Acridine reacts with an acetone solution of rhenium(III) chloride to afford the acridinium salt [AcrH] 2Re 3Cl 8, the first complex chloride of rhenium(II) chloride to have been isolated. Acridinium hydrochloride is isolated as a by-product of this redox reaction. As part of the characterization of this derivative, its X-ray photoelectron spectrum has been recorded and the rhenium 4 f and chlorine 2 p binding energies measured. Related studies have also been made on several salts of the Re 3Cl 11 2− and Re 3Cl 12 3− anions. The chlorine 2p 1 2 and 2p 3 2 binding energies of [AcrH] 2CoCl 4 and [CoCl 2. Acr] n − both new complexes - together with [ pyH] 2CoCl 4 and [CoCl 2.2py] n , are also reported and the use of this technique in distinguishing different types of metal-chlorine bonds is discussed.