Propargyl-dicobalt carbonyl complexes (R¹C₂CR²R³)Co₂(CO)₆⁺Z⁻ (2), first discovered nearly fifty years ago, have been extensively investigated and developed as useful reagents for propargyl-nucleophile coupling reactions. However, aside from early spectroscopic and semi-empirical theoretical studies, the structures, electronic properties and reactivity of these compounds have received scant attention using more rigorous computational methods. In this report a DFT analysis is presented of the structures, electronic character, stability, fluxionality and reactivity of two sets of propargyl complexes, the –Co₂(CO)₆ derivatives 2 and (R¹C₂CR²R³)Co₂(CO)₅(PZ₃)⁺Z⁻ (3), focusing on the effects of substituents and auxiliary ligands. The key findings include: 1) confirmation of their η²,η³-low temperature-limiting unsymmetrical structures; 2) that most substituents on the propargyl unit have relatively small effects on their stability, while auxiliary ligands of 3 can have substantial stabilizing effects; 3) calculated atomic charges, frontier MO analysis, IR and NMR spectra together indicate extensive electronic delocalization in 2 and 3, with a majority of positive charge dispersed onto the -Co₂(CO)_5,6(L) unit and a greater residual charge and LUMO character on C1 of the propargyl unit; 4) the latter factors account for the regioselective C-1 attack of nucleophiles on 2 and 3; 5) that two isomerization processes, enantiomerization and syn/anti diastereomerization, are viable via corresponding parallel and perpendicular transition states, the former generally being the lower in energy by ca. 2-3 kcal/mol); 6) that C-3 substituents on the propargyl unit, with one exception (R¹=OR), have small effects on these isomerization barriers, as is case for electron-poor phosphines, e.g. L=PF₃; 7) that stronger donor phosphines increase rigidity, stability and isomerization barriers, but non-linearly; and 8) that an alternative dynamic isomerization process, involving tetrahedral-to-planar squashing of the Co₂C₂ cluster, could be energetically accessible. Insights into the underlying factors causing these effects are presented along with some prospects for new reactivity and selectivity possibilities.

炔丙基羰基二钴羰基复合物（R ¹ c ^ ₂ CR ² - [R ³）有限公司₂（CO）₆ ⁺ ž ^- （2），第一近五十年前就发现，已被广泛地用于炔丙基亲核试剂偶联反应研究和作为有用试剂开发。然而，除了早期的光谱学和半经验理论研究以外，使用更严格的计算方法还很少关注这些化合物的结构，电子性质和反应性。在本报告中，DFT分析了两组炔丙基配合物–Co ₂的结构，电子特性，稳定性，通量和反应性。（CO）_6个衍生物2和（R ¹ c ^ ₂ CR ² - [R ³）有限公司₂（CO）₅（PZ ₃）⁺ ž ^- （3），着眼于取代基和配体辅助的效果。的主要结果包括：1）它们的η的确认²，η ³ -低温度限制不对称结构; 2）炔丙基单元上的大多数取代基对其稳定性的影响相对较小，而3的辅助配体具有很大的稳定作用；3）计算得出的原子电荷，前沿MO分析，IR和NMR光谱共同表明在2和3中存在广泛的电子离域，大部分正电荷分散在-Co ₂（CO）_5,6（L）单元上，并且残留量更大炔丙基单元C1的电荷和LUMO特征；4）后面的因素解释了亲核试剂对2和3的区域选择性C-1攻击；5）两种异构化过程，对映异构化和顺/反非对映异构化，可通过相应的平行和垂直进行过渡态，前者的能量通常较低约。2-3 kcal / mol）；6）炔丙基单元上的C-3取代基，除了一个例外（R ¹ = OR），对这些异构化壁垒的影响很小，对于电子贫化的膦来说，例如L = PF ₃；7）较强的供体膦增加了刚性，稳定性和异构化障碍，但呈非线性关系；和8）可以通过能量途径获得另一种动态异构化方法，该方法涉及Co ₂ C ₂团簇的四面体至平面挤压。介绍了引起这些影响的潜在因素，并提出了一些新的反应性和选择性可能性的前景。