AuX(2)(CN)(2)] salts. Similarly to 2 and 3, the [Au(CN)(2)](-) and [AuX(2)(CN)(2)](-) anions form 2-D sheets via weak, intermolecular Au(I)···X and Au(I)···Au(I) interactions. In the case of 5, a rare unsupported Au(I)···Au(III) interaction of 3.5796(5) ? is also seen between the two anionic units. Despite the presence of Au(I) aurophilic interactions of 3.24-3.45 ?, neither 4 nor 5 exhibit any detectable emission at room temperature, suggesting that the presence of Au(I)···X or Au(I)···Au(III) interactions may affect the emissive properties.     

On the properties of X···N noncovalent interactions for first-, second-, and third-row X atoms

In addition to a structure with a PH···N H-bond, a second complex of greater stability is formed when the PH(3) is rotated such that its P-H bond is pointing away from the approaching N lone pair of NH(3). Quantum calculations are applied to examine whether such a complex is characteristic only of P, or may occur as well for other atoms of the first, second, or third rows of the periodic table. The molecules PH(3), H(2)S, HCl, AsH(3), and NH(3) are all paired with NH(3) as electron donor. While NH(3) will not engage in an N···N attraction, all the others do form a X···N complex. The energetics, geometries, and other properties of these complexes are relatively insensitive to the nature of the X atom. This uniformity contrasts sharply with the H-bonded XH···N complexes where a strong sensitivity to X is observed. The three-dimensional nature of the electrostatic potential, in conjunction with the striving for a linear H-X···N orientation that maximizes charge transfer, serves as an excellent tool in understanding both the shape of the potential energy surface and the proclivity to engage in a X···N interaction.     

C-X···π halogen and C-H···π hydrogen bonding: interactions of CF3X (X = Cl, Br, I or H) with ethene and propene

Using FTIR and Raman spectroscopy, the formation of halogen bonded complexes of the trifluorohalomethanes CF(3)Cl, CF(3)Br and CF(3)I with ethene and propene dissolved in liquid argon has been investigated. For CF(3)Br and CF(3)I, evidence was found for the formation of C-X···π halogen bonded 1:1 complexes. At a higher ratio of CF(3)I/propene, weak absorptions due to a 2:1 complex were also observed. Using spectra recorded at different temperatures, the complexation enthalpies for the complexes were determined to be -5.3(2) kJ mol(-1) for CF(3)Br·ethene, -7.5(2) kJ mol(-1) for CF(3)I·ethene, -5.6(1) kJ mol(-1) for CF(3)Br·propene, -8.8(1) kJ mol(-1) for CF(3)I·propene and -16.5(6) kJ mol(-1) for (CF(3)I·)(2)propene. The complexation enthalpies of the hydrogen bonded counterparts, with CF(3)H as the Lewis acid, were determined to be -4.6(4) kJ mol(-1) for CF(3)H·ethene and -5.1(2) kJ mol(-1) for CF(3)H·propene. For both hydrogen bonded complexes, a blue shift, by +4.8 and +4.0 cm(-1), respectively, was observed for the C-H stretching mode. The results from the cryospectroscopic study are compared with ab initio calculations at the MP2/aug-cc-pVDZ(-PP) level.     

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 F(3)CX···HMgH···Y and F(3)CX···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.     

OH···X (X = O, S) hydrogen bonding in thetrahydrofuran and tetrahydrothiophene

In this article, hydrogen bonding interaction between p-cresol (p-CR) and cyclic ether, tetrahydrofuran (THF) and thioether, tetrahydrothiophene (THT) has been investigated. Two-color resonantly enhanced two-photon ionization in conjunction with the fluorescence detected IR (FDIR) spectroscopy was used to record the changes in the OH stretching frequency in these complexes. The FDIR spectra showed existence of a single conformer of the p-CR·THF and two conformers of the p-CR·THT complex. With the help of computed IR spectra and atoms-in-molecules analysis, the two conformers of p-CR·THT were assigned as the complex of p-CR with THT (C(2))/THT (C(S)). The redshift of OH stretching frequency for the p-CR·THF complex was greater compared to those for the conformers of the p-CR·THT complex. The binding energies of the p-CR·THF and p-CR·THT complexes were computed to be 7.42 and 6.15 kcal/mole. These were of the same order as those for the acyclic analogs, diethylether (DEE), and diethylsulfide (DES), of the solvent molecules under investigation. Although the DEE and THF consist of same number of carbon atoms, the dispersion energy contribution was much higher (43%) for DEE than that for THF (30%). In the case of sulfur analogs, however, it was similar (~50%) in the case of both DES well as THT complexes. All the computed H-bond indicators for these two complexes nicely correlate with the observed redshift of the O-H stretch.     

