Mono-o-semiquinonato mixed-halogenato tin(IV) complexes: EPR spectroscopic and X-ray investigations

► A series of new mono-semiquinonato trihalogenato tin(IV) complexes were synthesized. ► EPR reveals geometric isomers of complexes with different halide ligand in apical position. ► Molecular structures of complexes SQSnHal3 were confirmed by X-ray analysis. ► Such complexes form salts of SQSnHal4- type with ammonia halides.