Theoretical study on halide and mixed halide Perovskite solar cells: Effects of halide atoms on the stability and electronic properties

Increasing the stability of perovskite solar cells is one of the most important tasks in the photovoltaic industry. Thus, the structural, energetic, and electronic properties of pure CH₃NH₃PbI₃ and fully doped compounds (CH₃NH₃PbBr₃ and CH₃NH₃PbCl₃) in cubic and tetragonal phases were investigated using density functional theory calculations. We also considered the effects of mixed halide perovskites CH₃NH₃PbI₂X (where X = Br and Cl) and compared their properties with CH₃NH₃PbI₃. The DFT results indicate that the phase transformation from tetragonal to cubic phase decreases the band gap. The calculated results show that the X‐site ion plays a vital role in the geometrical stability and electronic levels. An increase in the band gap and a reduction in the lattice constants are more apparent in CH₃NH₃PbI₂X compounds (I > Br > Cl).     

Solvolysis Products of the Types [RhMeL2(Me3[9]aneN3)]2+ and [RuCl3—XLX(Me3[9]aneN3)](x)+ (x = 1‐2) and Preparation and Structure of [Ru([9]aneS3)(Me3[9]aneN3)](CF3SO3)2

Solvolysis of [RhMe(CF₃SO₃)₂(Me₃[9]aneN₃)] ( 1 ) (Me₃[9]aneN₃ = 1, 4, 7‐trimethyl‐1, 4, 7‐triazacyclononane) in CH₃CN, DMSO or pyrazole (L) leads to substitution of both trifluoromethylsulfonate ligands and formation of the cationic complexes [RhMeL₂(Me₃[9]aneN₃)](CF₃SO₃)₂ 3—5 . In contrast, treatment of [RuCl₃(Me₃[9]aneN₃)] ( 2 ) with Ag(CF₃SO₃) in a 1:3 ratio for 2h in CH₃CN leads to formation of the tetranuclear complex [{RuCl₃(Me₃[9]aneN₃)}₂Ag₂(CF₃SO₃)(CH₃CN)](CF₃SO₃) · CH₃CN ( 6 ) with a novel [(RuCl₃)₂Ag₂] core. More forcing conditions enable the substitution of respectively one or two chloride ligands by CH₃CN (reflux 18h) or DMF (85°C, 1h) to afford [RuCl₂(CH₃CN)(Me₃[9]aneN₃)](CF₃SO₃) ( 7 ) and [RuCl(DMF)₂(Me₃[9]aneN₃)](CF₃SO₃)₂ ( 8 ). The heteroleptic sandwich complex [Ru([9]aneS₃)(Me₃[9]aneN₃)](CF₃SO₃)₂ ( 9 ) can be prepared by reduction of 2 with Zn powder in acetone in the presence of 3 equiv. of Ag(CF₃SO₃), followed by addition of [9]aneS₃ (1, 4, 7‐trithiacyclononane). The redox potential E°(Ru³⁺/Ru²⁺) of +1.87 V vs NHE for 9 is only —0.12 V lower than that of the homoleptic complex [Ru([9]aneS₃)₂]²⁺. Crystal structures are reported for 3 — 9 .     

Synthese,Strukturuntersuchung und Reaktionen Phosphansubstituierter Derivate von Fe3(CO)9(μ3-CF)2

