High-Pressure Synthesis of a Silicon-Rich Ruthenium Silicide, RuSi ₃ , with a 9-Coordinated Ru Site and a Si–Si Dumbbell

has a semimetallic and pseudogap electronic structure and contains a short Si-Si covalent bond network connecting the Ru-Si polyhedra. Our findings not only suggest the possibility of discovering novel silicon-rich transition metal silicides but also unequivocally demonstrate that high-pressure synthesis is an effective strategy for significantly expanding the structural diversity of this compound class.