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Prediction and Characterization of Alkaline‐Earth (M=Be, Mg, Ca, Sr, and Ba) Metallacyclopentadienes and Relevant Derivatives
Author(s) -
Sun Zhi,
Launder Andrew M.,
Schaefer Henry F.
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201601911
Subject(s) - antiaromaticity , thermochemistry , chemistry , characterization (materials science) , alkaline earth metal , natural bond orbital , cyclopentadiene , ring (chemistry) , ring strain , resonance (particle physics) , computational chemistry , aromaticity , density functional theory , alkali metal , inorganic chemistry , molecule , materials science , organic chemistry , nanotechnology , atomic physics , physics , catalysis
Alkaline‐earth metallacyclopentadienes are an active area of research in synthetic chemistry, notable for their roles as precursors of key cyclopentadiene derivatives. However, experimental characterization is limited due to their challenging synthesis and subsequent isolation. Herein, we report systematic theoretical studies of MC 4 H 4 (M=Be, Mg, Ca, Sr, Ba) rings and experimentally relevant complexes. Benchmarking against CCSD(T) and experiment shows reasonable performance for the B3LYP, BP86, and M06‐2X density functionals in predicting the equilibrium geometries, thermochemistry, and vibrational spectra of these species. NICS indices and extra cyclic resonance energies confirm that the compounds in question possess antiaromatic character. For both the bare MC 4 H 4 rings and larger complexes, the Be‐containing compounds were found to be the most strongly bound species. Such viability is explained via ring strain, electron densities, natural bond orders, and orbital analyses. Given that the second least viable Mg complex has been reported in recent experiments, synthesis and characterization of the other group IIA analogs are anticipated.