Ruthenium Allenylidene and Allylcarbene Complexes from 1,6-Diyne

Reactions of the four 1,6-diynes 1−3 and 7, each with one terminal propargylic alcohol and one internal triple bond containing Me3Si groups, with [Ru]−Cl ([Ru] = Cp(PPh3)2Ru) led to two types of products. In the first type, only the propargylic group is involved in the reaction leading to vinylidene, allenylidene, or acetylide complexes. A C−C bond formation of two triple bonds in 1,6-diynes gave allylcarbene products of the second type. The reaction of 1 with [Ru]−Cl yielded only the first type, giving a mixture of two cationic complexes; the allenylidene complex 8 and the phosphonium acetylide complex 9, the latter resulting from further addition of a phosphine molecule to Cγ of 8. The same reaction in the presence of excess phosphine gave 9 only. However, with an additional methyl group, the 1,6-diyne 2 reacted with [Ru]−Cl to give the allylcarbene complex 11 also with a phosphonium group on the ligand. The reaction proceeds by a cyclization reaction involving two triple bonds on the metal accompanied by a migration of a phosphine ligand to Cα. In both reactions strong affinity between alkyne and phosphine was observed, resulting in formations of P−C bonds with different regioselectivity. Addition of HCl to 11 transforms the five-electron-donor allylcarbene ligand to the four-electron-donor diene ligand along with formation of a Ru−Cl bond, giving complex 12 in high yield. From the reaction of [Ru]−Cl with diyne 3 containing a tert-butyl group at the propargylic carbon, both the allenylidene complex 13 and the allylcarbene complex 14 were obtained. The reaction of diyne 7 with [Ru]−Cl also gave both types of complexes, namely the vinylidene complex 16 and the allylcarbene complex 17. Crystal structures of complexes 9, 11, 12, and 16 have been determined by single-crystal X-ray diffraction analysis.

四种分别带有一个末端炔丙醇基与一个含三甲基硅基（Me3Si）内三键的1,6-二炔1~3及7，与[Ru]-Cl（其中[Ru] = Cp(PPh3)2Ru，即环戊二烯基二(三苯基膦)合钌）发生反应，可生成两类产物。第一类产物仅由炔丙基参与反应得到，对应亚乙烯基、丙二烯亚基或炔化物金属络合物；第二类产物则通过1,6-二炔中两个三键的碳碳键偶联，生成烯丙基卡宾类产物。

1与[Ru]-Cl的反应仅得到第一类产物，为两种阳离子络合物的混合物：丙二烯亚基络合物8与鏻盐炔化物络合物9，后者由膦分子进一步加成至8的Cγ位生成。若在反应体系中加入过量膦配体，则仅能得到产物9。

带有额外甲基的1,6-二炔2与[Ru]-Cl反应，可生成配体上带有鏻盐基团的烯丙基卡宾络合物11。该反应经由金属表面两个三键的环化过程，并伴随膦配体向Cα位的迁移而进行。两类反应中均观察到炔烃与膦配体间的强亲和作用，以不同的区域选择性形成P-C键。

向11中加入氯化氢，可将五电子给体的烯丙基卡宾配体转化为四电子给体的二烯配体，同时形成Ru-Cl键，以高收率得到络合物12。

由炔丙基碳上带有叔丁基的二炔3与[Ru]-Cl的反应，可同时得到丙二烯亚基络合物13与烯丙基卡宾络合物14。二炔7与[Ru]-Cl的反应同样生成两类络合物，即亚乙烯基络合物16与烯丙基卡宾络合物17。

络合物9、11、12及16的晶体结构已通过单晶X射线衍射分析得以确定。