Many Density Functional Theory Approaches Fail To Give Reliable Large Hydrocarbon Isomer Energy Differences

[structure: see text] Several DFT methods were found to be unreliable for computing hydrocarbon isomer energy differences. The errors grow with system size up to 20 kcal mol(-1) for the relative energies of the (CH)12 isomers; octahedrane is the most stable (CH)12 hydrocarbon. While DFT geometries generally are good, problems arise for structures with single bonds only, especially for small rings. We recommend the use of higher level, non-DFT energy single points computed at DFT-optimized structures.

Theoretical Designs for Planar Tetracoordinated Carbon in Cu, Ag, and Au Organometallic Chemistry: A New Target for Synthesis

In the past 30 years, substantial efforts and progress have been made in the design and synthesis of molecules containing tetracoordinated planar carbon, by overcoming the inherent preference for tetrahedral bonding. As a result, we have studied 12 organometallic molecules containing group 11 elements (i.e., M-X; M = Cu, Ag, and Au and X = I, II, III, and IV) using density functional theory to determine whether the central carbon atom exists in a planar geometry. Our theoretical findings suggest that in such M-X species, bonding interactions between the central carbon and the coinage metal ligands and between the metal ligands (i.e., metallophilic attractions) are both important in favoring planar-tetracoordinated carbon compounds over the corresponding tetrahedral structures. The compounds studied in this work are seen as excellent targets for chemical synthesis.