The alkyne RCCR, R = CO2Me, reacts with 5-membered metallacycles [PtMe2{SnM
e2ESnMe2E}(bu(2)bpy)], E = S, Se or Te, bu(2)bipy = 4,4'-di-tert-butyl-2,2'
-bipyridine, yielding the corresponding 7-membered metallacycles [PtMe2-{Sn
Me2ESnMe2CR=CRE}(bu(2)bpy)] which slowly eliminate "Me2SnE" to give new 5-m
embered metallacycles [PtMe2-{SnMe2CR=CRE}(bu(2)bpy)]; further reaction of
which with excess RCCR gives [PtMe2(CR=CRH)(CCR)(bu(2)bpy)], a complex whic
h contains alkyl, alkenyl and alkynyl functionalities in the same molecule.