The effect of substituents on the stability of triply bonded galliumantimony molecules: a new target for synthesis

Abstract

The effect of substitution on the potential energy surfaces of RGa[triple bond, length as m-dash]SbR (R = F, OH, H, CH, SiH, SiMe(SitBu), SiiPrDis and NHC) is studied using density functional theory (M06-2X/Def2-TZVP, B3PW91/Def2-TZVP and B3LYP/LANL2DZ + dp). The computational results show that all of the triply bonded RGa[triple bond, length as m-dash]SbR molecules have a preference for a bent geometry (i.e., ∠RGaSb ≈ 180° and ∠GaSbR ≈ 90°), which can be described using a valence bond model. The theoretical results show that because RGa[triple bond, length as m-dash]SbR has smaller electropositive groups, it could be both kinetically and thermodynamically stable and may be experimentally detectable. However, these theoretical results predict that the triply bonded R'Ga[triple bond, length as m-dash]SbR' molecules that have bulkier groups (R' = SiMe(SitBu), SiiPrDis, and NHC) are kinetically stable. In other words, both the electronic and the steric effects of bulkier substituent groups mean that it should be possible to experimentally isolate triply bonded RGa[triple bond, length as m-dash]SbR molecules in a stable form.

Is It Possible To Prepare and Stabilize Triple-Bonded Thallium≡Antimony Molecules Using Substituents?

“…Accordingly, the above theoretical analyses demonstrate that the triple-bonded RTl≡SbR compounds bearing the small ligands should not be detected experimentally as well as isolated in the laboratory, even in a low-temperature inert matrix. This theoretical conclusion is the same as in the previous cases found for RB≡SbR, 72 RAl≡SbR, 73 RGa≡SbR, 74 and RIn≡SbR 75 systems bearing small groups (R). In consequence, all of these theoretical observations strongly suggest that no matter what kind of electronegativity for the small ligands (R) are attached, the triple-bonded RE 13 ≡SbR molecules cannot exist in the normal conditions.…”

“…We have used the DFT computations to theoretically design substituted RE 13 SbR molecules that feature an E 13 Sb triple bond, which can be detected and characterized in the experiments. From the comparisons between this work (RTlSbR) and other previous studies (RBSbR, 72 RAlSbR, 73 RGaSbR, 74 and RInSbR 75 ), several major conclusions can be drawn:…”

“…We have used the DFT computations to theoretically design substituted RE 13 SbR molecules that feature an E 13 Sb triple bond, which can be detected and characterized in the experiments. From the comparisons between this work (RTlSbR) and other previous studies (RBSbR, RAlSbR, RGaSbR, and RInSbR), several major conclusions can be drawn: For the triple-bonded RE 13 SbR molecules bearing the small substituents, our theoretical evidences reveal that they should not be observable in the experiments. Our theoretical observations suggest that only the sterically bulky ligands (R′) can greatly stabilize the triple-bonded R′E 13 SbR′ molecules from the kinetic viewpoint. Nevertheless, our theoretical results demonstrate that the triple bond between the E 13 and antimony elements in the acetylene-like R′E 13 SbR′ species is quite weak. Its bond order is theoretically estimated to be slightly above 2.0. The reason for having such a weak E 13 Sb triple bond is simple: the atomic sizes as well as the electronegativity values for E 13 and Sb are different because they belong to different rows of the periodic table having different principal quantum numbers.…”

The First Fused N‐Heterocyclic Imidazole Pyridine Selones and Their Coordination Ability Towards Bismuth(III) Salts

“…In this remarkable diatomic compound, a pair of main group elements are trapped between two neutral donor NHC ligands. Thus the exciting chemistry of bis‐element lighter main‐group metalloid or metal derivatives is rapidly being explored . Unlike the lighter main‐group metalloid or metal derivatives, the NHC supported heavier main group compounds are limited due to the strong polar nature of the bond between carbene carbon and heavier main group elements .…”

“…Thus the exciting chemistry of bis‐element lighter main‐group metalloid or metal derivatives is rapidly being explored . Unlike the lighter main‐group metalloid or metal derivatives, the NHC supported heavier main group compounds are limited due to the strong polar nature of the bond between carbene carbon and heavier main group elements . As a result, only a few structurally characterized carbene supported bismuth(III), [7a], [7b], [7c] and bismuth(I)[7d] compounds have been isolated in the past twenty‐six years.…”