121Sb Mössbauer spectra of alkali metal antimonides M3Sb (M3 = Na3, K3, Na2K, Rb3)

¹²¹Sb Mössbauer spectra for M₃Sb (M₃ = Na₃, K₃, Na₂K, Rb₃) were measured at 12 K. The values of isomer shift (d) and quadrupole coupling constant suggest that the valence state of antimony in M₃Sb is –3. The d values increase in the order Rb₃Sb<K₃Sb<Na₃Sb<Na₂KSb. The differences in d values are discussed by examining M–Sb distances and bond valence for M–Sb interactions. Some covalent interactions between alkali metal atoms and antimony atom are suggested.     

Synthesis of 3H-labeled Efomycine M

For in-depth characterization as a putative pan-selectin antagonist 3H-labeled Efomycine M was synthesized starting from the natural product derived from Elaiophyline.     

Zintl-Verbindungen mit Gold: M3AuSn4 mit M = K,Rb, Cs und M3AuPb4 mit M = Rb,Cs

Zintl-Compounds with Gold: M₃AuSn₄ with M = K, Rb, Cs and M₃AuPb₄ with M = Rb, Cs Silver coloured, brittle single crystals of the compounds M₃AuSn₄ with M = K, Rb, Cs and M₃AuPb₄ with M = Rb, Cs were synthesized by reactions of alkali metal azides (MN₃) with gold sponge and tin (lead) powder at T = 923 K. The structures of the isotypic compounds (space group Pmmn, Z = 2) were determined from X-ray single-crystal diffractometry data (see ‘‘Inhaltsübersicht”︁”︁). The Zintl-compounds M₃AuE(14)₄ with E(14) = Sn, Pb contain [AuE(14)₄]-chains with P₄-analogous E(14)₄-tetrahedra which are connected by μ₂-bridging gold atoms.     

(1,3,5-C3P3H3)M与(1,3,5-C3P3H3)2M (M=Ti,V, Cr)配合物的结构与芳香性

运用密度泛函理论研究了(1,3,5-C3P3H3)M和(1,3,5-C3P3H3)2M (M=Ti,V,Cr)的结构、键合能以及芳香性.结果表明:低自旋的(1,3,5-C3P3H3)M和(1,3,5-C3P3H3)2M基态结构分别具有C3v和D3h对称性.金属与配体间为共价作用,二者之间存在σ、π和σ三种成键方式.V的三明治配合物的解离方式与Ti和Cr的三明治配合物不同,前者为分步解离,后两者则为一步解离.其中(1,3,5-C3P3H3)2Cr(D3h)的第一解离能最大,配合物最稳定.这些三明治和半三明治配合物都具有中心芳香性、内芳香性和外芳香性,且中心芳香性均大于自由配体(1,3,5-C3P3H3)的中心芳香性,芳香性主要贡献来源于π键和金属原子的孤对电子.内芳香性按照Ti、V、Cr的顺序依次增大,且内芳香性明显要大于外芳香性.高自旋的半三明治(1,3,5-C3P3H3)Ti(C3,5A1)与单重态(1,3,5-C3P3H3)Ti (C3v,1A1)相比,配体的变形性增大,稳定性增加,且C平面中心芳香性和内芳香性均增大,但P平面的中心芳香性却降低.     

Zur Kristallstruktur von Cu2M(BO3)O2 (M = Fe3+, Ga3+)

The Crystal Structure of Cu₂M(BO₃)O₂ (M = Fe³⁺, Ga³⁺) Single Crystals of the compounds Cu₂M(BO₃)O₂ (M = Fe³⁺ (I), Ga³⁺ (II)) were obtained by a B₂O₃ flux-technique. They crystallize in a monoclinic distorted variant of a Ludwigite structure with a partly ordered metal distribution. X-ray investigations on single crystals led to the space group C–P2₁/c (No. 14); I: a = 3.108(1); b = 12.003(1); c = 9.459(3) Å; b? = 96.66(3)°; Z = 4 and II: a = 3.1146(2); b = 11.921(3); c = 9.477(2) Å; b? = 97.91(2)°; Z = 4. All metal-sites are distorted octahedraly coordinated by oxygen-ions. The structure contains isolated planar BO₃-units and oxygen which is not coordinated to boron.     

