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Cyclonona‐3,5,7‐trienylidene and its Si, Ge, Sn, and Pb analogs versus their α‐halogenated derivatives at B3LYP and MP2 methods
Author(s) -
Koohi Maryam
Publication year - 2019
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.4013
Subject(s) - chemistry , singlet state , carbene , crystallography , isodesmic reaction , electrophile , divalent , conformational isomerism , ground state , computational chemistry , heteroatom , stereochemistry , density functional theory , molecule , atomic physics , catalysis , ring (chemistry) , organic chemistry , physics , excited state
Five sets of group 14 sextet cyclic unsaturated divalent species including carbenes ( 1 X ), silylenes ( 2 X ), germylenes ( 3 X ), stannylenes ( 4 X ), and plumbylenes ( 5 X ) are compared and contrasted at B3LYP/AUG‐cc‐pVTZ//B3LYP/6‐311 + G* and MP2/AUG‐cc‐pVTZ//MP2/6‐311 + G* levels of theory, where X = H, F, Cl, and Br. The scrutinized carbenes consisting of cyclonona‐3,5,7‐trienylidene ( 1 H ) and its 2,2,9,9‐tetrahalo derivatives ( 1 Cl , 1 Br ) appear as boat shaped minima except for 1 H which turns out as a boat shaped transition state for having a negative force constant. All of carbenes ( 1 H , 1 Cl , and 1 Br ) have triplet ground states except for 1 F . In contrast, all of the corresponding 2 X ‐ 5 X metallylenes appear as singlet boat shaped minima on their potential energy surfaces. Stability (estimated by Δ E s‐t , ie, energy gap between singlet [s] and triplet states) appear as a function of size and decreases by going down in group 14 column: 5 X > 4 X > 3 X > 2 X > 1 X . Exclusive of carbene set, within other four sets stability decreases by going down in group 17 column: Br > Cl > F > H. Hence, singlet 2,2,9,9‐tetrabromocyclonona‐3,5,7‐trienplumbylene, 5 Br , appears as the most stable sextet divalent with no tendency for dimerization. Comparison is extended to the structural parameters, band gap, nucleophilicity, electrophilicity, isodesmic reactions, and dimerization.