Syntheses, Structure Determination and Reactions of Phosphine Substituted Derivatives of Fe₃(CO)₉(μ₃-CF)₂ Photolysis of Fe₃(CO)₉(μ₃-CF)₂ 1 in the presence of acetonitrile 2a or benzoenitrile 2b results in the substitution of a single carbonyl ligand by a nitrile ligand yielding Fe₃(CO)₈(CH₃CN)(μ₃-CF)₂ 3a and Fe₃(CO)₈(C₆H₅CN)(μ₃-CF)₂ 3b, respectively. The acetonitrile ligand in 3a can be easily replaced by trimethyl-phosphine 4a or triphenylphosphine 4b . The monosubstituted compounds Fe₃(CO)₈(PR₃)(μ₃-CF)₂5, R = CH₃ a, R = C₆H₅, b are obtained as major products besides a small amount of the disubsituted products Fe₃(CO)₇(PR₃)₂(μ₃-CF)₂ 6. The structure of 5a has been elucidated by a single crystal X-ray structure determination. Thermal ligand substitution in 1, however, results in the formation of a mixture of mono-, disubstituted, and trisubstituted products, in which 6b is the major product for diphenylphosphine. 5a reacts with ethyne 7 forming a phosphine substituted diferra-allyl-cluster Fe₃(CO)₇(PR₃)(μ₃-CF)(μ₃? CF? CH? CH) 8. The structure of one isomere of 8 has been determinated by X-ray crystallography.     

N-Silylierung und Si?O-Bindungsspaltung bei der Reaktion lithiierter Siloxy-silylamino-silane mit Chlortrimethylsilan

N-Silylation and Si? O Bond Splitting at the Reaction of Lithiated Siloxy-silylamino-silanes with Chlorotrimethylsilane Lithiated Siloxy-silylamino-silanes were allowed to react in tetrahydrofurane (THF) and in n-octane (favoured) and n-hexane, resp., with chlorotrimethylsilane. The monoamide (Me₃SiO)Me₂Si(NLiSiMe₃) gives in THF and in n-octane the N-substitution product (Me₃SiO)Me₂Si · [N(SiMe₃)₂] 1 , the diamide (Me₃SiO)MeSi(NLiSiMe₃)₂ only in THF the N-substitution products (Me₃SiO)MeSi[N(SiMe₃)₂]₂ 2 (main product) and (Me₃SiO)MeSi[N(SiMe₃)₂](NHSiMe₃) 3 . In n-octane the diamide reacts mainly under Si? O bond splitting. The cyclodisilazane [(Me₃SiNH)MeSi? NSiMe₃]₂ 6 is obtained as the main product. Byproducts are 2, 3 and the tris(trimethylsilylamino) substituted disilazane (Me₃SiO)(Me₃SiNH)MeSi? N · (SiMe₃)? SiMe(NHSiMe₃)₂ 7 . The triamide (Me₃SiO)Si · (NLiSiMe₃)₃ reacts under Si? O and Si? N bond splitting in n-octane as well as in THF. The cyclodisilazanes [(Me₃SiNH)₂ · Si? NSiMe₃]₂ 10 and ( 11 : R = Me₃SiNH, 12 : R = (Me₃Si)₂N) are formed. in THF furthermore the N-substitution products (Me₃SiO)Si[N(SiMe₃)₂] · (NHSiMe₃)₂ 4 and (Me₃SiO)Si[N(SiMe₃)₂]₂(NHSiMe₃) 5 . The Si? O bond splitting occurs in boiling n-octane also in absence of the chlorotrimethylsilane. An amide solution of (Me₃SiO)MeSi(NHSiMe₃)₂ with n-butyllithium in the molar ratio 1 : 1 leads in n-octane and n-hexane to 6 and 7 , in THF to 3 . The amide solutions of (Me₃SiO)Si · (NHSiMe₃)₃ with n-butyllithium the molar ratio 1 : 1 and 1 : 2 give in THF 4 and 5 , respectively.     