Prediction and characterization of HCCH···AuX (X = OH, F, Cl, Br, CH3, CCH, CN, and NC) complexes: a π Au-bond

In this article, we performed quantum chemical calculations to study the π Au-bond in the HCCH···AuX (X = OH, F, Cl, Br, CH(3), CCH, CN, and NC) system. For comparison, we also investigated the HCCH···Au(+) and H(2)CCH(2)···AuF complexes. The equilibrium geometries and infrared spectra at the MP2 level were reported. The interaction energies were calculated at the MP2 and coupled-cluster single double triple levels. The natural bond orbital results support the Dewar-Chatt-Duncanson model. Moreover, we focused on the influence of X atom on the geometries, interaction energies, and orbital interactions as well as the comparison between HCCH···AuF and H(2)CCH(2)···AuF complexes. Although the π Au-bond in these complexes is electrostatic in nature, the weight of covalent nature is also important.     

S···X halogen bonds and H···X hydrogen bonds in H2CS-XY (XY = FF, ClF, ClCl, BrF, BrCl, and BrBr) complexes: cooperativity and solvent effect

Using ab initio calculations, we have studied the structures, properties, and nature of halogen bonds in H(2)CS-XY (XY = FF, ClF, ClCl, BrF, BrCl, and BrBr) complexes. The results show that the ring-shaped complexes are formed by a halogen bond (S···X) and a secondary hydrogen bond (H···X). We also analyzed the H(2)CS-ClF-ClF and FCl-H(2)CS-ClF complexes to investigate the cooperative and diminutive halogen bonding. The cooperative effect of halogen bonding is found in the former, while the diminutive effect is present in the latter. We finally considered the solvent effect on the halogen bond in H(2)CS-BrCl complex and found that the solvent has a prominent enhancing effect on it. The complexes have also been analyzed with natural bond orbital, atoms in molecules, and symmetry adapted perturbation theory method.     

The Lewis basicity of nitrido complexes. Theoretical investigation of the structure and bonding of Cl2 (PH3)3ReN–X (X = BH3, BCl3, BBr3, AlH3, AlCl3, AlBr3, GaH3, GaCl3, GaBr3, O, S, Se, Te)

Quantum chemical calculations using gradient-corrected density functional theory (B3LYP) and ab initio methods at the MP2 level are reported for the geometries and bond energies of the nitrido complexes Cl₂ (PH₃)₃ReN–X (X = BH₃, BCl₃, BBr₃, AlH₃, AlCl₃, AlBr₃, GaH₃, GaCl₃, GaBr₃, O, S, Se, Te). The theoretical geometries are in excellent agreement with experimental values of related complexes which have larger phosphine ligands. The parent nitrido complex Cl₂(PH₃)₃ReN is a very strong Lewis base. The calculated bond dissociation energy of Cl₂(PH₃)₃ReN–AlCl₃ is D _e = 43.7 kcal/mol, which is nearly as high as the bond energy of Me₃N–AlCl₃. The donor-acceptor bonds of the other Cl₂(PH₃)₃ReN–AY₃ complexes are also very strong. Even stronger N–X bonds are predicted for most of the nitrido-chalcogen complexes, which exhibit the trend X = O ≫ S > Se > Te. Analysis of the electronic structure shows that the parent compound Cl₂(PH₃)₃ReN has a Re–N triple bond. The Re–N σ bond is clearly polarized towards nitrogen, while the two π bonds are nearly nonpolar. The Re–N σ and π bonds become more polarized toward nitrogen when a Lewis acid or a chalcogen atom is attached. Bonding in AY₃ complexes should be described as Cl₂(PH₃)₃ReE≡N→AY₃, while the chalcogen complexes should be written with double bonds Cl₂(PH₃)₃Re=N=X. The charge-decomposition analysis indicates that the nitrogen-chalcogen bonds of the heavier chalcogen complexes with X = S, Se, Te can also be interpreted as donor-acceptor bonds between the nitrido complex acting as a Lewis base and the chalcogen atom with an empty p(σ) orbital acting as a Lewis acid. The nitrido oxo complex Cl₂(PH₃)₃ Re=N=O has a covalent N–O double bond. Received: 27 July 1998 / Accepted: 26 October 1998 / Published online: 16 March 1999     

Small heterocyclics as hydrogen bond acceptors and donors: the case of the C2H3XS···NH3 complexes (X = H, F and CH3)

