in chloroform reagents were mixed; product was filtered off, washed with chloroform and dried in air; elem.anal.;

in toluene N2 atmosphere; addn. of soln. of benzoquinone to suspn. of SnI2 (dropwise), refluxig (4 h), addn. of bipyridine, pptn., refluxing (1 h), cooling (room temp.); filtration off, washing (light petroleum), drying (vac.); elem. anal., IR spectroscopy;