Triphenylphosphane Oxide Complexes of Lanthanide Nitrates: Polymorphs and Photophysics

A series of mer‐[Ln(NO₃)₃(Ph₃PO)₃] complexes were prepared from Ln(NO₃)₃ · xH₂O and Ph₃PO in chloroform (Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, and Er). The La and Nd complexes were 0.25 CHCl₃ solvates, whereas the others were solvent‐free. The identical reaction using Yb(NO₃)₃ · xH₂O produced the unique salt trans‐[Yb(NO₃)₂(Ph₃PO)₄][Yb(NO₃)₄(Ph₃PO)] · Et₂O. All nitrate ions in all complexes are η²‐chelating. A comparison of the various [Ln(NO₃)₃(Ph₃PO)₃] structures, including those in the literature, reveals at least four common polymorphs, each of which is represented by isomorphic structures of multiple Ln ions. Luminescence of mer‐[Ln(NO₃)₃(Ph₃PO)₃] (Ln = Y, La, Nd, Sm, Eu, Gd, Tb, and Dy), trans‐[Yb(NO₃)₂(Ph₃PO)₄][Yb(NO₃)₄(Ph₃PO)] and Ph₃PO assignments are reported. Latva's empirical rule allows for the antenna effect, in which energy is transferred from the triplet state of the Ph₃PO ligand, to occur only for Tb³⁺. Excitation via Ph₃PO results in strong green luminescence for Tb³⁺ having twice the intensity as that which results from direct excitation of the f‐f transitions.     

Cleavage and rearrangement of phosphorus-carbon and phosphine-metal bonds in alkyltris(tertiary phosphine)cobalt compounds

Complexes of the type L₃CoCH₃ have been prepared in which L = Ph₃P, P₂PCH₃, PhP(CH₃)₂, Ph₂PGe(CH₃)₃, Ph₂PSn(CH₃)₃, Ph₃As, and R = CH₃, Ph, and (CH₃)₃Si. Decomposition of these complexes under mild conditions in several solvents has been studied. Among the identified products are benzene, toluene, biphenyl, and rearranged phosphines, such as Ph₃P from [Ph₂PCH₃]₃CoCH₃ or Ph₂PCH₃ from [Ph₂PGe(CH₃)₃]₃CoCH₃.     

Sr3(BS3)2 und Sr3(B3S6)2: Zwei neue nicht‐oxidische Chalkogenoborate mit trigonal‐planar koordiniertem Bor

Sr₃(BS₃)₂ and Sr₃(B₃S₆)₂: Two Novel Non‐oxidic Chalcogenoborates with Boron in a Trigonal‐Planar Coordination The thioborates Sr₃(BS₃)₂ and Sr₃(B₃S₆)₂ were prepared from strontium sulfide, amorphous boron and sulfur in solid state reactions at a temperature of 1123 K. In a systematic study on the structural cation influence on this type of ternary compounds, the crystal structures were determined by single crystal X‐ray diffraction. Sr₃(BS₃)₂ crystallizes in the monoclinic spacegroup C2/c (No. 15) with a = 10.187(4) Å, b = 6.610(2) Å, c = 15.411(7) Å, β = 102.24(3)° and Z = 4. The crystal structure of Sr₃(B₃S₆)₂ is trigonal, spacegroup R3¯ (Nr. 148), with a = 8.605(1) Å, c = 21.542(4) Å and Z = 3. Sr₃(BS₃)₂ contains isolated [BS₃]^3— anions with boron in a trigonal‐planar coordination. The strontium cations are found between the layers of orthothioborate anions. Sr₃(B₃S₆)₂ consists of cyclic [B₃S₆]^3— anions and strontium cations, respectively.     

[(Ph3Sn)3VO4]·CH3CN und [(Ph3Sn)3VO4]·2 DMF,Triphenylzinnvanadate mit neuartigen Kettenstrukturen

[(Ph₃Sn)₃VO₄]·CH₃CN and [(Ph₃Sn)₃VO₄]·2 DMF, Triphenyltin Vanadates with Novel Chain Structures The reaction of Na₃VO₄ with Ph₃SnCl in a water/CH₂Cl₂ mixture leads to the formation of [(Ph₃Sn)₃VO₄] ( 1 ). Recrystallization of 1 from toluene/CH₃CN gives pale yellow crystals of [(Ph₃Sn)₃VO₄]·CH₃CN ( 2 ). 2 crystallizes as coordination polymer which consists of infinite chains composed of corner‐sharing VO₄ tetrahedra and Ph₃SnO₂ trigonal bipyramides. Additionally the VO₄ groups are connected to two terminal SnPh₃‐Groups containing tin atoms in a tetrahedral environment. [(Ph₃Sn)₃VO₄]·2 DMF ( 3 ) which is obtained from Na₃VO₄ and Ph₃SnCl in a water/DMF mixture contains a polymeric chain structure similar to 2 and additionally one of the terminal SnPh₃ groups is coordinated to a DMF solvent molecule.     

