Center for Computational Quantum Chemistry, South China Normal University, Guangzhou 510631, P.R. China.
Dalton Trans. 2012 May 28;41(20):6225-31. doi: 10.1039/c2dt30405h. Epub 2012 Apr 11.
The mononuclear Mn(CO)(5)X and binuclear Mn(2)(CO)(8)(μ-X)(2) manganese carbonyl halides have long been known for the halogens Cl, Br, and I. However, the corresponding manganese carbonyl fluorides (X = F) remain unknown. The structures and thermochemistry of such manganese carbonyl fluorides and their decarbonylation products have now been investigated using density functional theory. In all cases singlet structures were found to have lower energies than the corresponding triplet structures. The expected octahedral structure is predicted for Mn(CO)(5)F. Decarbonylation of Mn(CO)(5)F is predicted to give trigonal bipyramidal Mn(CO)(4)F with equatorial fluorine. Further, decarbonylation gives tetrahedral Mn(CO)(3)F. All of the binuclear Mn(2)(CO)(n)F(2) structures (n = 8, 7, 6) are predicted to have a central Mn(2)F(2) unit with two bridging F atoms, a non-bonding Mn···Mn distance of ~3.1 Å, and exclusively terminal CO groups. The thermochemistry of these manganese carbonyl fluorides indicates that they are viable species. This suggests that the failure to date to synthesize the simple manganese carbonyl fluorides arises from a lack of a suitable synthetic method rather than from the instability of the desired products.
单核 Mn(CO)(5)X 和双核 Mn(2)(CO)(8)(μ-X)(2) 锰羰基卤化物早已为人所知，其中 X 为卤素 Cl、Br 和 I。然而，相应的锰羰基氟化物（X = F）仍然未知。现在使用密度泛函理论研究了这些锰羰基氟化物及其脱羰产物的结构和热化学。在所有情况下，单重态结构的能量都低于相应的三重态结构。预计 Mn(CO)(5)F 将具有八面体结构。预计 Mn(CO)(5)F 的脱羰反应将生成具有赤道氟的三角双锥 Mn(CO)(4)F。此外，脱羰反应生成四面体形 Mn(CO)(3)F。所有双核 Mn(2)(CO)(n)F(2) 结构（n = 8、7、6）都预计具有中央 Mn(2)F(2) 单元，带有两个桥接 F 原子，非键 Mn···Mn 距离约为 3.1 Å，并且仅具有端 CO 基团。这些锰羰基氟化物的热化学表明它们是可行的物质。这表明到目前为止未能合成简单的锰羰基氟化物是由于缺乏合适的合成方法，而不是由于所需产物的不稳定性。
