Jia-Syun Lu

A possible target: triple-bonded indiumantimony molecules with high stability

We have considered as a theoretical possibility the development of triple-bonded RInSbR molecules bearing suitable substituents (R). Calculations have demonstrated that the RInSbR molecules possessing smaller substituents (such as R = F, OH, CH3, H, and SiH3) cannot be stabilized. Only the triple-bonded R′InSbR′ molecules featuring sterically bulky groups (R′ = SiMe(SitBu3)2, SiiPrDis2, Tbt (= C6H2-2,4,6-{CH(SiMe3)2}3), and Ar* (= C6H3-2,6-(C6H2-2,4,6-i-Pr3)2)) are found to locate on the global minimum of the singlet potential energy surface and are thermodynamically stable. The valence-electron bonding model reveals that the bonding nature of R′InSbR′ can be represented as . Our computational investigations based on several theoretical methods (i.e., the charge decomposition analysis, the natural bond orbital analysis and the natural resonance theory) reveal that both the electronic and steric effects of bulkier substituent groups play important roles in making triple-bonded R′InSbR′ species synthetically accessible and isolable in a stable form.

Triply-bonded indium[triple bond, length as m-dash]phosphorus molecules: theoretical designs and characterization

The effect of substitution on the potential energy surfaces of triple-bonded RInPR (R = F, OH, H, CH3, SiH3, NHC, SiMe(SitBu3)2 and SiiPrDis2) species was investigated, using the density functional theory (i.e., M06-2X/Def2-TZVP, B3PW91/Def2-TZVP and B97-D3/LANL2DZ+dp). The theoretical results suggest all of the triple-bonded RInPR molecules prefer to adopt a bent form with an angle (∠In–P–R) of about 90°. Present theoretical evidence suggests only the bulkier substituents, in particular for the strong donating groups (such as the NHC group), can greatly stabilize the InP triple bond. In addition, bonding analyses demonstrate the bonding character of such triple-bonded RInPR compounds should be represented as . That is to say, the InP triple bond contains one traditional σ bond, one traditional π bond, and one donor–acceptor π bond. As a consequence, the theoretical findings strongly suggest the InP triple bond in acetylene analogues (RInPR) should be very weak.

Triple Bonds between Bismuth and Group 13 Elements: Theoretical Designs and Characterization

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.

Substituent Effects on the Stability of Thallium and Phosphorus Triple Bonds: A Density Functional Study

Three computational methods (M06-2X/Def2-TZVP, B3PW91/Def2-TZVP and B3LYP/LANL2DZ+dp) were used to study the effect of substitution on the potential energy surfaces of RTl≡PR (R = F, OH, H, CH3, SiH3, SiMe(SitBu3)2, SiiPrDis2, Tbt (=C6H2-2,4,6-(CH(SiMe3)2)3), and Ar* (=C6H3-2,6-(C6H2-2, 4,6-i-Pr3)2)). The theoretical results show that these triply bonded RTl≡PR compounds have a preference for a bent geometry (i.e., ∠R⎼Tl⎼P ≈ 180° and ∠Tl⎼P⎼R ≈ 120°). Two valence bond models are used to interpret the bonding character of the Tl≡P triple bond. One is model [I], which is best described as TlP. This interprets the bonding conditions for RTl≡PR molecules that feature small ligands. The other is model [II], which is best represented as TlP. This explains the bonding character of RTl≡PR molecules that feature large substituents. Irrespective of the types of substituents used for the RTl≡PR species, the theoretical investigations (based on the natural bond orbital, the natural resonance theory, and the charge decomposition analysis) demonstrate that their Tl≡P triple bonds are very weak. However, the theoretical results predict that only bulkier substituents greatly stabilize the triply bonded RTl≡PR species, from the kinetic viewpoint.

Triply Bonded Gallium≡Phosphorus Molecules: Theoretical Designs and Characterization

The effect of substitution on the potential energy surfaces of triple-bonded RGa≡PR (R = F, OH, H, CH3, SiH3, SiMe(SitBu3)2, SiiPrDis2, Tbt (C6H2-2,4,6-{CH(SiMe3)2}3), and Ar* (C6H3-2,6-(C6H2-2,4,6-i-Pr3)2)) compounds was theoretically examined by using density functional theory (i.e., M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp). The theoretical evidence strongly suggests that all of the triple-bonded RGa≡PR species prefer to select a bent form with an angle (∠Ga-P-R) of about 90°. Moreover, the theoretical observations indicate that only the bulkier substituents, in particular, for the strong donating groups (e.g., SiMe(SitBu3)2 and SiiPrDis2) can efficiently stabilize the Ga≡P triple bond. In addition, the bonding analyses (based on the natural bond orbital, the natural resonance theory, and the charge decomposition analysis) reveal that the bonding characters of such triple-bonded RGa≡PR molecules should be regarded as [Formula: see text]. In other words, the Ga≡P triple bond involves one traditional σ bond, one traditional π bond, and one donor-acceptor π bond. Accordingly, the theoretical conclusions strongly suggest that the Ga≡P triple bond in such acetylene analogues (RGa≡PR) should be very weak.

Indium–Arsenic Molecules with an In≡As Triple Bond: A Theoretical Approach

The effect of substitution on the potential energy surfaces of RIn≡AsR (R = F, OH, H, CH3, and SiH3 and R′ = SiMe(SitBu3)2, SiiPrDis2, and N-heterocyclic carbene (NHC)) is determined using density functional theory calculations (M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp). The computational studies demonstrate that all of the triply bonded RIn≡AsR species prefer to adopt a bent geometry, which is consistent with the valence electron model. The theoretical studies show that RIn≡AsR molecules that have smaller substituents are kinetically unstable with respect to their intramolecular rearrangements. However, triply bonded R′In≡AsR′ species that have bulkier substituents (R′ = SiMe(SitBu3)2, SiiPrDis2, and NHC) occupy minima on the singlet potential energy surface, and they are both kinetically and thermodynamically stable. That is, the electronic and steric effects of bulky substituents play an important role in making molecules that feature an In≡As triple bond viable as a synthetic target. Moreover, two valence bond models are used to interpret the bonding character of the In≡As triple bond. One is model [A], which is best represented as . This interprets the bonding conditions for RIn≡AsR molecules that feature small ligands. The other is model [B], which is best represented as . This explains the bonding character of RIn≡PAsR molecules that feature large substituents.