Zustandsdiagramme von Alkalibromid-Lanthanoid(III)-bromid-Mischungen

Phase Diagrams of Alkali Bromide - Lanthanoid(III) Bromide Mixtures The phase diagrams of the systems KBr? PrBr₃ (NdBr₃, SmBr₃, GdBr₃, DyBr₃, ErBr₃, YbBr₃), RbBr? NdBr₃ (SmBr₃, GdBr₃, DyBr₃, ErBr₃, YbBr₃) and CsBr? PrBr₃ (NdBr₃, SmBr₃, GdBr₃, ErBr₃, YbBr₃) were determined by differential thermal analysis and differential scanning calorimetry. The compound M₃LnBr₆, whose stability increases with increasing size of the alkali cation resp. decreasing of the Ln³⁺ ion, was found in all investigated systems. Additionaly congruently melting compounds of the type MLn₂Br₇ were found in the system from PrBr₃ to DyBr₃ which are, however, peritectic in systems with smaller alkali cations. Another peritectic compound has the composition M₂LnBr₅, in case that the quotient ^rMe^+rX^?/^rLn³⁺ exceeds 3 this composition shifts to M₃Ln₂Br₉. The compounds M₃LnBr₆ have a transition with a transition temperature, which is concentration dependent. This May indicate that at the composition ?M₃LnBr₆”? in fact two compounds exist with slightly different composition, of which one is stable at higher the other at lower temperatures.     

Interactions in the SrS-Cu2S-Ln2S3 (Ln = Gd or Er) Systems and Phase-Formation Laws in the SrS-Cu2S-Ln2S3 (Ln = La-Lu) Systems

Structure solution has been carried out for newly synthesized compounds SrLnCuS₃ (Ln = Pr, Sm, Dy, or Er). These sulfides have orthorhombic structures of the following types: SrPrCuS₃ crystallizes in a BaLaCuS₃-type structure, space group Pnma; SrLnCuS₃ (Ln = Sm or Dy) crystallize in an Eu₂CuS₃-type structure, space group Pnma; and SrErCuS₃, in a KZrCuS₃-type structure, space group Cmcm. In studies of the SrS-Cu₂S-Ln₂S₃ (Ln = Gd or Er) systems, the following tie-lines at 1050 K were located: SrLnCuS₃-SrLn₂S₄, SrLnCuS₃-SrS, SrLnCuS₃-CuLnS₂, Cu₂S-SrLnCuS₃, SrLnCuS₃-solid solution C₀ of the Cu₂S-Gd₂S₃ (β-Cu₃ErS₃) system, and Ln₂S₃-SrLnCuS₃. In the series of the SrS-Cu₂S-Ln₂S₃ (Ln = La-Lu) systems, two tendencies are observed: monotony (decrease in the unit cell parameters and volumes and increase in the melting temperatures of SrLnCuS₃ compounds in the ranges La-Nd and Sm-Lu) and periodicity (two types of triangulation of the SrS-Cu₂S-Ln₂S₃ system, three structure types, and different space groups of SrLnCuS₃ compounds; jump in the melting temperatures of the SrLnCuS₃ compounds in the range Nd-Sm).     

