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

New 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: Au-4 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 a parts per thousand 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 mu(B)/Eu atom, near to the free ion value of 7.94 mu(B) for Eu2+ and orders ferromagnetically at T (C) = 16.3(5) K. Eu-151 Mossbauer 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.