In summary, the M₂C₃⁻ (M = Os, Ir, Pt) complexes have been successfully synthesized and characterized by using photoelectron spectroscopy. The experimental VDEs of Os₂C₃⁻, Ir₂C₃⁻ and Pt₂C₃⁻ are measured to be 2.75±0.09, 3.05±0.08, and 2.06±0.03 eV, respectively. These experimental values are in excellent agreement with the theoretical values obtained from quantum chemical calculations. While the structures of Os₂C₃⁻ and Ir₂C₃⁻ have linear chains with two terminal metal atoms, Pt₂C₃⁻ adopts a slightly twisted zigzag chain. All the M₂C₃⁻ (M = Os, Ir, Pt) complexes are stabilized by the delocalized π bonding interactions among all the five atoms, indicative of a [M=C=C=C=M]⁻ carbene with potentially high reactivity toward a large variety of small molecules (CO₂, N₂, H₂O, CH₄, etc). The present findings advance the characterization of novel metal carbenes and afford important insights into the development of related single-atom/cluster catalysts.