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Iridium-catalyzed C–H borylation of aromatic and aliphatic hydrocarbons assisted by a directing group was theoretically investigated. Density functional theory (DFT) calculations revealed both Ir-catalyzed C(sp2)–H and C(sp3)–H borylations via an IrIII/IrVcatalytic cycle, where the tetra-coordinated (C, N)IrIII(Bpin)2complex with two vacant sites is an active species. Dramatically, the orientation of cyclometalation for C(sp2)–H bond activation assisted by a directing group is different from the C(sp3)–H one. The activation energy (ΔG°‡= 28.5 kcal mol–1) of the C(sp2)–H bond via trans-chelation to form cyclometalation is lower than that (41.4 kcal mol–1) via cis-chelation. In contrast, the ΔG°‡(26.6 kcal mol–1) of the C(sp3)–H bond via cis-chelation to form cyclometalation is lower than that (34.3 kcal mol–1) via trans-chelation. In addition, the rate-determining step of Ir-catalyzed C(sp2)–H borylation is oxidative addition of the C(sp2)–H bond, while that of C(sp3)–H analogues is hydride migration. Such differences arise from not only the differences in the steric hindrance of the C(sp2) and secondary C(sp3) atoms but also the differences in the trans effect and steric effect of the two vacant sites of active species. These findings were expected to facilitate further studies on the design and synthesis of innovative ligands for Ir-catalyzed C–H borylation.

For novel all-metal electride, multicage chain structures [(Ni@Ge9) Ca3]n(n= 1–4) with all real frequencies are obtained theoretically for the first time. In the structure of n= 1, the Ni@Ge9metal cage as the shortest chain skeleton is surrounded by nonbridge Ca atoms. In the structures of n= 2–4, Ni@Ge9metal cages are connected by bridge Ca atom pair(s) forming new hybrid multicage chain skeletons surrounded by nonbridge Ca atoms. And interesting pull–push electron relay occurs. The chain skeleton pulls valence electrons from nonbridge Ca atoms forming skeleton polyanion, and then formed polyanion pushes remaining valence electrons of the Ca atoms forming excess electrons. The excess electron numbers are Ne = 2, 0, 4, 4 for n= 1, 2, 3, 4, respectively. It is shown that these structures with excess electrons are molecular all-metal electride multicage chains, unexpectedly, and the structure (n= 2) without excess electron is a Ca salt. For nonlinear optical (NLO) response, the electride chains have large static first hyperpolarizabilities (β0e). And β0eincreases strongly from 9321 (n= 1, Ne= 2) to 54232 au (n= Ne= 4), which exhibits that significant cage number and excess electron number effects on NLO response. Besides electronic contribution (β0e) to static first hyperpolarizability, the large vibrational contribution (β0nr) are also revealed, and the ratios of β0nr/β0eare 0.18–1.17. Moreover, the frequency-dependent values βe(−2ω; ω, ω) and βe(−ω; ω, 0) have also been estimated. Especially, the evolutions of prominent cage number effects on β0e, β0nr, βe(−2ω; ω, ω) and βe(−ω; ω, 0) are similar. Then a new design strategy of enhancing NLO response by increasing metal-cage number is obtained. Hence, these molecular all-metal electride multicage chains as novel nanorods are promising new NLO nanomaterials.

Based on s-indaceno[1,2,3-cd;5,6,7-c′d′]diphenalene (1) consisting of two phenalenyl moieties, the monomer 2and its dimer 22are designed by boron and nitrogen atoms substituting the central carbon atoms of phenalenyl moieties. Calculated energy decompose analysis (EDA) shows that the orbital interaction for 22possesses a large attractive contribution of −18.31 kcal mol–1, which is dominated by the π–π stacking interaction between the upper and the lower π-conjugated units. Interestingly, the natural population analysis (NPA) charge and the transition density matrix (TDM) show that both intramolecular charge transfer and intermolecular charge transfer (CT) exist in 22. Further, the first hyperpolarizability (βtot= 4.56 × 104au) of 2with intramolecular CT is greatly larger than that of reported molecule 3(5.45 × 103au) with intermolecular CT. Significantly, 22exhibits the largest βtotvalue to be 1.42 × 105au, which is caused by combining the intra- and intermolecular CT transitions (βx= 1.40 × 105au and βz= 2.27 × 104au). Correspondingly, highest occupied molecular orbital (HOMO) → lowest unoccupied molecular orbital (LUMO) (intramolecular CT) in the low-energy electronic transition of 22is 68%, while HOMO → LUMO + 1 (intermolecular CT) is 18%, which demonstrates that the intramolecular CT effect on the βtotvalue is stronger than the case of the intermolecular CT effect. The present work might provide rich insight into designing and developing potential second-order optical nonlinearity materials with inter- and intramolecular CT characters.