Transformations of Alkynes at a Cyclotriphosphato Ruthenium Complex

Photolysis of the cyclotriphosphato complex (PPN)[Ru(P 3 O 9 )(η 6 -C 6 H 6 )] ( 2 ) with bpy (2,2′-bipyridyl) in alcohols generated a violet solution of (PPN)[Ru(P 3 O 9 )(bpy)(ROH)] ( 3 ) with a labile alcohol ligand. Complexes 3 were readily oxidized during recrystallization to give the Ru(III) alkoxo complexes (PPN)[Ru(OR)(P 3 O 9 )(bpy)] ( 4 ). Treatment of 3 with internal alkynes led to selective formation of η 2 -alkyne complexes (PPN)[Ru(P 3 O 9 )(bpy)(η 2 -RC≡CR′)] ( 7 ), which did not undergo vinylidene rearrangement under heating and photoirradiation conditions in contrast to its dppe analogues. On the other hand, diphenylacetylene complex 7c (R = R′ = Ph) gave the α-ketocarbene complex (PPN)[Ru(P 3 O 9 )(bpy)(═CPhCOPh)] ( 8 ) on reaction with m -CPBA. This observation provides a very rare example for the direct and controlled oxidation of a coordinated alkyne ligand. Reactions of 3 with the terminal alkynes in alcohols and in DMF afforded the alkoxycarbene complexes (PPN)[Ru(P 3 O 9 )(bpy){═C(OR)CH 2 CR′}] ( 9 ) and the carbonyl complex (PPN)[Ru(P 3 O 9 )(CO)(bpy)] ( 12 ), respectively, presumably by way of vinylidene intermediates.