Novel coordination modes of partially hydrogenated diyne ligands on metal carbonyl clusters

The reaction of [Ru₄H₄(CO)₁₂] with the 1, 3-diynes RC2C2R (R = Me, SiMe3 or Ph) under reflux conditions, in heptane, yielded the tetraruthenium clusters [Ru₄(CO), 2{n4-n'lI-(RCH2C3R)}] 1 and [Ru4(CO)I2{H4-Tl2:i2[RC(H)C]2}] 2 (R = Me a, SiMe3 b or Ph c) in good yield. In 1 a 1, 1-dihydrogenation occurs to generate an allene-1, 3diyl ligand, which coordinates to the butterfly Ru4 face in a novel n/ : n₁₂: r_12: r mode, whereas in 2 a 1, 4-dihydrogenation occurs to yield a l, 3-diene-2, 3-diyl ligand bound to the Ru4 butterfly via four C atoms in a r)2:1:1:!!2 mode. In addition, the trinuclear cluster [Ru3(u-H)(CO)₉{r2:n2:nI-[RCH2C2CHPh)] 3c (R = Ph) is produced as a result of 1, 1, 4 trihydrogenation of the diyne and loss of one ruthenium vertex. The clusters have fully been characterised SDectrosconicallv. and the crvstal structures of la.lc 2a.2c and 3c determined.