Abstract: | Highly metallic compounds with a quasi‐one‐dimensional structure, the new ternary compounds Ln2Al3Si2 (Ln=Ho, Er, Tm) are synthesized in molten aluminum from lanthanoid and silicon as reagents. Their structures show a formally Al3Si2]6− framework that contains infinite Al zigzag chains and Si−Si dimers and accommodates rows of Ln3+ ions in parallel tunnels. The compounds exhibit metamagnetic transitions at high magnetic fields. |