Structural and energetic properties of RMX3-NH3 complexes

We have explored the structural and energetic properties of a series of RMX₃-NH₃ (M=Si, Ge; X=F, Cl; R=CH₃, C₆H₅) complexes using density functional theory and low-temperature infrared spectroscopy. In the minimum-energy structures, the NH₃ binds axially to the metal, opposite a halogen, while the organic group resides in an equatorial site. Remarkably, the primary mode of interaction in several of these systems seems to be hydrogen bonding (C-H--N) rather than a tetrel (N→M) interaction. This is particularly clear for the RMCl₃-NH₃ complexes, and analyses of the charge distributions of the acid fragment corroborate this assessment. We also identified a set of metastable geometries in which the ammonia binds opposite the organic substituent in an axial orientation. Acid fragment charge analyses also provide a clear rationale as to why these configurations are less stable than the minimum-energy structures. Matrix-isolation infrared spectra provide clear evidence for the occurrence of the minimum-energy form of CH₃SiCl₃–NH₃, but analogous results for CH₃GeCl₃–NH₃ are less conclusive. Computational scans of the M-N distance potentials for CH₃SiCl₃–NH₃ and CH₃GeCl₃–NH₃, both in the gas phase and bulk dielectric media, reveal a great deal of anharmonicity and a propensity for condensed-phase structural change.     

Novel Copolymers of 4-Fluorostyrene. 9. Some Ring-Disubstituted 2-Phenyl-1,1-dicyanoethylenes

Novel copolymers of trisubstituted ethylene monomers, ring-disubstituted 2-phenyl-1,1-dicyanoethylenes, RC₆H₃CH=C(CN)₂ (where R = 3-Br-4-CH₃O, 5-Br-2-CH₃O, 2-F-5-CH₃, 2-F-6-CH₃, 3-F-2-CH₃, 3-F-4-CH₃, 4-F-2-CH₃, 4-F-3-CH₃) and 4-fluorostyrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C-NMR. The order of relative reactivity (1/r ₁) for the monomers is 3-F-4-CH₃(1.64) > 5-Br-2-CH₃O (1.62) > 3-Br-4-CH₃O (1.36) > 4-F-2-CH₃(1.3) > 4-F-3-CH₃(1.26) > 3-F-2-CH₃(1.11) > 2-F-5-CH₃ (0.98) > 2-F-6-CH₃ (0.97). High T_g of the copolymers, in comparison with that of poly(4-fluorostyrene) indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 290–400°C range with residue, which then decomposed in 400–800°C range.     

Theoretical study on influence of ligand and solvent to CdS clusters

Based on the experimental zinc blende and wurtzite structures of CdS nanocrystals, five new CdS clusters (Cd₃S₃, (Cd₃S₃)₂, (Cd₃S₃)₃, Cd₄S₄ with C_2V, and Cd₄S₄ with T_D symmetry) are investigated via optimization of their original structures at B3LYP/Lanl2dz theoretical level. Through considering integration influence of solvent and ligand, our calculated Raman and absorption spectra can be consistent with the reported experimental results. First, our calculated Raman peaks of Cd₃S₃, Cd₄S₄ (T_D), (Cd₃S₃)₂, and (Cd₃S₃)₃ are within the range of 260–290 cm^?1, which is also reported by experiment. Subsequently, for deep researching five clusters, the absorption spectra of them are calculated using time‐dependent DFT method. The wavelengths of the absorption peaks, which is calculated in solvent, increase in the order Cd₃S₃, Cd₄S₄ (T_D), (Cd₃S₃)₂, and (Cd₃S₃)₃. Moreover, the wavelengths of absorption peaks shift to blue in solvent, compared with those without solvent. Furthermore, our clusters are smaller than the size of the smallest CdS nanocrystals, the calculated absorption spectra of five clusters in solvent show obvious blue shift than the wavelengths of absorption spectra of reported CdS nanocrystals. This is induced by the quantum size effect. Besides, we further investigated the influence of ligands to CdS unit in aqueous condition. Through structures and characters analysis of S? Cd? SR, we discovered that ligands took important role during the formation of CdS nanocrystals in aqueous synthesis. Calculated results of spectra, bond length, and Wiberg bond index (WBI) values show that different ligands have similar influence on CdS unit. Moreover, using WBI values, we also confirm that Cd atom has stronger interaction with S in nanocrystals than that with S atom in ligand. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Synthese und Eigenschaften teilsilylierter Tri- und Tetraphosphane. Reaktionen lithiierter Diphosphane mit Chlorphosphanen