B3LYP/6-311++G(d,p) calculations were employed in order to examine the molecular parameters of the C₂H₃XS···NH₃ heterocyclic hydrogen-bonded complexes with X = H, F and CH₃. Intermolecular criteria were taken into account when studying the formation of these hydrogen-bonded complexes, such as geometry analysis, charge density quantification and interpretation of the harmonic vibrational spectrum, in which case the appearance of red-shift and blue-shift effects was discussed. It was assumed from the outset that many hydrogen bond types may exist in these systems, and these were investigated using the results of topological integrations from the quantum theory of atoms in molecules (QTAIM) and intermolecular charge transfer calculations using the ChelpG scheme. The proton donor/acceptor behavior of C₂H₃XS was interpreted in terms of hydrogen bond energies, whose values were corrected using the basis sets superposition error (BSSE) and zero point energy (ZPE). Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Halogen as halogen-bonding donor and hydrogen-bonding acceptor simultaneously in ring-shaped H3N·X(Y)·HF (X = Cl, Br and Y = F, Cl, Br) complexes

A series of ring-shaped molecular complexes formed by H(3)N, HF and XY (X = Cl, Br and Y = F, Cl, Br) have been investigated at the MP2/aug-cc-pVTZ level of theory. Their optimized geometry, stretching mode, and interaction energy have been obtained. We found that each complex possesses two red-shifted hydrogen bonds and one red-shifted halogen bond, and the two hydrogen bonds exhibit strong cooperative effects on the halogen bond. The cooperativity among the NH(3)···FH, FH···XY and H(3)N···XY interactions leads to the formations of these complexes. The AIM analysis has been performed at the CCSD(T)/aug-cc-pVQZ level of theory to examine the topological characteristics at the bond critical point and at the ring critical point, confirming the coexistence of the two hydrogen bonds and one halogen bond for each complex. The NBO analysis carried out at the B3LYP/aug-cc-pVTZ level of theory demonstrates the effects of hyperconjugation, hybridization, and polarization coming into play during the hydrogen and halogen bonding formations processes, based on which a clockwise loop of charge transfer was discovered. The molecular electrostatic potential has been employed to explore the formation mechanisms of these molecular complexes.     

Theoretical Evidence of Aromaticity in X3 − (X = B, Al, Ga) Species

We investigated the electronic structure and chemical bonding of the B₃ ^–, Al₃ ^–, and Ga₃ ^– anions, and the gas phase NaB₃, NaAl₃, and NaGa₃ molecules. We found that the ground state of the neutral gas phase salts contains an equilateral triangular anion interacting with a Na⁺ cation. The B₃ ^–, Al₃ ^–, and Ga₃ ^– anions possess two delocalized electrons and are found to be aromatic. The triangular anions have been shown to be related to recently synthesized organometallic compound containing an aromatic -Ga₃ ^2– unit, but they are differ from them by four valence electrons. The reason for earlier appearance of the -orbital in the B₃ ^–, Al₃ ^–, and Ga₃ ^– anions is discussed.     

209Bi NQR in Mixed Oxides 2Bi2O3· B2O3, 3Bi2O3· 5B2O3, and Bi2O3· 3B2O3

It was earlier found from nuclear quadrupole resonance (NQR) measurements and computer modeling that -Bi₂O₃, Bi₃O₄Br and mixed oxides Bi₂O₃· 2Al₂O₃, Bi₂O₃· 2Ga₂O₃, Bi₂O₃· 3GeO₂, and 2Bi₂O₃· 3GeO₂exhibit local ordered magnetic fields from 30 to 200 G. It thus follows that these compounds are not diamagnets in a conventional sence of the word. With the aim of revealing previously unknown magnetic properties in bismuth(III) oxide-based Main Group element compounds, the mixed bismuth–boron oxides 2Bi₂O₃· B₂O₃, 3Bi₂O₃· 5B₂O₃, and Bi₂O₃· 3B₂O₃were prepared and studied using ²⁰⁹Bi NQR. The quadrupole interactions of the ²⁰⁹Bi nuclei and their electronic environment were studied, the crystallochemical features of the compounds were discussed, and the conformity of the ²⁰⁹Bi results to the X-ray structure data was verified. The preliminary tests in the field of a permanent magnet showed that the resonance intensities increase in external magnetic fields, indicating that a magnetism of unknown nature develops in the titled compounds. It was found reasonable to continue studies of the magnetic properties of these compounds using single-crystal ²⁰⁹Bi NQR in external magnetic fields.     