(CH~3)~3M/PH~3(M=Ga,In)体系的密度泛函研究

用密度泛函理论方法对Me~3M/PH~3(Me=CH~3,M=Ga,In)体系及相关的一些分子进行了计算,得到优化几何构型、振动基频、电荷分布等参数和可能发生的化学反应的能量。为了比较,对Me~3Ga/NH~3体系也做了相应的研究。计算结果表明反应中间体Me~3M·YH~3(Y=N,P)具有稳定的结构,其生成反应是放热的。Me~3M·YH~3中的M－Y键比较弱,但当它们通过一个放热的分子内反应分解为Me~2MYH~2和CH~4后M－Y键大为增强。根据计算结果讨论了Me~3M/YH~3体系可能的热分解途径。由于Me~3M·YH~3单分子分解反应活化能比Me~3M中的M－C键直接均裂分解所需的能量要低得多,在有YH~3存在的情况下,Me~3M的热分解最有可能是首先形成Me~3M·YH~3及Me~2MYH~2中间体,然后进一步分解。用这一机理可以解释现有的实验事实。     

选择性M3受体拮抗剂的研究进展

M3受体是毒蕈碱型乙酰胆碱受体的亚型之一,在人体内分布广泛。选择性M3受体拮抗剂可以竞争性地与M3受体结合,主要用于膀胱过度活动症(OAB)、慢性阻塞性肺病(COPD)和肠道易激综合症(IBS)等疾病的治疗。与非选择性拮抗剂相比,选择性M3受体拮抗剂对中枢神经以及心脏的副作用大大降低。本文对已上市及处在不同研究阶段的选择性M3受体拮抗剂进行了综述。     

Verbindungen vom TypT 5 M 3 X

Zusammenfassung Legierungen mit AnsatzTMX=531 werden durch Sintern hergestellt, um die Verbreitung des aufgefüllten Mn₅Si₃-Typs zu ermitteln. Von etwa 80 bisher daraufhin noch nicht geprüften Dreistoffen werden lediglich die D 8₈-Phasen Nb₅Ga₃C _x , Nb₅Ga₃N _x , Nb₅Ge₃C _x , Nb₅Ge₃N _x , Ta₅Ga₃C _x , Ta₅Ga₃N _x , Ta₅Ge₃C _x , Ta₅Ge₃N _x und Mo₅Ge₃C _x gefunden bzw. bestätigt. T=Übergangsmetall,M=Ga, Ge,X=Kohlenstoff, Stickstoff.     

M+M3+2As(HAsO4)6 and α‐ and β‐M+M3+(HAsO4)2 (M+M3+ = RbAl or CsFe): six new compounds crystallizing in three closely related structure types

The crystal structures of hydrothermally synthesized (T = 493 K, 7–9 d) rubidium aluminium bis[hydrogen arsenate(V)], RbAl(HAsO₄)₂, caesium iron bis[hydrogen arsenate(V)], CsFe(HAsO₄)₂, rubidium dialuminium arsenic(V) hexakis[hydrogen arsenate(V)], RbAl₂As(HAsO₄)₆, and caesium diiron arsenic(V) hexakis[hydrogen arsenate(V)], CsFe₂As(HAsO₄)₆, were solved by single‐crystal X‐ray diffraction. The four compounds with the general formula M⁺M³⁺(HAsO₄)₂ adopt the RbFe(HPO₄)₂ structure type (Rc) and a closely related new structure type, which is characterized by a different stacking order of the building units, leading to noncentrosymmetric space‐group symmetry R32. The second new structure type, with the general formula M⁺M³⁺₂As(HAsO₄)₆ (Rc), is also a modification of the RbFe(HPO₄)₂ structure type, in which one third of the M³⁺O₆ octahedra are replaced by AsO₆ octahedra, and two thirds of the voids in the structure, which are usually filled by M⁺ cations, remain empty to achieve charge balance.     

Präparation und röntgenographische Charakterisierung der Verbindungen Ca3M2Ga2 (M = Pd,Pt) und Ca3M2Ga3 (M = Rh,Ir)

Preparation and Crystal Structures of the Compounds Ca₃Pd₂Ga₂, Ca₃Pt₂Ga₂, Ca₃Rh₂Ga₃, and Ca₃Ir₂Ga₃ The new compounds Ca₃Pd₂Ga₂, Ca₃Pt₂Ga₂, Ca₃Rh₂Ga₃, and Ca₃Ir₂Ga₃ were prepared by heating appropriate mixtures of the elements under an Argon-atmosphere. The results of the structure analysis of single crystals by means of X-ray diffraction are given in the section “Inhaltsübersicht”. Ca₃Pd₂Ga₂ and Ca₃Pt₂Ga₂ are isotypic and form the Y₃Rh₂Si₂ type structure (Pbcm), where the platinium metals have a trigonal environment consisting of Ga-atoms. The isotypic compounds Ca₃Rh₂Ga₃ and Ca₃Ir₂Ga₃ (Pbcm) form a new type of structure, which is related to the Y₃Rh₂Si₂ type with a distorted tetrahedral surrounding of Ga-atoms for Rh (resp. Ir).     

Darstellung und Eigenschaften von Komplexen des Typs cis-(RCN)3M(CO)3 (M = Cr,M, W)

Metal complexes of the type cis-(RCN)₃M(CO)₃ (M = Cr, Mo, W) have been prepared by different methods starting with M(CO)₆ or, more conveniently, with substituted derivatives of the metal hexacarbonyls. Infrared spectroscopic studies indicate that the strength of the nitrile-to-metal bond in cis-(RCN)₃M(CO)₃ is only sligthly influenced by the R group. The chromium compounds cis-(RCN)₃Cr(CO)₃ may be used as starting materials for the preparation of hexaalkylborazine-chromium-tricarbonyls.     

