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Cooperative Donor–Acceptor Interactions in Stabilizing Carbene‐Borane and Carbene‐Alane Compounds: A Theoretical Insight
Author(s) -
Dutta Sayan,
De Sriman,
Bose Sanjoy,
Mahal Eti,
Koley Debasis
Publication year - 2020
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201901163
Subject(s) - carbene , chemistry , natural bond orbital , borane , boranes , valence bond theory , computational chemistry , acceptor , density functional theory , valence (chemistry) , crystallography , molecular orbital , organic chemistry , molecule , catalysis , boron , physics , condensed matter physics
Density functional theory calculations have been performed to elucidate the electronic structure and bonding scenario in various carbene‐borane ( L BX₃ ) and carbene‐alane ( L AlX₃ ) compounds (X = ‐H, ‐Me, ‐Cl, ‐Ph, ‐C 6 F 5 ). We have performed extended transition state (ETS) analysis to reveal the nature of the donor–acceptor bonds ( C c arb –E; E = B, Al) and also for the assessment of the intrinsic donor–acceptor strength in this class of compounds. Our computations suggest that the C c arb –Al bonds in all the L AlX₃ adducts have substantially higher electrostatic nature than covalent character. Conversely, the nature of the C c arb –B bonds in L BX₃ have a strong dependence on the electronic nature of both carbene and borane. Moreover, unlike alanes in L AlX₃ , the intrinsic Lewis acid strength of the boranes in L BX₃ has a strong dependence on the electronic nature of the carbenes. We have also explored the correlation of the interaction energies (Δ E int ) with various bonding parameters i.e., geometrical and Natural bond orbital (NBO) parameters of L EH₃ . Furthermore, natural orbital for chemical valence (NOCV) calculations are performed to have a qualitative understanding of the relative σ‐donating and π‐accepting abilities of the carbenes in L EH₃ . Additionally, we have investigated the abilities of carbenes to activate the B–H bonds in BH 3 and pinacolborane. ETS analysis shows a strong dependence of the B–H activation barriers on the distortion energies of both carbene and borane fragments.