Abstract Triorganyltin hydroxides react with catechols in organic solvents in the presence of air oxygen at first to paramagnetic complexes which are investigated by ESR spectroscopy. The reaction has been run using 6 catechols and 5 different organometallic compounds in numerous solvents, so that its general application is proved. The ESR spectra of the solutions show typical hydrogen hyperfine structure and large splittings, which have to be ...