The effect of substitution on the potential energy surfaces of RE13≡BiR (E13 = B, Al, Ga, In, and Tl; R = F, OH, H, CH3, SiH3, Tbt, Ar*, SiMe(SitBu3)2, and SiiPrDis2) is investigated using density functional theories (M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp). The theoretical results suggest that all of the triply bonded RE13≡BiR molecules prefer to adopt a bent geometry (i.e., ∠RE13Bi ≈ 180° and ∠E13BiR ≈ 90°), which agrees well with the bonding model (model (B)). It is also demonstrated that the smaller groups, such as R = F, OH, H, CH3, and SiH3, neither kinetically nor thermodynamically stabilize the triply bonded RE13≡BiR compounds, except for the case of H3SiB≡BiSiH3. Nevertheless, the triply bonded RʹE13≡BiRʹ molecules that feature bulkier substituents (Rʹ = Tbt, Ar*, SiMe(SitBu3)2, and SiiPrDis2) are found to have the global minimum on the singlet potential energy surface and are both kinetically and thermodynamically stable. In other words, both the electronic and the steric effects of bulkier substituent groups play an important role in making triply bonded RE13≡BiR (Group 13–Group 15) species synthetically accessible and isolable in a stable form.
Part of the book: Recent Progress in Organometallic Chemistry
The potential energy surfaces of the oxidative addition reactions, L2M + imidazoliumcation → product and CpM′L + imidazolium cation → product (M = Ni, Pd, Pt; M′ = Co, Rh, Ir; Cp = η5-C5H5; L = 1,3-aryl-N-heterocyclic carbene (NHC), aryl = 2,4,6-trimethylphenyl), are studied at the M06-L/Def2-SVP level of theory. The theoretical findings show that the singlet-triplet splitting (∆Est = Etriplet − Esinglet) for the L2M and CpM′L species can be used to predict the reactivity for their oxidative additions. That is to say, current theoretical evidence suggests that both a 14-electron L2M complex and a 16-electron CpM′Lcomplex with a better electron-donating ligand L (such as NHC) result in a reduced ∆Est value and facilitate the oxidative addition to the saturated C─H bond. The theoretical results for this study are in good agreement with the obtainable experimental results and allow a number of predictions to be made.
Part of the book: Descriptive Inorganic Chemistry Researches of Metal Compounds