The preparation of an unsupported tetranuclear cluster with a linear Pt⁰–Tl^I–Tl^I–Pt⁰ 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.