Ternary silicides ScIr4Si2 and RERh4Si2 (RE = Sc, Y, Tb-Lu) and quaternary derivatives RERh4Si2–xSnx (RE = Y, Nd, Sm, Gd-Lu) – structure, chemical bonding, and solid state NMR spectroscopy

Abstract

Abstract The silicides ScIr4Si2 and RERh4Si2 (RE=Sc, Y, Tb-Lu) and silicide stannides RERh4Si2–x Sn x (RE=Y, Nd, Sm, Gd-Lu) were synthesized from the elements by arc-melting and subsequent annealing. The new compounds crystallize with the orthorhombic YRh4Ge2 type structure, space group Pnma. They were characterized by X-ray powder patterns and several structures were refined from single crystal X-ray diffractometer data. The main structural motifs of this series of silicides are tricapped trigonal prisms formed by the transition metal and rare earth atoms. One of the two crystallographically independent silicon sites allows for formation of solid solutions with tin, exemplarily studied for ErRh4Si2–x Sn x . Electronic structure calculations reveal strong covalent Rh–Si bonding as the main stability factor. Multinuclear (29Si, 45Sc, and 89Y) magic-angle spinning (MAS) NMR spectra of the structure representatives with diamagnetic rare-earth elements (Sc, Y, Lu) are found to be consistent with the crystallographic data and specifically confirm the selective substitution of Sn in the Si2 sites in the quaternary compounds YRh4SiSn and LuRh4SiSn.