Synthesis of indium alkali-earth double borates M3In(BO3)3

Double borates of composition M₃In(BO₃)₃ (M = Ba, Sr) were prepared by solid-phase reactions and studied using X-ray diffraction powder analysis and IR spectroscopy. The compounds were shown to be isostructural and to crystallize in trigonal space group , Z = 6. Unit cell parameters were refined for both phases.     

Der Aufbau der Silizide M5Si3

Zusammenfassung Die noch unaufgeklärte Struktur der zweiten Modifikation von Nb₅Si₃ bzw. Ta₅Si₃ wurde bestimmt. Diese Phasen kristallisieren im Cr₅B₃-Typ, dessen Parameter für die 8 (h) Lage korrigiert wurde. Eine Übersicht über die im Mittelgebiet (33 bis 40 At.–bis% Si) auftretenden Silizide der Übergangsmetalle (4a-, 5a-, 6a-Gruppe) wiwd gegeben und der genetische Zusammenhang der hier bestehenden Gitter erörtert.Mit 1 AbbildungM bedeutet Metall.     

Theoretical exploration on the vibrational and mechanical properties of M3C2/M3C2T2 MXenes

MXenes have attracted intensive attention in chemistry and material science for their special structures and properties. In order to understand the basic physical properties of the M₃C₂/M₃C₂T₂ (MSc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W; TF, O, OH) MXenes, first-principles calculations are carried out to investigate the structural, vibrational, and mechanical properties in this work. Both the metal atoms and surface groups can significantly influence the configurations or mechanical behaviors of the MXenes. The dehydrogenation tendency is calculated to evaluate the possible forms of the M₃C₂(OH)₂ toward M₃C₂O₂. The work functions of MXenes functionalized by different groups are compared, and the lower work functions for the  OH functionalized ones, which can be as low as 1.358 eV for the Sc₃C₂(OH)₂, suggest potential good performance in electron emission. In addition, the stability, mechanical properties, and the Raman and infrared (IR) activity modes of the MXenes are reported. Generally, functionalized MXenes would present smaller lattice parameters, lower free energies, and stronger mechanical strength compared to their counterparts. The data obtained may provide important theoretical ground for the investigations of the applications of MXenes.     

Univalent gallium and indium phosphane complexes: from pyramidal M(PPh3)3(+) to carbene-analogous bent M(PtBu3)2(+) (M=Ga, In) complexes

In a new oxidative route, Ag(+)[Al(OR(F))(4)](-) (R(F)=C(CF(3))(3)) and metallic indium were sonicated in aromatic solvents, such as fluorobenzene (PhF), to give a precipitate of silver metal and highly soluble [In(PhF)(n)](+) salts (n=2, 3) with the weakly coordinating [Al(OR(F))(4)](-) anion in quantitative yield. The In(+) salt and the known analogous Ga(+)[Al(OR(F))(4)](-) were used to synthesize a series of homoleptic PR(3) phosphane complexes [M(PR(3))(n)](+), that is, the weakly PPh(3)-bridged [(Ph(3)P)(3)In-(PPh(3))-In(PPh(3))(3)](2+) that essentially contains two independent [In(PPh(3))(3)](+) cations or, with increasing bulk of the phosphane, the carbene-analogous [M(PtBu(3))(2)](+) (M=Ga, In) cations. The M(I)-P distances are 27 to 29 pm longer for indium, and thus considerably longer than the difference between their tabulated radii (18 pm). The structure, formation, and frontier orbitals of these complexes were investigated by calculations at the BP86/SV(P), B3LYP/def2-TZVPP, MP2/def2-TZVPP, and SCS-MP2/def2-TZVPP levels.     

The double salts M3RE(SO4)3 (M=K,Rb) with framework structures

The crystal structures of K₃Er(SO₄)₃ [space group Pc, a=9.222(2), b=14.688(1), c=9.008(1) Å, =110.72(2)^o, Z=4, R=0.59] and of Rb₃Tm(SO₄)₃ [space group Cc, a=10.649(2), b=15.149(3), c=9.320(2) Å, =124.49(1)^o, Z=4, R=0.043] have been studied (CAD-4 diffractometer, Mo radiation). It has been shown that the compounds K₃RE(SO₄)₃ (RE=Nd–Er) and Rb₃RE(SO₄)₃ (RE=Tm–Lu), which crystallize in accordance with these structural types, form a family of framework structures with a single basis. The relationship between their structure and the structure of the rhombohedral compounds M₃M^III(SO₄)₃ (M^III=Al, Ga, In) and Cs₃Yb(SO₄)₃ has been examined.Scientific-Research Institute of Chemical Reagents and Ultrapure Chemical Substances. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 110–115, March–April, 1991.