Alkyne Dichotomy: Splitting of Bis(dialkylamino)acetylenes, Dimethoxyacetylene, Bis(methylthio)acetylene, and Their Heavier Congeners To Give Carbyne Ligands in Iron Carbonyl Derivatives

作者：Li Huidong; Feng Hao^*; Sun Weiguo; Xie Yaoming; King R Bruce; Schaefer Henry F III

来源：Organometallics, 2013, 32(1): 88-94.

DOI：10.1021/om3008426

The R2C2Fe2(CO)(6) complexes obtained from reactions of the alkynes RCCR with iron carbonyls are known experimentally to exhibit the following two types of structures: (1) tetrahedrane structures in which the alkyne carbons are incorporated into a central Fe2C2 tetrahedron with a short Fe=Fe distance, suggesting a formal double bond and (2) dichotomy structures in which the alkyne has split into two separate RC carbyne units bridging a singly bonded pair of iron atoms. The relative energies of these two structure types with different substituents R have now been examined using density functional theory. For the dialkylamino derivatives (R-2%26apos;N)(2)C2Fe2(CO)(6) (R%26apos; = CH3, C2H5) the dichotomy structures are preferred energetically over the tetrahedrane structures by 5-11 kcal/mol. For (CH3O)(2)C2Fe2(CO)(6) the dichotomy and tetrahedrane structures have comparable energies. Dichotomy structures as well as tetrahedrane structures were found for (CH3E)(2)C2Fe2(CO)(6) (E = S, Se) but not for (CH3Te)(2)C2Fe2(CO)(6) or (CH3SO)(2)C2Fe2(CO)(6). Only tetrahedrane structures were found for the alkyl derivatives R2C2Fe2(CO)(6) (R = (CH3)(3)C, CH3, C6H5) and R-2%26apos;C2Fe2(CO)(6) (R%26apos; = H, C5H4N).

• 出版日期2013-1-14
• 单位西华大学