Substituent effects on the stability of cyclic - unsaturated remote N-heterocyclic Hammick carbenes using density functional theory

Söğütlü, İnci; Soltanzadeh, Mehdi; Mert, Handan; Mert, Nihat; Vessally, Esmail

doi:10.1016/j.molstruc.2020.129821

Cited by 10 publications

(3 citation statements)

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“…[3] Henceforth, to make an isolated stable NHGes, from two thermodynamic and kinetic view points, enough stabilization of the reactive vacant p-orbital is necessary. [4][5][6][7] The synthesis of the smallest cyclic NHGe I by Veith was obligated to electron donating from the adjacent nitrogen atoms and the steric hindrance provided by tert-butyl groups via thermodynamic and kinetic stabilization, respectively (Scheme 1). [8] If the resulted steric hindrance from substituting is insufficient, the germylene will undergo selfoligomerization, causing to the corresponding polymer, oligomer, or dimer isomer.…”

Section: Introductionmentioning

confidence: 99%

“…In this approach, one may find it fascinating to bring together the stabilizing mesomeric effects of fused adjacent heterocyclic with the steric protection of bulky substituted adjacent carbon atoms as germapyridine in same structure. Following our theoretical quest for group 14 divalent species, [1][2][3][4][5][6][7] the present survey is intending to show substituent effects of N, and P-heteroatoms on stability and reactivity of Hammick NHGes (Scheme 2).…”

Section: Introductionmentioning

confidence: 99%

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Substituent effects on the stability of N‐heterocyclic germylenes using density functional theory

Liu

Ahmadi

2021

J of Physical Organic Chem

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The effects of one and two fused six-membered heterocyclic rings on properties of novel singlet and triplet germylenes are studied, at density functional theory (DFT). The aim of the present work is to recognize the influence of nitrogen and phosphorus heteroatoms along with germylene center (GeC) on the stability, band gap, polarity, polarizability, electrophilicity, nucleophilicity, and charge. Irrespective of ortho or para organization, fusion of one pyridine and phosphinine ring causes more vibration frequency, stabilizing influence, and polarizability than two fused ones. The natural bond orbital (NBO) analysis of one fused germylenes displays covalent bonds with different powers between nitrogen and phosphorus heteroatoms with germylene center. They show different occupancy number for lone pair on the heteroatoms at ortho or para position. Also, because of dissimilar interactions of LP N8 !σ * C3-Ge16 , σ C3-Ge16 !σ * C2-N6 , LP P16 !σ * C3-Ge15 , and σ C3-Ge15 !σ * C2-P16 , they have different stabilization energy (E (2) ). There is a good consistency between singlet-triplet energy separation (ΔE s-t = E t -E s ) and E (2) values. The stability based on ΔE s-t and E (2) values of para-one fused germapyridines is more than the ortho-ones.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Substituent effects on the stability of N‐heterocyclic germylenes using density functional theory

Liu

Ahmadi

2021

J of Physical Organic Chem

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“…[16][17][18][19] A recent survey has probed on effects of pyridine-4-ylidene and abnormal pyridine derivatives on the thermodynamic and kinetic features of the resulted NHCs. [20][21][22][23] The most stability is found by pyridine-4-ylidene, while the least stability is established by NHC situated among two nitrogen heteroatoms of two fused rings, in "W" arrangement. Following our quest for more stable NHCs, now, we compare and contrast the substitution effects of pyridine and phosphinine rings on novel para−silapyridine, at density functional theory (Scheme 1).…”

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confidence: 99%

Characterization of novel pyridine‐derived N‐heterocyclic silylenes via density functional theory perspective

