The preparation of an unsupported tetra-nuclear cluster with a linear Pt-0-Tl-1-Tl-1-Pt-0 metal chain is described. The complex shows strong red emission in the solid state, having a quantum yield of 73%. Density functional theory (DFT) and time-dependent DFT calculations show that red emission originated from a platinum to thallium-thallium charge-transfer excited state.