Rhodium-rich germanides RERh4Ge2 (RE = Y, Gd–Lu): structure and bonding

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

“…The silicides RERh 4 Si 2 (RE = Sc, Y, Tb-Lu) are isotypic with the recently reported series of germanides RERh 4 Ge 2 [8], space group Pnma. The cell volumes of the silicides are about 5 % smaller than those of the germanides; a direct consequence of the smaller silicon atoms.…”

“…All data sets showed primitive orthorhombic lattices and the systematic extinctions were compatible with space group Pnma. Isotypy with the germanides RERh 4 Ge 2 [8] was already evident from the Guinier powder patterns. The atomic parameters of YRh 4 Ge 2 [8] were taken as starting values and the structures were refined on F 2 with Jana2006 [24] with anisotropic displacement parameters for all atoms.…”

“…Isotypy with the germanides RERh 4 Ge 2 [8] was already evident from the Guinier powder patterns. The atomic parameters of YRh 4 Ge 2 [8] were taken as starting values and the structures were refined on F 2 with Jana2006 [24] with anisotropic displacement parameters for all atoms. In case of the tin-containing compounds the mixed Sn/Si occupancy was refined as a least-squares variable.…”

“…Initially a well-shaped single crystal of SmRh 4 SiSn was found during our phase analytical studies of the series of RE 3 Rh 9 Si 2 Sn 3 [7] using bismuth as a non-reactive flux. Based on this discovery, targeted syntheses of the series were performed by melting the elements in an electric arc furnace [9] in an argon atmosphere of about 700 mbar, similar to the series of RERh 4 Ge 2 [8]. Argon was purified with titanium sponge (900 K), molecular sieves and silica gel.…”

“…Herein we report on a new series of silicides ScIr 4 Si 2 , RERh 4 Si 2 (RE = Sc, Y, Tb-Lu; YRh 4 Ge 2 type [8], Pnma) which contain two crystallographically independent silicon sites. The one with the slightly larger coordination sphere allows for silicon/tin substitution, leading to quaternary compounds RERh 4 SiSn (RE = Y, Nd, Sm, Gd-Lu).…”