Hassanpour

Heravi

Rahmani

et al. 2021

J Chinese Chemical Soc

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We theoretically searched new derivatives of N‐heterocyclic silylenes (NHSis) by substituting of pyridine and phosphinine rings, compared to the reference carbenes (N‐heterocyclic carbenes—NHCs) including benzopyridine‐4‐ylidene (1) and dibenzopyridine‐4‐ylidene (2), at M06‐2X/AUG‐cc‐pVTZ and B3LYP/AUG‐cc‐pVTZ. Regardless of how organized NHSis are, fusion of 1 six‐membered ring leads to more vibration frequency (υmin), stabilizing effect, and polarizability than 2 six‐membered rings. In all cases, singlet (3s‐10s) and triplet (3t‐10t) NHSis emerge as ground state, showing more stability of singlet states than their corresponding triplet congeners. From thermodynamic and kinetic viewpoints, the scrutinized singlet NHSis show more stability than the parent singlet NHCs (1s and 2s), but the studied triplet NHSis exhibit less stability than triplet NHCs (1t and 2t). Regarding the orientation of silylenic center and nitrogen or phosphor heteroatoms of fused rings, the stabilizing energy for para−fused rings is more than ortho ones. The most stability is confirmed by one para−substituted pyridine NHSi (singlet‐triplet energy difference; ΔΕs‐t = 47.3 and band gap; ΔEHOMO‐LUMO = 85.0 kcal/mol; highest occupied molecular orbital [HOMO] and lowest unoccupied molecular orbital [LUMO]) and the least stability is demonstrated by two substituted benzene NHC (ΔΕs‐t = 11.9 and ΔEHOMO‐LUMO = 58.6 kcal/mol). In contrast to pure NHCs, triplet NHSis (3t‐10t) show lower ΔΕHOMO‐LUMO, higher nucleophilicity, lower electrophilicity, and lower chemical hardness than their corresponding singlet states (3s‐10s).

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Substituent effects of fused Hammick germylenes: Estimating the stability and reactivity using density functional theory

Elveny

Alrazzak

Aljeboree

et al. 2021

J of Physical Organic Chem

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In this theoretical survey, we compared and contrasted the substituent influences on stability, aromaticity, band gap, atomic charge distribution, and reactivity of 54 singlet and triplet fused Hammick germylenes derived from germabenzopyridine-4-ylidene as well as the synthesized five-and sixmembered ones by Herrmann and Driess, respectively. Investigations show (1) the lowest and the highest singlet-triplet energy difference (ΔΕ s-t ) is demonstrated by fusion of two phosphole rings and two furan rings in orthopositions (35.6 and 253.6 kJ/mol, respectively) compared with those of the synthesized germylenes (208.8 and 179.9 kJ/mol, respectively). (2) Whereas fusion of benzene, pyridine, phosphinine, and phosphole rings thermodynamically destabilizes the corresponding germylenes, fusion of pyrrole, furan, and thiophene rings stabilizes the corresponding germylenes. (3) The tendency of substituent influences in number and size of rings is arranged by two fivemembered rings > one five-membered rings > one six-membered rings > two six-membered rings. (4) While pyrrole, furan, and thiophene rings kinetically stabilize the corresponding germylenes, other rings destabilize their germylenes with respect to germapyridine-4-ylidene and the isolated germylene's Driess. (5) All singlet Hammick germylenes reveal lower nucleophilicity and softness, also higher electrophilicity, chemical potential, and global hardness than their scrutinized triplet states. (6) We are waiting for experimental testing and verifications to fuse heterocyclic rings to the germapyridine-4-ylidene's plane in a favorable spatial position to act not only as π-electron giver but also σ-electron receiver.

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Substituent effects on the stability of cyclic - unsaturated remote N-heterocyclic Hammick carbenes using density functional theory

Cited by 10 publications

References 50 publications

Substituent effects on the stability of N‐heterocyclic germylenes using density functional theory

Substituent effects on the stability of N‐heterocyclic germylenes using density functional theory

Characterization of novel pyridine‐derived N‐heterocyclic silylenes via density functional theory perspective

Substituent effects of fused Hammick germylenes: Estimating the stability and reactivity using density functional theory

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