EPR investigations of a thermally produced Mo(V) species in (NH₄)₂SnCl₆ and K₂SnCl₆, crystals doped with MoO₄^2-

We have employed the method of electron paramagnetic resonance (EPR) to investigate a Mo(VI) to Mo(V) reduction in (NH₄)₂SnCl₆:MoO₄^2- crystals thermally treated at temperatures below the decomposition temperature of the host compound. A similar Mo(V) species can be thermally produced in K₂SnCl₆: MoO₄^2- crystals codoped with either the NH₄⁺ or the CH₃NH₃⁺ ion, or by placing the crystals inside a polycrystalline mass of one of the following five compounds; namely, NH₄Cl, NH₄Br, NH₄ClO₄, (NH₄)SO₄, and CN₃NH₂·HCl. The EPR spectrum of this thermally produced Mo(V) species exhibited tetragonal symmetry, a molybdenum hyperfine structure, and a chlorine superhyperfine structure. We tentatively assign the structure of this Mo(V) species to a [MoOCl₅]^2- complex ion.