Synthesis and Properties of Partially Silylated Tri- and Tetraphosphanes. Reaction of Lithiated Diphosphanes with Chlorophosphanes The reactions of Li(Me₃Si)P? P(SiMe₃)(CMe₃) 1 , Li(Me₃Si)P? P(CMe₃)₂ 2 , and Li(Me₃C)P? P(SiMe₃)(CMe₃) 3 with the chlorophosphanes P(SiMe₃)(CMe₃)Cl, P(CMe₃)₂Cl, or P(CMe₃)Cl₂ generate the triphosphanes [(Me₃C)(Me₃Si)P]₂P(SiMe₃) 4 , (Me₃C)(Me₃Si)P? P(SiMe₃)? P(CMe₃)₂ 6 , [(Me₃C)₂P]₂P(SiMe₃) 7 , and (Me₃C)(Me₃Si)P? P(SiMe₃)? P(CMe₃)Cl 8 . The triphosphane (Me₃C)₂P? P(SiMe₃)? P(SiMe₃)₂ 5 is not obtainable as easily. The access to 5 starts by reacting PCl₃ with P(SiMe₃)(CMe₃)₂, forming (Me₃C)₂ P? PCl₂, which then with LiP(SiMe₃)₂ gives (Me₃C)₂ P? P(Cl)? P(SiMe₃)₂ 11 . Treating 11 with LiCMe₃ generates (Me₃C)₂P? P(H)? P(SiMe₃)₂ 16 , which can be lithiated by LiBu to give (Me₃C)₂P? P(Li)? P(SiMe₃)₂ 13 and after reacting with Me₃SiCl, finally yields 5 . 8 is stable at ?70°C and undergoes cyclization to P₃(SiMe₃)(CMe₃)₂ in the course of warming to ambient temperature, while Me₃SiCl is split off. 7 , reacting with MeOH, forms [(Me₃C)₂P]₂PH. (Me₃C)₂P? P(Li)? P(SiMe₃)₂ 18 , which can be obtained by the reaction of 5 with LiBu, decomposes forming (Me₃C)₂P? P(Li)(SiMe₃), P(SiMe₃)₃, and LiP(SiMe₃)₂, in contrast to either (Me₃C)₂P? P(Li)? P(SiMe₃)(CMe₃) 19 or [(Me₃C)₂P]₂PLi, which are stable in ether solutions. The Li phosphides 1 , 2 , and 3 with BrH₂C? CH₂Br form the n-tetraphosphanes (Me₃C)(Me₃Si)P? [P(SiMe₃)]₂? P(SiMe₃)(CMe₃) 23 , (Me₃C)₂P? [P(SiMe₃)]₂? P(CMe₃)₂ 24 , and (Me₃C)(Me₃Si)P? [P(CMe₃)]₂? P(SiMe₃)(CMe₃) 25 , respectively. Li(Me₃Si)P? P(SiMe₃)₂, likewise, generates (Me₃Si)₂P? [P(SiMe₃)]₂? P(SiMe₃)₂ 26 . Just as the n-triphosphanes 4 , 5 , 6 , and 7 , the n-tetraphosphanes 23 , 24 , and 25 can be isolated as crystalline compounds. 23 , treated with LiBu, does nor form any stable n-tetraphosphides, whereas 24 yields (Me₃C)₂P? P(Li)? P(SiMe₃)? P(CMe₃)₂, that is stable in ethers. With MeOH, 24 , forms crystals of (Me₃C)₂P? P(H)? P(SiMe₃)? P(CMe₃)₂.     

