The Gallides SrRh₂Ga₂, SrIr₂Ga₂, and Sr₃Ir₄Ga₄

Abstract

Abstract The gallides SrRh 2 Ga 2 , SrIr 2 Ga 2 , and Sr 3 Rh 4 Ga 4 were obtained from the elements by induction melting and subsequent annealing. They were investigated by powder and single‐crystal X‐ray diffraction: CaRh 2 B 2 type, Fddd , a = 573.2(1), b = 1051.3(1), c = 1343.7(2) pm, wR 2 = 0.0218, 398 F 2 values, 15 variables for SrRh 2 Ga 2 ; a = 576.0(1), b = 1045.5(1), c = 1350.6(3) pm for SrIr 2 Ga 2 , and Na 3 Pt 4 Ge 4 type, I $\bar{4}$ 3 m, a = 777.4(2) pm, wR 2 = 0.0234, 190 F 2 values, 11 variables for Sr 3 Ir 4 Ga 4 . The gallides SrRh 2 Ga 2 and Sr 3 Ir 4 Ga 4 exhibit complex, covalently bonded three‐dimensional [Rh 2 Ga 2 ] and [Ir 4 Ga 4 ] networks with short Rh–Ga (241–246 pm) and Ir–Ga (243–259 pm) distances. The strontium atoms fill large cages within these networks. They are coordinated by 8 Rh + 10 Ga in SrRh 2 Ga 2 and by 4 Ir + 8 Ga in Sr 3 Ir 4 Ga 4 . The structure of SrRh 2 Ga 2 is discussed along with the monoclinic distortion variants HoNi 2 B 2 and BaPt 2 Ga 2 on the basis of a group‐subgroup scheme.