Ternary platinides Sr4In13Pt9 and Eu5In9Pt7

Sr4In13Pt9 and Eu5In9Pt7 were synthesized by induction melting of the pure elements in glassy carbon crucibles. Both compounds were characterized through their X-ray powder patterns and the structures were refined from X-ray single crystal diffractometer data: Ho4Ir13Ge9 type, Pmmn, a = 439.17(5) pm, b = 1232.2(2) pm, c = 2135.3(3) pm, wR2 = 0.0550, 3598 F2 values, 88 variables for Sr4In13Pt9 and Sc5Pt9Si7 type, $$P{\bar{6}}$$ , a = 1116.7(2) pm, c = 435.86(7) pm, wR2 = 0.0379, 1358 F2 values, 45 variables for Eu5In9Pt7. The platinum and indium atoms form covalently bonded [In13Pt9] and [In9Pt7] polyanionic networks which exhibit larger tunnels for the strontium and europium cations. They bind to these networks through electrostatic interactions as is evident from shorter Sr–Pt (339–353 pm) and Eu–Pt (298–334 pm) contacts. Temperature-dependent magnetic susceptibility measurements of Eu5In9Pt7 show Curie–Weiss behavior with an experimental magnetic moment of 7.51(1) µB/Eu, indicating stable divalent europium. This is corroborated by 151Eu Mossbauer spectroscopy. Eu5In9Pt7 orders antiferromagnetically at 11.6(5) K and shows a metamagnetic transition in the 2.5 K isotherm at a critical field of 2 kOe.