Reactivity of a Triruthenium Acetylide Complex toward Alkynes and the Silica-Mediated Dehydration of Cluster-Bound Alkynols: X-ray Crystal Structures of the Novel Butadienyl Species [Ru₃(CO)₈{μ₃-η⁸-C(Bu^t)CC(Ph)C(H)Ph}] and the Unusual Complex [Ru₃(CO)₅(μ-CO){μ₃-η⁵-CC(Bu^t)- OC(Ph)₂CCH}{μ₃-η⁶-CHC(CPh₂OH)COC(CPh₂)CH}]

The lightly ligated complex [Ru3(CO)8(MeCN)(μ-H)(μ-C2But)] (4), derived from [Ru3(CO)9(μ-H)(μ-C2But)](1), reacts with terminal alkynes and alkynols under very mild conditions to give high yields of products derived from addition of three molecules of alkyne/alkynol. More interestingly, complex 4 also reacts with diphenylacetylene to form the novel butadienylic species [Ru3(CO)8{μ3-η8-C(But)CC(Ph)C(H)Ph}] (6), stabilized by an uncommon interaction between a phenyl substituent and a cluster metal atom. Its formation represents a key step in understanding the reaction mechanism leading to tri- and tetra-alkyne-substituted derivatives. The acetonitrile derivative of 6 reacts further with diphenylacetylene to afford the complex [Ru3(CO)7{μ3-η8-C(But)CC(Ph)C(H)Ph}{μ3-η4-C(Ph)C(Ph)}] (7), which, upon heating, isomerizes to give [Ru3(CO)7{μ3-η8-C(But)CC(Ph)C(Ph)H}{μ3-η4-C(Ph)C(Ph)}](2) in high yield. The analogous complex [Ru3(CO)7{μ3-η8-C(But)CC(Ph)C(CPh2OH)H}{μ3-η4-C(CPh2OH)C (Ph)}] (8) is formed directly from 4 through reaction with 1,1,3-triphenyl-2-propyn-1-ol. Finally, the tetra-alkyne-substituted metallacyclic complex [Ru3(CO)6{μ3-η6-C(But)CC(CPh2OH)CH2}{μ3-η6-CHC(CPh2OH)COC(CPh2OH)CH}] (5a), obtained from reaction of 1,1-diphenyl-2-propyn-1-ol with 4, undergoes facile dehydration in the presence of silica gel to yield the cluster complex [Ru3(CO)5(μ-CO){μ3-η5-CC(But)OC(Ph)2CCH}{μ3-η6-CHC(CPh2OH)COC(CPh2)CH}] (9), a process that involves formation of an unusual heterocycle. In addition, complex 9 contains a terminal carbene unit, one of the first examples of such a ligand in a cluster complex. The structures of complexes 6, 8, and 9 have been determined crystallographically and are discussed in association with possible reaction mechanisms.由[Ru₃(CO)₉(μ-H)(μ-C₂Buᵗ)]（1）衍生得到的配位数较低的络合物[Ru₃(CO)₈(乙腈(acetonitrile，缩写MeCN))(μ-H)(μ-叔丁基乙炔基(μ-C₂Buᵗ))]（4），在极温和条件下与端炔（terminal alkynes）及炔醇（alkynols）反应，可高收率获得由三分子炔/炔醇加成生成的产物。更为有趣的是，络合物4亦可与二苯乙炔（diphenylacetylene）反应，生成新型丁二烯基类物种（butadienylic species）[Ru₃(CO)₈{μ₃-η⁸-C(Buᵗ)=CC(Ph)=C(H)Ph}]（6），该簇通过罕见的苯基取代基（phenyl substituent）与簇金属原子（cluster metal atom）间的相互作用得以稳定。该络合物的生成过程是阐明三取代炔基衍生物（tri-alkyne-substituted derivatives）及四取代炔基衍生物（tetra-alkyne-substituted derivatives）反应机理的关键步骤。络合物6的乙腈衍生物（acetonitrile derivative）可进一步与二苯乙炔反应，得到络合物[Ru₃(CO)₇{μ₃-η⁸-C(Buᵗ)=CC(Ph)=C(H)Ph}{μ₃-η⁴-C(Ph)=C(Ph)}]（7）；该络合物在加热条件下可高收率异构为[Ru₃(CO)₇{μ₃-η⁸-C(Buᵗ)=CC(Ph)=C(Ph)H}{μ₃-η⁴-C(Ph)=C(Ph)}]（2）。类似的络合物[Ru₃(CO)₇{μ₃-η⁸-C(Buᵗ)=CC(Ph)=C(CPh₂OH)H}{μ₃-η⁴-C(CPh₂OH)=C(Ph)}]（8）可由络合物4与1,1,3-三苯基-2-丙炔-1-醇直接反应制得。最后，由1,1-二苯基-2-丙炔-1-醇与络合物4反应得到的四取代炔基金属环三核钌簇络合物（metallacyclic complex）[Ru₃(CO)₆{μ₃-η⁶-C(Buᵗ)CC(CPh₂OH)CH₂}{μ₃-η⁶-CHC(CPh₂OH)COC(CPh₂OH)CH}]（5a），可在硅胶（silica gel）存在下易发生脱水反应（dehydration），生成簇合物[Ru₃(CO)₅(μ-CO){μ₃-η⁵-CC(Buᵗ)OC(Ph)₂CCH}{μ₃-η⁶-CHC(CPh₂OH)COC(CPh₂)CH}]（9），该过程涉及一种罕见杂环的生成。此外，络合物9含有一个终端卡宾单元（terminal carbene unit），这是簇合物中此类配体的首批报道案例之一。络合物6、8及9的结构已通过晶体学方法（crystallographically）测定，并结合可能的反应机理进行了讨论。