Dihydridocarbonyltris (triphenylphosphine)ruthenium (Ru)-catalysed copolymerization of 4-benzoylpyridine and 1,3-divinyltetramethyldisiloxane leads to a mixture of 2,3-benzo-6,6,8,8-tetramethyl-7-oxa-11,12-m-pyridino-6,8-disilacyclododecan-1-one, cyclic co-monomer (I), and copoly (2＇,3-[4-benzoylpyridinylene]/3,3,5,5-tetramethyl-4-oxa-3,5-disilaheptanylene). Similarly, Ru-catalysed reaction of benzophenone and I,3-divinyltetramethyldisiloxane leads to a mixture of 5,6,8,9-dibenzo-2,2,12,12-tetramethyl-1-oxa-2,12-disilacyclododeca-7-one, cyclic co-monomer (III) and copoly (2,2＇-benzophenonylene alt. 2,6-benzophenonylene/3,3,5,5-tetramethyl-4-oxa-3,5-disila-1,7-heptanylene). The formation of these products apparently results from the fact that only two of the four ortho hydrogens of 4-benzoylpyridine or benzophenone are reactive under Ru catalysis. Further, preferential reaction of one ortho hydrogen on each aromatic ring of 4-benzoylpyridine or benzophenone takes place. Products have been characterized by H-1, C-13, Si-29 n.m.r., i.r., u.v.-vis spectroscopy, as well as elemental analysis and/or high resolution peak matching. In addition, g.p.c., d.s.c., and t.g.a. of copolymers have been determined.