Reactions of Beryllium Halides in Liquid Ammonia: The Tetraammineberyllium Cation [Be(NH3)4]2+, its Hydrolysis Products,and the Action of Be2+ as a Fluoride‐Ion Acceptor

The first structural characterization of the text‐book tetraammineberyllium(II) cation [Be(NH₃)₄]²⁺, obtained in the compounds [Be(NH₃)₄]₂Cl₄ ? 17NH₃ and [Be(NH₃)₄]Cl₂, is reported. Through NMR spectroscopic and quantum chemical studies, its hydrolysis products in liquid ammonia were identified. These are the dinuclear [Be₂(μ‐OH)(NH₃)₆]³⁺ and the cyclic [Be₂(μ‐OH)₂(NH₃)₄]²⁺ and [Be₃(μ‐OH)₃(NH₃)₆]³⁺ cations. The latter species was isolated as the compound [Be₃(μ‐OH)₃(NH₃)₆]Cl₃ ? 7NH₃. NMR analysis of solutions of BeF₂ in liquid ammonia showed that the [BeF₂(NH₃)₂] molecule was the only dissolved species. It acts as a strong fluoride‐ion acceptor and forms the [BeF₃(NH₃)]^? anion in the compound [N₂H₇][BeF₃(NH₃)]. The compounds presented herein were characterized by single‐crystal X‐ray structure analysis, ⁹Be, ¹⁷O, and ¹⁹F NMR, IR, and Raman spectroscopy, deuteration studies, and quantum chemical calculations. The extension of beryllium chemistry to the ammine system shows similarities but also decisive differences to the aquo system.     

The Molybdenum(V) and Tungsten(VI) Oxoazides [MoO(N3)3], [MoO(N3)3⋅2 CH3CN], [(bipy)MoO(N3)3], [MoO(N3)5]2−, [WO(N3)4], and [WO(N3)4⋅CH3CN]

A series of novel molybdenum(V) and tungsten(VI) oxoazides was prepared starting from [MOF₄] (M=Mo, W) and Me₃SiN₃. While [WO(N₃)₄] was formed through fluoride–azide exchange in the reaction of Me₃SiN₃ with WOF₄ in SO₂ solution, the reaction with MoOF₄ resulted in a reduction of Mo^VI to Mo^V and formation of [MoO(N₃)₃]. Carried out in acetonitrile solution, these reactions resulted in the isolation of the corresponding adducts [MoO(N₃)₃?2 CH₃CN] and [WO(N₃)₄?CH₃CN]. Subsequent reactions of [MoO(N₃)₃] with 2,2′‐bipyridine and [PPh₄][N₃] resulted in the formation and isolation of [(bipy)MoO(N₃)₃] and [PPh₄]₂[MoO(N₃)₅], respectively. Most molybdenum(V) and tungsten(VI) oxoazides were fully characterized by their vibrational spectra, impact, friction and thermal sensitivity data and, in the case of [WO(N₃)₄?CH₃CN], [(bipy)MoO(N₃)₃], and [PPh₄]₂[MoO(N₃)₅], by their X‐ray crystal structures.     

K3SbSe3, Rb3SbSe3 und Cs3SbSe3 – Synthese und Kristallstruktur

K₃SbSe₃, Rb₃SbSe₃, and Cs₃SbSe₃ – Synthesis and Crystal Structure The compounds K₃SbSe₃, Rb₃SbSe₃ and Cs₃SbSe₃ were synthesized by heating mixtures of Sb₂O₃ and an alkalicarbonate in a stream of hydrogen saturated by selenium in a temperature range between 750 °C and 800 °C. The compounds crystallize isostructural with Na₃AsS₃. A comparison of atomic distances and bond angles with those of the isostructural arsenic and bismuth compounds shows the effect of lone pairs.     