The role of Fe–X···X–Fe contacts in the crystal structures of [(2-iodopyridinium)2FeX4]X (X = Cl, Br)

The analogy of chloride–chloride contacts in compounds containing Fe–Cl1···Cl2–Fe synthons with well-studied organic C–Cl1···Cl2–C interactions has been investigated. The crystal structures of the two tetrahaloferrate(III) salts, [(2-iodopyridinium)₂FeX₄]X (X = Cl, Br) have been determined. Analysis of these two isomorphous structures and related published structures shows that the arrangement of Fe–Cl1···Cl2–Fe synthons is similar to that of C–Cl1···Cl2–C with the Fe–Cl1···Cl2 and Cl1···Cl2–Fe angles being ~150°. While inter-chlorine distances are less than the sum of van der Waals radii in C–Cl1···Cl2–C units, they are equal to, or longer, than the sum of van der Waals radii in the corresponding Fe–Cl1···Cl2–Fe contacts. This might indicate that the arrangement of Fe–Cl1···Cl2–Fe synthons occurs predominately to reduce repulsive forces rather than as a result of attractive forces. However, it is observed that the halide–halide distance in [(2-iodopyridinium)₂FeBr₄]Br is shorter than in the isostructural chloride species, which can be explained by the fact that bromine is softer than chlorine. Several intermolecular forces unite the cations and anions within the crystalline lattice of [(2-iodopyridinium)₂FeX₄]X including N–H···X^?, C–I···X–Fe, N(π)···X–Fe, N(π)···I–C, and Fe–X1···X2–Fe contacts. The calculated electron density and electrostatic potential of the [FeX₄]^? anions and the organic iodopyridinium cations was used to describe the arrangement of these synthons and the hierarchy of the strengths of the respective contacts.     

Preparation and structural characterization of the isomorphous compounds: [Bu4N][Mo3(μ3-O)(μ-X)3(μ-OAc)3 X 3]·(CH3)2CO,X=Cl,Br

The reaction of MoCl₃(H₂O)₃ with a mixture of acetic acid and acetic anhydride in the presence of [N(C₄H₉)₄][BF₄] followed by crystallization from acetone/hexane gives a 77% yield of dark purple [NBu₄][Mo₃OCl₆(OAc)₃]·Me₂CO (1). A similar reaction employing MoBr₃(H₂O)₃ gives purple [NBu₄][Mo₃OBr₆(OAc)₃]·Me₂CO (2) in 50% yield. Also produced in this reaction in low (10–20%) yields are [NBu₄]₂[Mo₄OBr₁₂] · 0.5Me₂CO and [NBu₄]₂[Mo₃OBr₆(OAc)₃] · Me₂CO which will be discussed elsewhere Compounds (1) and (2) are isomorphous, space groupP2₁/n,Z=4 with the following unit cell dimensions, where the values for (1) and (2) are given in that order for each one:a=13.406(4), 13.726(5) Å;b=15.701(4), 15.839(5) Å;c=19.250(5), 19.831(6) Å; =101.61(2), 102.92(3)°. Both (1) and (2) are eight-electron species in which the mean Mo-Mo distances are 2.578(1) Å and 2.597(1) Å, respectively.     

PO2X…PX3/PH2X(X=F,Cl, Br,CH3, NH2)复合物中π-hole磷键作用的电子密度拓扑分析

磷键作为一种新型的分子键合力,因在晶体工程和超分子合成等方面的重要作用而越来越多地引起科研工作者的广泛关注。本文采用量子化学从头算和电子密度拓扑分析等方法,在MP2/aug-cc-pVTZ理论水平上,对PO₂X…PX₃和PO₂X…PH₂X (X = F, Cl, Br, CH₃, NH₂) π型复合物的结构和磷键性质进行了理论研究。研究表明:π-hole磷键复合物存在A和B两种稳定构型,分别以P…P和P…X磷键作用为主。分子中原子(AIM)、非共价作用(NCI)、电子定域函数(ELF)及适应性自然密度划分(AdNDP)分析表明,不同取代基对该类磷键作用的性质产生很大影响:当取代基为给电子基(CH₃, NH₂)时,磷键具有明显的共价作用特征;当取代基为吸电子基(F, Cl, Br)时,构型和取代基不同的磷键分别表现为非共价、部分共价或共价作用特征。自然键轨道(NBO)分析指出,分子间磷键的Wiberg键级的数值越大,磷键的共价性越强,磷键的作用强度越大。构型B的电荷转移主要是PX₃/PH₂X中X原子上的孤对电子转移到PO₂X中π^*(P=O)反键空轨道。     

C6F5X＋（X=Cl,Br,I,CH3）离子的理论研究

用DFT B3LYP方法及6-311G（d,p）,6-311＋G（d,p）和LanL2dz基组,对C6F5X＋（X=Cl,Br,I,CH3）阳离子做了理论研究,优化了它们的电子基态的构型,计算了对应分子的垂直电离势（VIP）和绝热电离势（AIP）.结果表明四种离子的构型的对称点群和对应分子相同,但构型参数有明显差别.B...     

