Non-conventional hydrogen bonding and dispersion forces that support embedding mesitylgold into a tailored bis(amidine) framework

A bis(amidine) ligand operates as a molecular lock for two AuMes fragments. The resulting complex retains a flexible double macrocycle with two non-conventional N–H∙∙∙Cipso hydrogen bonds and distinct intramolecular dispersion...

Revisiting the chevrel phase: Impact of dispersion corrections on the properties of Mo6S8 for cathode applications

While the Mo6S8 chevrel phase is frequently used as cathode material in Mg--ion batteries, theoretical studies on this material are comparatively scarce. The particular structure of the Mo6S8 phase, with rather loosely connected cluster entities, points to the important role of dispersion forces in this material. However, so far this aspect has been completely neglected in the discussion of Mo6S8 as cathode material for mono- and multivalent-ion batteries. In this work we therefore have studied the impact of dispersion forces on stability and kinetics of Mo6S8 intercalation compounds. For this purpose, a series of charge carriers (Li, Na, K, Mg, Ca, Zn, Al) has been investigated. Interestingly, dispersion forces are observed to only slightly affect the lattice spacing of the chevrel phase, nevertheless having a significant impact on insertion voltage and in particular on the charge carrier mobility in the material. Moreover, upon varying the charge carriers in the chevrel phase, their diffusion barriers are observed to scale linearly with the ion size, almost independent of the charge of the considered ions. This indicates a rather unique and geometry dominated diffusion mechanism in the chevrel phase. The consequences of these findings for the ion mobility in the chevrel phase will be carefully discussed.

Synthetic and Structural Study of peri-Substituted Phosphine-Arsines

A series of phosphorus-arsenic peri-substituted acenaphthene species have been isolated and fully characterised, including single crystal X-ray diffraction. Reactions of EBr3 (E = P, As) with iPr2PAcenapLi (Acenap = acenaphthene-5,6-diyl) afforded the thermally stable peri-substitution supported donor–acceptor complexes, iPr2PAcenapEBr23 and 4. Both complexes show a strong P→E dative interaction, as observed by X-ray crystallography and 31P NMR spectroscopy. DFT calculations indicated the unusual As∙∙∙As contact (3.50 Å) observed in the solid state structure of 4 results from dispersion forces rather than metallic interactions. Incorporation of the excess AsBr3 in the crystal structure of 3 promotes the formation of the ion separated species [iPr2PAcenapAsBr]+Br− 5. A decomposition product 6 containing the rare [As6Br8]2– heterocubane dianion was isolated and characterised crystallographically. The reaction between iPr2PAcenapLi and EtAsI2 afforded tertiary arsine (BrAcenap)2AsEt 7, which was subsequently lithiated and reacted with PhPCl2 and Ph2PCl to afford cyclic PhP(Acenap)2AsEt 8 and acyclic EtAs(AcenapPPh2)2 9.

A Density Functional Theory Investigation of Intramolecular Dispersion Forces in Buckyball-Buckybowl Complexes

<p>The electron-rich, concave face of corannulene makes it an ideal candidate to host electron-deficient fullerenes, such as C60. The host–guest system is dominated by weak van derWaals interactions. Modelling of the C60@corannulene complex was carried out with nine different density functionals: B3LYP, B97-D, BP86, CAM-B3LYP, M06-2X, PW91, t-HCTH, wB97X, and wB97X-D, using the 6-31G(d) basis set. Results indicated that the functionals including an empirical dispersion correction term, B97-D and wB97X-D, gave the most reliable binding energy values when compared with ab initio SCS-MP2 benchmark computations. Additionally, a number of complexes with functionalised corannulene bowls were modelled at the wB97X-D/6-31G(d) level, with NMR calculations performed at the GIAO/wB97X-D/dec-6-31G(d) level. A linear trend was revealed between the number of substituents on corannulene and the strength of binding within complex with C60. Calculated 1H NMR Dd values for methyl groups on methyl substituted corannulene bowls were also linearly dependent on binding energy. Further results are reported here.</p>

A Density Functional Theory Investigation of Intramolecular Dispersion Forces in Buckyball-Buckybowl Complexes

<p>The electron-rich, concave face of corannulene makes it an ideal candidate to host electron-deficient fullerenes, such as C60. The host–guest system is dominated by weak van derWaals interactions. Modelling of the C60@corannulene complex was carried out with nine different density functionals: B3LYP, B97-D, BP86, CAM-B3LYP, M06-2X, PW91, t-HCTH, wB97X, and wB97X-D, using the 6-31G(d) basis set. Results indicated that the functionals including an empirical dispersion correction term, B97-D and wB97X-D, gave the most reliable binding energy values when compared with ab initio SCS-MP2 benchmark computations. Additionally, a number of complexes with functionalised corannulene bowls were modelled at the wB97X-D/6-31G(d) level, with NMR calculations performed at the GIAO/wB97X-D/dec-6-31G(d) level. A linear trend was revealed between the number of substituents on corannulene and the strength of binding within complex with C60. Calculated 1H NMR Dd values for methyl groups on methyl substituted corannulene bowls were also linearly dependent on binding energy. Further results are reported here.</p>

Tris[triphenylantimony(V)]hexa(μ-oxido)tellurium(VI): a molecular complex with six Te—O—Sb bridges

In the structure of the title compound [systematic name hexa-μ-oxido-1:2κ4 O:O;1:3κ4 O:O;1:4κ4 O:O-nonaphenyl-2κ3 C,3κ3 C,4κ3 C-triantimony(V)tellurium(VI)], [Sb3Te(C6H5)9O6], the hexaoxidotellurate(VI) ion is coordinated to three SbV ions via pairs of cis-positioned O atoms to form a discrete molecular unit. The TeVI and SbV central ions exhibit distorted octahedral [TeO6] and distorted trigonal–bipyramidal [SbC3O2] coordination geometries, respectively. The linking of these polyhedra, by sharing the dioxide edges, results in the Te-based octahedron having a mer-configuration. The packing of the molecules is dominated by C—H...O hydrogen bonding and weak dispersion forces, with a minor contribution from C—H...π bonds and π–π stacking interactions. According to the Hirshfeld surface analysis, the contributions of the H...H, H...C/C...H and H...O/O...H contacts are 58.0, 32.6 and 7.8%, respectively. The title structure provides a model for the bonding of triorganoantimony dications to octahedral oxoanions, and the observed doubly bridged motifs, Te(μ-O)2Sb, may find application in the functionalization of polyoxometalate species.

Contribution of Nitrogen Heteroatom to Anion-π Interaction of N-heterocyclic Anthracene C14-2mH10-2mN2m (m = 1, 2, and 3) with Chloride Anion

N-heterocyclic aromatic in anion-π interaction has been playing a crucial role in a host of chemical and biological processes. In the present contribution, several different complexes composed of N-heterocyclic anthracene C14-2mH10-2mN2m (m = 1, 2, and 3) and chloride anion are investigated at the atomic level. We find that anion-π interactions are enhanced with the increasing number of N atoms. In addition, positions of nitrogen heteroatoms also have a significant effect on this interaction. Contributions of α, β and γ N atoms are in order of Nβ>Nγ>Nα. Moreover, energy decomposition analysis indicates that electrostatic interactions are the dominant stabilizing forces when chloride anion locates above aromatic ring, while the influence of other terms becomes significant when chloride anion deviates from aromatic ring. It is worth noting that dispersion forces play an important role in those anion-π interactions.