单氢钌配合物与水和2,2,2-三氟乙醇的作用机理

利用原位¹H和³¹P NMR对单氢钌配合物TpRu(PPh₃)(CH₃CN)H [Tp＝hydrotris(pyrazolyl)borate]与H₂O和酸性HOCH₂CF₃的反应进行了研究, 结果显示相应的反应产物分别是TpRu(PPh₃)(CH₃CN)(OH) 和TpRu(PPh₃)(CH₃CN)(OCH₂CF₃). 观察到反应过程中Ru-H…HOH和Ru-H…HOCH₂CF₃分子间的氢键作用. 提出了生成TpRu(PPh₃)(CH₃CN)(OH)和TpRu(PPh₃)(CH₃CN)(OCH₂CF₃)的不同作用机理. 在水存在下, TpRu(PPh₃)(CH₃CN)H 与H₂O反应, 经过中间体TpRu(PPh₃)(H₂O)H和TpRu(PPh₃)(OH)(η²-H₂)生成产物TpRu(PPh₃)(CH₃CN)(OH). 而TpRu(PPh₃)(CH₃CN)H与酸性HOCH₂CF₃反应时, 单氢配体被质子化形成中间体[TpRu(PPh₃)(CH₃CN)- (η²-H₂)](OCH₂CF₃), 进而转变成产物TpRu(PPh₃)(CH₃CN)(OCH₂CF₃). TpRu(PPh₃)(CH₃CN)(OCH₂CF₃)与H₂作用, 经中间体TpRu(PPh₃)(HOCH₂CF₃)H生成TpRu(PPh₃)(η²-H₂)H.     

Novel Copolymers of 4-Fluorostyrene. 8. Some Ring-Trisubstituted 2-Phenyl-1,1-dicyanoethylenes

Novel copolymers of trisubstituted ethylene monomers, ring-substituted 2-phenyl-1,1-dicyanoethylenes, RC₆H₂CH=C(CN)₂ (where R is 2,4-(CH₃O)₂-3-CH₃, 2,3,4-(CH₃O)₃, 2,4,5-(CH₃O)₃, 2,4,6-(CH₃O)₃, 3,4,5-(CH₃O)₃, 6-Br-3,4-(CH₃O)₂), 2,3,5-Cl₃, 2,3,6-Cl₃ and 4-fluorostyrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C-NMR. The order of relative reactivity (1/r ₁) for the monomers is 3,4,5-(CH₃O)₃(10.6) > 2,4,6-(CH₃O)₃(9.3) > 2,4,5-(CH₃O)₃ (5.4) > 2,3,4-(CH₃O)₃ (4.4) > 6-Br-3,4-(CH₃O)₂ (3.2) > 2,3,5-Cl₃ (1.5) > 2,3,6-Cl₃ (1.0) > 2,4-(CH₃O)₂-3-CH₃ (0.7). High T _g of the copolymers, in comparison with that of poly(4-fluorostyrene) indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–400°C range with residue, which then decomposed in the 400–800°C range.     

Studies on the formation of manganese molybdate

The reaction of MoO₃ with various oxides of manganese (MnO, Mn₂O₃, Mn₃O₄ and MnO₂) and with MnCO₃ has been studied in air and nitrogen atmospheres employing DTA, TG and X-ray diffraction methods, with a view to elucidating the conditions for the formation of MnMoO₄. Thermal decomposition of MnCO₃ has also been studied in air and nitrogen atmospheres to help understand the mechanism of the reaction between MnCO₃ and MoO₃. The studies reveal that, whereas MnO, Mn₂O₃ and MnO₂ react smoothly with MoO₃ to form MnMoO₄, Mn₃O₄ does not react with MoO₃ in the temperature range investigated (48O–6OO°C). An equimolar mixture of MnCO₃ and MoO₃ reacts in air to yield MnMoO₄, while only a mixture of Mn₃O₄ and MoO₃ remains as final product when the same reaction is carried out in nitrogen. Marker studies reveal that manganese ions are the main diffusing species in the reaction between MoO₃ and manganese oxides that result in MnMoO₄.