Borasilylenes in Focus: Topological Effects of Nitrogen Atoms by DFT
- PDF / 422,580 Bytes
- 7 Pages / 595.276 x 790.866 pts Page_size
- 11 Downloads / 188 Views
ORIGINAL PAPER
Borasilylenes in Focus: Topological Effects of Nitrogen Atoms by DFT Nastaran Abedini 1 & Mohammad Zaman Kassaee 1,2
&
Peter T. Cummings 2
Received: 22 July 2020 / Revised: 26 September 2020 / Accepted: 29 September 2020 # Springer Nature B.V. 2020
Abstract DFT calculations in combination with appropriate isodesmic reactions are employed to assess topological effects of nitrogens on thermodynamic parameters of novel mono-, di-, tri-, tetra-, and pentaaza-7-boratricyclo[1,1,1,01,7,07,3,07,5]hexa2-silylenes (1–20). Despite the enormous steric strain involved in their cubic structures, all our scrutinized singlet and triplet silylenes (1s-20s vs. 1t-20t, respectively) appear as minima on their energy surfaces, for showing singlet ground states. The highest stability (ΔEs−t) is achieved by 1,3,5-triaza-7-boratricyclo[1,1,1,01,7,07,3,07,5]hexa-2-silylene (11), where all the three nitrogens are bonded to the central boron atom. All of our silylenes show the same trend for their calculated ΔΕs−t and band gap (ΔΕHOMO−LUMO). Isodesmic reactions are employed to compare and contrast nucleophilicity (N), electrophilicity (ω), and heat of hydrogenation (ΔEH) for our 40 silylenes (1s-20s vs. 1t-20t). In fact, we introduce a novel generation of tridimensional silylenes which have the intrinsic potential of expanding the existing boundaries of semiconductors, cumulated multi-dentate ligands, etc.. Keywords Silylene . Stability . Nucleophilicity . Band gap . DFT
1 Introduction Silylenes are highly exotic sextet reactive intermediates, with R1-S̈ i-R2 formula, which have evolved to important chemical species [1]. They are either symmetric R1=R2, or antisymmetric R1≠R2, but intrinsically appear with singlet ground state [2–4]. The larger size of the valence orbitals of silicon decreases the electron-electron repulsion of the lone pair on Si, consequently increases the separation energy of electrons. Therefore, a silylene energetically prefers to be singlet ground state [5, 6]. The first stable silylene was synthesized by Denk et al. in 1994 [7]. Silylenes are applied in light-emitting diode (LED), electroluminescence (EL), silicon chemical vapor
Mohammad Zaman Kassaee is a visiting scholar (sabbatical). Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12633-020-00745-2) contains supplementary material, which is available to authorized users. * Mohammad Zaman Kassaee [email protected]; [email protected] 1
Chemistry Department, Tarbiat Modares University, Tehran 14115-175, Iran
2
Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37240, USA
deposition (CVD) processes, optics, electronics, and semiconductors [8-15]. Silylenes have an extremely reactive vacant 3p-orbital, with a rather inert lone pair that has a high s character. Substituents affect the ground state of silylenes [15–18]. pDonor and σ -acceptor amino groups stabilize singlet silylenes leading to their increased stability, which is portrayed by the increased
Data Loading...
