Solvent-free room-temperature synthesis of brightly luminescent [BMPyr]$_2$[SnCl$_4$]

The pseudo-ternary tin(II) halide [BMPyr]$_2$[SnCl$_4$] can be obtained just by mixing the starting materials [BMPyr]Cl and SnCl$_2$ at room temperature without additional solvents. The compound shows bright Sn(II)-based emission of deep-red light (λ$_{max}$: 740 nm) with a quantum yield of 88 ± 3% after optimised synthesis. Characterization is performed by X-ray structure analysis, infrared and fluorescence spectroscopy. Exemplary fluorescent thinfilms are realized by solvent processing.