A donor-stabilization strategy for the preparation of compounds featuring P=B and As=B double bonds

A new class of heavier group 15 compounds demonstrating multiple bonding with boron has been synthesized using a simple donor-stabilization protocol.     

Single-Nitrogen Atom Incorporation into B=B Bond via the N=N Bond Splitting of Diazo Compound and Diazirine

Triboraazabutenyne 3 is synthesized by the reaction of diboraazabutenyne 1 with aryl boron dibromide followed by the reduction. The ligand exchange to replace phosphine on the terminal sp² B atom with carbene furnishes 4 . ¹¹B NMR, solid-state structures, and computational studies disclose that 3 and 4 feature the extremely polarized B=B bond. 4 readily splits the N=N bond of both diazo compound and diazirine under ambient conditions, whereby one nitrogen atom is incorporated into the B=B moiety leading to a neutral diboraazaallene 6 . The mechanism of the reaction between 4 and diazo compound is extensively investigated by density functional theory (DFT) calculations, as well as the isolation of an intermediate.     

Mischkristalle aus A4B3-Molekülen (A = P,As; B = S,Se)

Mixed Crystals from A₄B₃ Molecules (A = P, As; B = S, Se) The system P₄S₃? P₄Se₃? As₄S₃? As₄Se₃ was investigated by thermal and x-ray methods. Five regions of solid solubility with different crystal structures were found at room temperature. The range of existence can be influenced by the temperature of annealing. All these phases transform into a plastic-crystalline modification with complete solid solubility at higher temperature. A decomposition reaction of the A₄B₃ molecules was observed in the P₄Se₃/As₄Se₃/As₄S₃ part of the system. The molecules decompose into A₄B₄ molecules and an amorphous phase. The existence of all molecules of the type P_nAs_4–nS_mSe_3–m (n = 0–4, m = 0–3) and also As₄S_mSe_4–m (m = 1–3) was verified by mass spectrometric measurements. The thermochemical data of the mixed crystals are determined by the type of the constituent A₄B₃ molecules. The temperature and the entropy of the α–β transition are lower for mixed crystals, formed by substituted molecules, than for those of the same structure, consisting of pure A₄B₃ molecules.     

Syntheses,Crystal Structures,and Optical Properties of the Hexagonal Perovskites Variants ABX3 (B = Ni,A = Gu,FA, MA,X = Cl,Br; B = Mn,A = MA,X = Br)

Herein we report on our systematic investigations on the solution processed synthesis and characterization of transition metal halides (guanidinium, formamidinium, and methylammonium nickel bromides and chlorides as well as methylammonium manganese bromide) with the composition ABX₃ (A = organic cation; B = Mn, Ni; X = Cl, Br). The investigations were carried out with respect to possible applications of 3d transition metal compounds for the perovskite solar cell. All the compounds represent different variants of the hexagonal perovskite structure (2H). Crystal structures and symmetry relations are discussed. Additionally, (CH₃NH₃)₂MnI₄, which consists of tetrahedral coordinated Mn²⁺, and the water containing compounds (CH₃NH₃)MnBr₃ · 2H₂O, which forms chains of edge sharing octahedra, as well as (CH₃NH₃)NiCl₃ · 2H₂O, which consists of dimers of octahedra, are presented. Investigations on the crystal structures are supported by vibrational and optical spectroscopy.     

Synthesis and Trapping of Iminoboranes by M=B/C=N Bond Metathesis

Although the metathesis of metal–boron double bonds with elemental chalcogenides is an established process, no similar reactivity has been observed with element–nitrogen bonds. Such a reaction would provide a new route to iminoborane compounds (RB≡NR′), which have recently experienced renewed synthetic interest. Herein, we present the first observation of M=B/C=N metathesis reactions, which led to the isolation of a stable iminoborane in addition to further iminoborane cycloaddition products.     

Boron-pnictogen multiple bonds: donor-stabilized P=B and As=B bonds and a hindered iminoborane with a B-N triple bond

Reaction of the hindered phosphino- and arsinoboranes, Ar*Pn(H)-B(Br)Tmp (Ar* = -C6H3-2,6-(C6H2-2,4,6-iPr3)2; Tmp = 2,2,6,6-tetramethylpiperidino; Pn = P and As, 1 and 3, respectively) with 4-dimethylaminopyridine, DMAP, afforded the boranylidenephosphane and arsane, Ar*Pn=B(DMAP)Tmp (Pn = P and As, 2 and 4) as deep red-purple solids. The analogous aminoboranes Ar'N(H)-B(X)Tmp (Ar' = -C6H3-2,6-(C6H2-2,4,6-Me3)2; X = Cl and Br; 5 and 6) did not display any reactivity with DMAP, but in the presence of the amide base, Na[N(SiMe3)2], the clean formation of the uncomplexed iminoborane Ar'NBTmp (7) was observed. Attempts to generate an Sb=B bond were unsuccessful, as the required stibinoborane precursor, Ar*Sb(H)-B(Br)Tmp, could not be prepared; in place of clean Sb-B bond formation, the reduced product Ar*Sb=SbAr* was obtained. All compounds were characterized spectroscopically, and the X-ray crystal structures of 1, 2, 4, 6, and 7 were determined.     

