Different Ways To Distort a Tetracapped Tetrahedron on Route to Forming an E4M4 Cubane: The Case of [E4(Pd(PPh2Me)2)4][Ph2EX2]2 (E = Sb, X = Cl; E = Bi, X = Br)
摘要:
Tetrakis(diphenylmethylphosphine)palladium reacts with diphenylantimony chloride or diphenyl-bismuth bromide to give [E-4(PdL2)(4)][Ph2EX2](2) (L = PPh2Me, 1: E = Sb, X = Cl; 2: E = Pi, X = Br) which have been characterized spectroscopically and by single-crystal X-ray diffraction for [Sb-4(PdL2)(4)][Ph2SbCl2](2). 0.5THF and [Bi-4(PdL2)(4)][Ph2BiBr2](2). These compounds are electron-rich based on electron counting formalisms. The additional cluster electrons can be rationalized by the ability of group 15 elements to show hypervalency, particularly those elements such as Sb and Pi which show more metal character. The electronic structure of the compounds and of related species has been examined by EHT and DFT calculations. Relationships to other cubane-derived structures are derived, and the stability of structurally related M4E4 hypothetical clusters is discussed. Compounds 1 and 2 decompose thermally to give Bi2Pd and SbPd.
systematically examined by the magnetic susceptibility and resistivity measurements. Both alloysystems have shown bulk superconductivity and metallic conductivity in normal state. Furthermore, the superconducting onset temperature (Tc) gradually decreased with higher Pb content for both systems. The Tc dropped from 3.7 K for BiPd to 2.7 K for Bi0.8Pb0.2Pd, whereas the Tc dropped from 5.3 K for Bi2Pd to
摘要 采用简便的固相反应法合成了一系列掺铅铋基合金α-Bi1-xPbxPd (0 ≤ x ≤ 0.5) 和β-Bi2-xPbxPd (0 ≤ x ≤ 0.6)。粉末X射线衍射证实,Pb掺杂后样品的晶体结构保持不变,随着Pb含量的增加,晶胞体积减小。已通过磁化率和电阻率测量系统地研究了 Pb 掺杂效应对 BiPd 和 Bi2Pd 合金超导性的影响。两种合金系统在正常状态下都显示出体超导性和金属导电性。此外,两种系统的超导起始温度(Tc)随着铅含量的增加而逐渐降低。Tc 从 BiPd 的 3.7 K 下降到 Bi0.8Pb0.2Pd 的 2.7 K,而 Bi2Pd 的 Tc 从 5.3 K 下降到 Bi1.5Pb0.5Pd 的 2.4 K。
Low-temperature thermal expansion of the topological material candidates <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e853" altimg="si70.svg"><mml:mi>β</mml:mi></mml:math>-PtBi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e858" altimg="si71.svg"><mml:msub><mml:mrow /><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e866" altimg="si70.svg"><mml:mi>β</mml:mi></mml:math>-PdBi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e872" altimg="si71.svg"><mml:msub><mml:mrow /><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>
We report on the low-temperature (T< 120 K) thermalexpansion of the bismuth-based topological semimetal β-PtBi2 and topological superconductor β-PdBi2 candidates. The linear thermal-expansion coefficient of tetragonal β-PdBi2 shows a pronounced anisotropy between the a- and c-axis while the volume thermal-expansion coefficient αV (β-PdBi2) is considerable larger than αV (β-PtBi2). The coefficient
Different Ways To Distort a Tetracapped Tetrahedron on Route to Forming an E<sub>4</sub>M<sub>4</sub> Cubane: The Case of [E<sub>4</sub>(Pd(PPh<sub>2</sub>Me)<sub>2</sub>)<sub>4</sub>][Ph<sub>2</sub>EX<sub>2</sub>]<sub>2</sub> (E = Sb, X = Cl; E = Bi, X = Br)
作者:Joseph L. Stark、Brian Harms、Ilse Guzman-Jimenez、Kenton H. Whitmire、Régis Gautier、Jean-François Halet、Jean-Yves Saillard
DOI:10.1021/ja982902u
日期:1999.5.1
Tetrakis(diphenylmethylphosphine)palladium reacts with diphenylantimony chloride or diphenyl-bismuth bromide to give [E-4(PdL2)(4)][Ph2EX2](2) (L = PPh2Me, 1: E = Sb, X = Cl; 2: E = Pi, X = Br) which have been characterized spectroscopically and by single-crystal X-ray diffraction for [Sb-4(PdL2)(4)][Ph2SbCl2](2). 0.5THF and [Bi-4(PdL2)(4)][Ph2BiBr2](2). These compounds are electron-rich based on electron counting formalisms. The additional cluster electrons can be rationalized by the ability of group 15 elements to show hypervalency, particularly those elements such as Sb and Pi which show more metal character. The electronic structure of the compounds and of related species has been examined by EHT and DFT calculations. Relationships to other cubane-derived structures are derived, and the stability of structurally related M4E4 hypothetical clusters is discussed. Compounds 1 and 2 decompose thermally to give Bi2Pd and SbPd.