Theoretical design of planar molecules with a nona- and decacoordinate central atom

The maximum coordination number of the central atom in planar molecules generated by now in mole-cular beams was 8. We made use of the chemical bond model developed for planar boron clusters to check the possibility of existence of planar molecules with the coordination numbers 9 and 10. The objects of or study were the AlB₉ and AlB ₁₀ ⁺ clusters which have local minima corresponding to highly symmetrical D _9h and D _10h structures, respectively. According to our calculations, the highly symmetrical structure of AlB₉ is a global minimum or a low-lying isomer, and, therefore, it holds promise as a new ligand for coordination chemistry. The energy of the highly symmetrical structure of AlB ₁₀ ⁺ with the coordination number 10 is too high, and this structure is hardly synthetically feasible. Thus, 9 is presently the maximum coordination number of an atom in a planar molecule.     

Photoelectron spectroscopy and Ab initio study of the structure and bonding of Al7N- and Al7N

The electronic and geometrical structures of Al7N- are investigated using photoelectron spectroscopy and ab initio calculations. Photoelectron spectra of Al7N- have been obtained at three photon energies with six resolved spectral features at 193 nm. The spectral features of Al7N- are relatively broad, in particular for the ground state transition, indicating a large geometrical change from the ground state of Al7N- to that of Al7N. The ground state vertical detachment energy is measured to be 2.71 eV, whereas only an upper limit of approximately 1.9 eV can be estimated for the ground state adiabatic detachment energy due to the broad detachment band. Global minimum searches for A7N- and Al7N are performed using several theoretical methods. Vertical electron detachment energies are calculated using three different methods for the lowest energy structure and compared with the experimental data. Calculated results are in excellent agreement with the experimental data. The global minimum structure of Al7N- is found to possess C3v symmetry, which can be viewed as an Al atom capping a face of a N-centered Al6N octahedron. In the ground state of Al7N, however, the capping Al atom is pushed inward with the three adjacent Al-Al distances being stretched outward. Thus, even though Al7N still possesses C3v symmetry, it is better viewed as a N-coordinated by seven Al atoms in a cage-like structure. The chemical bonding in Al7N- is discussed on the basis of molecular orbital and natural bond analysis.     

Structure,microstructure, and dielectric responses of (1–<Emphasis Type="Italic">х</Emphasis>)BiFeO<Subscript>3</Subscript>–<Emphasis Type="Italic">x</Emphasis>BaTiO<Subscript>3</Subscript> solid solutions

The structure, microstructure, and dielectric responses of (1–х)BiFeO₃–xBaTiO₃ (0.0 < x ≤ 0.5) solid solutions prepared as ceramics are studied. Patterns in their dielectric parameters and the formation of their crystal and grain structures are investigated in a wide range of temperatures and frequencies.     

Assessing the Viability of Extended Nonmetal Atom Chains in MnF4n+2 (M=S and Se)

Theoretical investigations to evaluate the viability of extended nonmetal atom chains on the basis of molecular models with the general formula M_nF_4n+2 (M=S and Se) and corresponding solid‐state systems exhibiting direct S? S or Se? Se bonding were performed. The proposed high‐symmetry molecules were found to be minima on the potential energy surface for all S_nF_4n+2 systems studied (n=2–9) and for selenium analogues up to n=6. Phonon calculations of periodic structures confirmed the dynamic stability of the ‐(SF₄–SF₄)_∞‐ chain, whereas the analogous ‐(SeF₄–SeF₄)_∞‐ chain was found to have a number of imaginary phonon frequencies. Chemical bonding analysis of the dynamically stable ‐(SF₄–SF₄)_∞‐ structure revealed a multicenter character of the S? S and S? F bonds. A novel definition and abbreviation (ENAC) are proposed by analogy with extended metal atom chain (EMAC) complexes.     

Reply to the Comment on “Realization of Lewis Basic Sodium Anion in the NaBH3− Cluster”

We reply to the comment by S. Pan and G. Frenking who challenged our interpretation of the Na⁻:→BH₃ dative bond in the recently synthesized NaBH₃⁻ cluster. Our conclusion remains the same as that in our original paper ( https://doi.org/10.1002/anie.201907089 and https://doi.org/10.1002/ange.201907089 ). This conclusion is additionally supported by the energetic pathways and NBO charges calculated at UCCSD and CASMP2(4,4) levels of theory. We also discussed the suitability of the Laplacian of electron density (QTAIM) and Adaptive Natural Density Partitioning (AdNDP) method for bond type assignment. It seems that AdNDP yields more sensible results. This discussion reveals that the complex realm of bonding is full of semantic inconsistencies, and we invite experimentalists and theoreticians to elaborate this topic and find solutions incorporating different views on the dative bond.     

Device for measuring doping impurities of Groups III and V in high-purity silicon by long-wavelength spectroscopy

An experimental installation for analyzing electrically active impurities in high-purity silicon by investigating low-temperature transmission spectra withcompensation for donor-acceptor impurities is fabricated. The applicability of the method for studying both high-purity and doped silicon wafers is shown.Software for automatically computing the concentration of impurities is developed.     

Aluminum avoids the central position in AlB9- and AlB10-: photoelectron spectroscopy and ab initio study

The structures and the electronic properties of two Al-doped boron clusters, AlB(9)(-) and AlB(10)(-), were investigated via joint photoelectron spectroscopy and high-level ab initio study. The photoelectron spectra of both anions are relatively broad and have no vibrational structure. The geometrical structures were established by unbiased global minimum searches using the Coalescence Kick method and comparison between the experimental and calculated vertical electron detachment energies. The results show that both clusters have quasi-planar structures and that the Al atom is located at the periphery. Chemical bonding analysis revealed that the global minimum structures of both anions can be described as doubly (σ- and π-) aromatic systems. The nona-coordinated wheel-type structure of AlB(9)(-) was found to be a relatively high-lying isomer, while a similar structure for the neutral AlB(9) cluster was previously shown to be either a global minimum or a low-lying isomer.     

ChemInform Abstract: Observation of the Highest Coordination Number in Planar Species: Decacoordinated Ta©B10‐ and Nb©B10‐ Anions.

TaB₁₀^‐ and NbB₁₀^‐ clusters are produced in a laser‐vaporization supersonic molecular beam cluster source and characterized by photoelectron spectroscopy.     

Transition-metal-centered nine-membered boron rings: MⓒB9 and MⓒB9(-) (M = Rh, Ir)

We report the observation of two transition-metal-centered nine-atom boron rings, Rh?B(9)(-) and Ir?B(9)(-). These two doped-boron clusters are produced in a laser-vaporization supersonic molecular beam and characterized by photoelectron spectroscopy and ab initio calculations. Large HOMO-LUMO gaps are observed in the anion photoelectron spectra, suggesting that neutral Rh?B(9) and Ir?B(9) are highly stable, closed shell species. Theoretical calculations show that Rh?B(9) and Ir?B(9) are of D(9h) symmetry. Chemical bonding analyses reveal that these complexes are doubly aromatic, each with six completely delocalized π and σ electrons, which describe the bonding between the central metal atom and the boron ring. This work establishes firmly the metal-doped B rings as a new class of novel aromatic molecular wheels.