Linear infinite cadmium chains in CaAu4Cd2 and other intermetallics with YbMo2Al4-type structure

Abstract

International audienceNew YbMo2Al4-type cadmium compounds CaAu4Cd2, SrAu4Cd2, and EuAu4Cd2 were synthesized from the elements in sealed tantalum tubes. The structures of CaAu4Cd2 (I4/mmm, a = 710.7(1), c = 550.2(3) pm, wR2 = 0.026, 168 F 2 values, 10 variables) and EuAu4.80Cd1.20 (a = 716.6(1), c = 545.9(1) pm, wR2 = 0.024, 167 F 2 values, 11 variables) were refined from X-ray single-crystal diffractometry data. The gold and cadmium atoms show different substructures: Au4 squares (279 pm Au-Au in CaAu4Cd2) and cadmium chains (275 pm Cd-Cd in CaAu4Cd2). EuAu4Cd2 forms a solid solution EuAu4+x Cd2−x up to x ≈ 1, where almost every other cadmium atom within the chains is substituted by gold. Chemical bonding analyses on CaAu4Cd2 shows almost complete charge transfer from calcium to the [Au4Cd2] network. Bader charge analysis classifies CaAu4Cd2 as an auride. EuAu4Cd2 shows Curie-Weiss behavior above 25 K with an experimental magnetic moment of 7.86 μB/Eu atom, near to the free ion value of 7.94 μB for Eu2+ and orders ferromagnetically at T C = 16.3(5) K. 151Eu Mössbauer spectra show a single signal at an isomer shift of about −10 mm/s, compatible with divalent europium. At 5 K, and therefore clearly below T C, magnetic hyperfine splitting is observed

Tethering Metal Ions to Photocatalyst Particulate Surfaces by Bifunctional Molecular Linkers for Efficient Hydrogen Evolution

“…For the cerium compound all sites were fully occupied within two standard deviations and in the final cycles the ideal occupancies were assumed again. Similar to EuAu 4.79 Cd 1.21 16 and SrAu 4.76 In 1.24 ,19 also the zinc site of the calcium compound showed mixed occupancy with gold. In the final least‐squares cycles the mixing was refined as a least‐squares variable, leading to the composition CaAu 4.08(1) Zn 1.92(1) for the investigated crystal.…”

“…Either the compounds are p ‐element‐rich (Al, Ga) and the transition metal atoms build up linear chains (4 d site) or one observes the opposite site occupancies. This is the case for the A Au 4 Zn 2 ( A = Ca, Ce, Pr, Nd) compounds reported herein as well as for SrAu 4.76 In 1.24 19 and the cadmium intermetallic compounds CaAu 4 Cd 2 , SrAu 4 Cd 2 , and EuAu 4 Cd 2 16. We also tried synthesis attempts with lanthanum and samarium in order to test the existence range for this series of compounds.…”

Dimorphic EuCu5Cd

“…These pairs are surrounded by the copper matrix. Infinite linear cadmium chains with shorter CdCd distances of 273 pm have recently been observed in the solid solution EuAu 4+x Cd 2−x , in CaAu 4 Cd 2 and in SrAu 4 Cd 2 [9].…”

Electronic Structure and Bonding in YTi2Ga4 – A Gallide with Linear Titanium Chains and Four-bonded Gallium Atoms

“…In continuation of our studies on the structural data and chemical bonding behavior of YbMo 2 Al 4 type intermetallics [7,8] we have now investigated the electronic structure of YTi 2 Ga 4 [4]. The purpose of this work is to present further analyses of the electronic band structure and the chemical bonding using computational methods built within the wellestablished quantum-theoretical density functional theory (DFT) framework [12,13].…”

“…GdMo 2 Al 4 and ErMo 2 Al 4 are isotypic with the ytterbium compound. This structure type has also been observed for a variety of gallides RTi 2 Ga 4 (R = Zr, Sc, Y, Tb, Dy, Ho, Er, Tm, Lu) [2 -6] and RV 2 Ga 4 (R = Sc, Zr, Er, Hf) [2], the indide SrAu 4.76 In 1.24 [7], the cadmium compounds CaAu 4 Cd 2 , SrAu 4 Cd 2 , and EuAu 4 Cd 2 [8] as well as the solid solutions YbCu 5.1 Al 0.9 [9], YbCu 5.12 Al 0.88 [10] and CeCu 4.7 Mn 1.3 [11]. From the point of view of chemical bonding, the coloring (i. e. exchanging the transition metal and p-element positions) of the polyanionic network is an interesting question, regarding e. g. YbMo 2 Al 4 vs. SrAu 4 Cd 2 ; aluminides vs. aurides etc.…”