Mixed Amidohalotantalates [Ta(NMe2)3X3]– (X = F,Cl)

Russian Journal of Coordination Chemistry - The anionic tantalum complex (ItBuH)[Ta(NMe2)3Cl3] (I) is synthesized by the reaction of [Ta(NMe2)3Cl2]2 with N-heterocyclic carbene ItBu and is isolated...     

Theoretical study of aluminide clusters Al13X, Al13X−, and Al13X 2 − (X=H, Hal, OH, NH2, CH3, and C6H5)

The structural, electronic, energy, and vibrational characteristics of the Al₁₃X^? and Al₁₃X ₂ ^? clusters, with an aluminum-centered (Al_c) icosahedral cage Al₁₃ and with one or two outer-sphere ligands X=H, F, Cl, Br, OH, NH₂, CH₃, C₆H₅, have been calculated within the B3LYP approximation of the density functional theory using the 6-31G* and 6-311+G* basis sets. In all Al₁₃X^? radicals, the unpaired electron is localized at the cage atom Al* located opposite the Al-X bond. This Al* atom is the most favorable site for attaching the second X ligand of any nature (trans-addition rule). According to the previously suggested molecular model of the valence state of the [Al ₁₃ ^? ] “superatom,” the calculated energies D ₁(Al ₁₃ ^? -X) of addition of the first ligand to the Al ₁₃ ^? anion are about 1 eV lower than the corresponding energies of addition of the second ligand D ₂(XAl ₁₃ ^? -X). The structure of the Al₁₃ cage depends on the nature of the nature of the substituent X and can radically change in going from anions to their neutral congeners. In the lowest-lying Al₁₃X isomer with electronegative substituents X (Hal, OH, NH₂, CH₃, etc.), the aluminum cage has a marquee structure (1, symmetry C _s) with a hexagonal base and a pentagonal “roof.” For Al₁₃X analogues with electropositive ligands X (Al, Li, Na), a tridentate isomer (T, C _3v ) with the X substituent coordinated to a face of the Al₁₃ icosahedron is preferable. In the case of moderately electronegative X ligands (of the H type), the marquee (1) and icosahedral (T) isomers are close in energy. The stretching vibration frequencies of isomers 1 and T differ significantly in magnitude and intensity so that vibrational spectroscopy methods can be especially applicable to their experimental identification.     

Interaction in the ternary complexes of HNO3···HCl···H2O: a theoretical study on energetics, structure, and spectroscopy

Ternary complexes of HNO(3)···HCl···H(2)O were investigated by ab initio calculations with aug-cc-pVDZ and aug-cc-pVTZ basis sets. The results are analyzed in terms of structures, energetics, and infrared vibrational frequencies. In all minima, neither HNO(3) nor HCl becomes ionized. The contribution of the nonadditivity effect, which is significant for hydrogen-bonded clusters, is bigger for the cyclic structures in which HNO(3) acts as a proton donor to HCl, although the global minimum contains HNO(3) donating its proton to a H(2)O molecule.     

Synthesis, characterization and thermal properties of trimetallic N3-Cr[quadruple bond]Cr···M-N3 azide complexes with M = Cr, Mn, Fe, and Co

We report here two novel synthetic pathways toward the preparation of a family of trimetallic diazide compounds of the type Cr(2)M(dpa)(4)(N(3))(2), with M = Cr (10), Mn (4), Fe (5), and Co (11). Reaction of either Cr(2)M(dpa)(4)(OTf)(2) (for M = Mn and Fe) or [Cr(2)M(dpa)(4)(MeCN)(2)](PF(6))(2) (for M = Cr and Co) with sodium azide in methanol leads to the formation of the corresponding diazide compounds, and single crystal X-ray diffraction measurements confirm the predicted structures. Compounds 4, 5, and 10 are all high-spin compounds, but 11 is a spin-crossover compound exhibiting low-spin behavior at low temperatures (~100 K). Thermolytic characterization by DSC and TGA reveals an exothermic reaction corresponding to the loss of two dinitrogen molecules from compounds 5, 10, and 11. Further characterization by solution NMR measurements and cyclic voltammetry are also presented.