EuPtSn 2 – A Stannide with Sn 2 Dumbbells in a Three‐dimensional [PtSn 2 ] 2– Polyanion

EuPtSn 2 was obtained by melting of the elements in a sealed tantalum ampoule followed by an annealing sequence for crystal growth. The EuPtSn 2 sample was studied through its Guinier powder pattern and the structure was refined from single‐crystal X‐ray diffractometer data: CeRhSn 2 type, Cmcm, a = 472.05(3), b = 1724.19(12), c = 957.36(7) pm, wR 2 = 0.0388, 879 F 2 values and 30 variables. The platinum and tin atoms build up a three‐dimensional [PtSn 2 ] 2– polyanionic network which consists of distorted PtSn 5 square pyramids (265–278 pm Pt–Sn) and Sn 2 dumbbells with 281 and 299 pm Sn–Sn distances. The structural relationship with DyRhGe 2 and Ce 3 Pt 4 Ge 6 is discussed. EuPtSn 2 shows Curie–Weiss behavior with an experimental magnetic moment of 7.78(1) μ B / Eu, indicating stable divalent europium. This is corroborated by 151 Eu Mössbauer spectroscopy. Antiferromagnetic ordering is detected below 3.4 K. Specific heat measurements confirm the magnetic ordering and indicate a second phase transition through a clear λ‐type signal at 7.3 K which might be associated with a structural distortion.