FT-NMR investigation of 13C?11B coupling

The ¹³C FT-NMR spectrum of sodium tetraphenylboron obtained with proton decoupling has a line-shape which suggests the operation of a magnetic-dipole relaxation mode. Coupling constants between ¹¹B and the ring carbons are reported.     

(XY)12(X=B,Al;Y=P)团簇的结构与稳定性

采用B3LYP／6031G*方法,对(XY)12(X=B,Al;Y=P)笼状团簇的同分异构体进行优化,筛选出能量最低的构型．讨论它们的几何构型、HOMO-LUMO能隙、生成焓、核独立化学位移(NICS)和自由能．得到(BP)12和(AlP)12团簇的最稳定构型均为具有Th对称性的四、六元环组成的笼,亚稳态结构中含有五元环。     

Incorporation of trivalent cations in synthetic garnets A3B5O12 (A = Y, Lu-La, B = Al, Fe, Ga)

Static-lattice atomistic calculations have been used to study the solution energy for the incorporation of 13 foreign cations at 3 different lattice positions of 12 synthetic garnets. Trends have been obtained as a function of the ionic radius of the dopant cation, and the predictions about site preference have been compared with both literature and experimental data. The preferred substitution site is mainly determined by the ionic size and has been correctly predicted in all cases. Moreover, the energy difference between the preferred substitution site and the next favored site is relatively small in several cases, and hence the foreign ions can be inserted at two different positions by using the correct stoichiometry. A remarkably different behavior has been encountered for Al garnets, due to the smaller size of the unit cell. In particular, some cations, such as Fe3+ and Ga3+, can be inserted at the dodecahedral position usually occupied by the rare-earth ion. Despite the limitations of the static-lattice approach, the results of the present simulations help in the understanding of the defect chemistry of garnets, which is strongly responsible for the physicochemical properties (such as luminescence and ferrimagnetism) that make garnets interesting for technological applications. Such results lead to the possibility of tuning the optical and luminescence properties of garnets by the formation of different types of solid solutions.     

不饱和硼烯HClN=B:重排反应的DFT研究

采用量子化学中的密度泛函方法, 在B3LYP/6-311G**水平上研究了不饱和硼烯HClN=B:的重排反应机理。结果表明, 无论是氢原子H迁移还是氯原子Cl迁移都经过1个三元环过渡态,生成直线型产物。但氢原子H迁移是在面内进行, 而氯原子Cl迁移是在面外进行。根据计算结果,详细研究了不饱和硼烯HClN=B:重排反应的热力学及动力学函数, 在此基础上讨论了不饱和硼烯HClN=B:的存在寿命问题。     

Magnetische Eigenschaften der Verbindungsreihe EuBX mit B = Element der ersten Neben- und X = Element der fünften Hauptgruppe

Magnetic Properties of the Compound Series EuBX with B = Element of the First Subgroup and X = Element of the Fifth Main Group The magnetic properties of the compounds EuBX (B ? Cu, Ag, Au; X ? P, As, Sb, Bi) in the temperature range between 3.8 and 300 K are reported. These compounds crystallize in a modified Ni₂In-type structure. The compounds EuCuP, EuAgP, EuAuP, and EuAuAs show at low temperatures ferromagnetic behaviour, EuCuAs and EuAgAs are metamagnetic. According to our measurements this seems to be the same with EuCuSb, EuAgSb, EuAuSb, and EuAuBi whereas EuCuBi and EuAgBi show antiferromagnetic interaction.     

TM7TM'6B8 (TM = Ta, Nb; TM' = Ru, Rh, Ir): new compounds with [B6] ring polyanions

The ternary boron compounds TM(7)TM'(6)B(8) (TM = Ta, Nb; TM' = Ru, Rh, Ir) were prepared by high-temperature thermal treatment of mixtures of the elements. An analysis of the chemical bonding by the electron density/electron localizability approach reveals formation of covalently bonded polyanions [B(6)] and [TM'(6)B(2)]. The cationic part of the structure contains separated TM cations. In agreement with the chemical bonding analysis and band structure calculations, all TM(7)TM'(6)B(8) compounds are metallic Pauli-paramagnets (TM' = Ru, Rh) or diamagnets (TM' = Ir).     

Quantitative determination of compounds in mixtures by B2E=constant linked scans

The B²E = constant linked scan is shown to be an excellent tool for quantifications with reversed geometry mass spectrometers. Deuterium-labelled analogues may be used as internal standards, thus providing very simple clean-up procedures. The principle is demonstrated with the example of chloro-substituted benzoic acid methyl esters. Possible interferences arising from isotope peaks are discussed. The method is applied to the quantification of caffeine in beverages.     

Iminopropadienethiones, Ar=N=C=C=C=S

Aryliminopropadienethiones 9 have been generated by flash vacuum thermolysis of isoxazolones of the type 5 and characterized by mass spectrometry and matrix isolation IR spectroscopy in conjunction with DFT calculations and chemical trapping.