Five-membered metallacycloalkynes formed from group 4 metals and [n]cumulene (n = 3,5) ligands
Five-membered metallacycloalkynes formed from group 4 metals and [n]cumulene (n = 3,5) ligands
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DOI：
10.1016/j.ccr.2009.12.016
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发表时间：
2010-06
影响因子：
20.6
通讯作者：
N. Suzuki;D. Hashizume
中科院分区：
文献类型：
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作者：
N. Suzuki;D. Hashizume
本文描述了形成五元金属环的4族茂金属的[3]-和[5]堆积烯配合物。这些配合物有一个“三键”，尽管它们是五元环结构，表明它们被认为是1-金属环-3-炔。分子结构表现出应变炔的特征。这些配合物与过渡金属反应形成炔配位双金属配合物。它们也受到质子和硼烷的亲电攻击，导致M-C键断裂。当[3]累积烯与金属上的炔偶联时，反应产生具有应变结构的七元金属环炔，其“三键”与金属中心之间存在相互作用。六戊烯，[5]累积烯，形成共轭1-金属环烯-3-炔。芳基取代的[5]累积烯配合物被碱金属还原为二阴离子，与质子反应得到1-金属环戊-3-烯，即环烯烃，与碘甲烷反应得到1-金属环戊-2,3-二烯，即环allene。含叔丁基的六戊烯在三甲基膦的存在下与锆新统反应生成η - 2 π配位配合物，而在没有膦的情况下生成1-金属环-3-炔。前者通过加入磷化氢转变为后者，反之，通过去除磷化氢，表现出“亲触性”转变。
In this account [3]- and [5]cumulene complexes of group 4 metallocenes that form five-membered metallacycles are described. These complexes have a “triple bond” despite their five-membered ring structure, showing that they are regarded as 1-metallacyclopent-3-ynes. The molecular structures show their strained alkyne character. These complexes react with transition metals to form alkyne-coordinated bimetallic complexes. They also receive electrophilic attack by protons and boranes resulting in M–C bond cleavage. When a [3]cumulene couples with an alkyne on the metal, the reaction produces seven-membered metallacycloalkynes that have a strained structure showing an interaction between the “triple bond” and the metal center. Hexapentaenes, [5]cumulenes, form conjugated 1-metallacyclopent-3-ynes. The aryl-substituted [5]cumulene complex was reduced by alkali metal to give dianionic species that reacted with protons to give 1-metallacyclopent-3-ene, a cycloalkene, and with iodomethane to give 1-metallacyclopenta-2,3-diene, a cycloallene. The hexapentaene with tert-butyl groups reacts with zirconocene to form an η2-π-coordinated complex in the presence of trimethylphosphine, although it gave a 1-metallacyclopent-3-yne in the absence of the phosphine. The former was transformed into the latter by addition of a phosphine, and vice versa by removing the phosphine, showing a “haptotropic” shift.