Ab initio MO and DFT study of syn-sesquinorbornatrienyl dication and its isoelectronic boron analogueElectronic supplementary information (ESI) available: bond distances and bond angles of structures 6a, 6c, 7a and 7c calculated at the MP2/6-31+G* and B3LYP/6-31G* levels of theory (Table S1). See http://www.rsc.org/suppdata/nj/b4/b403802a/

Antol, Ivana; Glasovac, Zoran; Eckert‐Maksić, Mirjana

doi:10.1039/b403802a

Cited by 7 publications

(2 citation statements)

References 52 publications

(18 reference statements)

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“…A combination of approaches ii, iii, and iv leads, for example, to the heteroatom-free syn -sesquinorbornenylidene derivative syn - 34 . The bending of the framework is exo , exo as for the corresponding cation, the opposite as for syn -sesquinorbornene 30a. It represents the most stable alkyl carbene described in this article, since 27.1 kcal/mol (Figure ) is required for the isomerization through a vinyl shift.…”

Section: Methodsmentioning

confidence: 90%

The Nature and Extent of π-Stabilization within Foiled Carbenes

Mieusset

Brinker

2006

J. Am. Chem. Soc.

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B3LYP/6-311+G(d,p) computations of the stabilization energies, singlet-triplet energy gaps, and lowest transition states for a set of cyclic alkenylidenes were performed in order to find the strongest interactions between the C-C double bond and the carbene center. The results suggest that among the alkenylidenes investigated in this study, those with a norbornenylidene structure represent strongly stabilized carbenes with a reduced reactivity toward intermolecular reactions. Further stabilization is found when the double bond is electron-rich or pyramidalized. Thus, for the rearrangement of syn-34 to take place, an activation barrier of about 22 kcal/mol needs to be overcome. The inclination to undergo a retro-Skattebøl rearrangement, which to our knowledge has never been observed experimentally, is characteristic for highly stabilized foiled carbenes.

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Section: Methodsmentioning

confidence: 90%

The Nature and Extent of π-Stabilization within Foiled Carbenes

Mieusset

Brinker

2006

J. Am. Chem. Soc.

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“…The magnetic shielding calculations were performed within the GIAO (gauge-independent atomic orbitals) framework. , For 11 B, magnetic shieldings were calculated on the B3-LYP , and BP-86 , level of theory with the def2-TZVP basis set using the TURBOMOLE program package. Chemical shifts are referenced to BF 3 ·Et 2 O by using B 2 H 6 (δ(B 2 H 6 ) = 16.6 ppm vs BF 3 ·Et 2 O) as an external standard (σ BP‑86 (B 2 H 6 ) = 81.04 ppm, σ B3‑LYP (B 2 H 6 ) = 84.23 ppm). − 31 P chemical shifts were calculated with the B3-LYP functional and the def2-TZVP basis set. Chemical shifts were referenced to phosphoric acid (σ B3‑LYP = 274.31 ppm).…”

Section: Methodsmentioning

confidence: 99%

New Insights into Frustrated Lewis Pairs: Structural Investigations of Intramolecular Phosphane–Borane Adducts by Using Modern Solid-State NMR Techniques and DFT Calculations

et al. 2012

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Covalent bonding interactions between the Lewis acid and Lewis base functionalities have been probed in a series of "frustrated Lewis pairs" (FLPs) (mainly substituted vinylene linked intramolecular phosphane−borane adducts), using solid-state nuclear magnetic resonance techniques and accompanying DFT calculations. Both the 11 B NMR isotropic chemical shifts and nuclear electric quadrupolar coupling parameters turn out to be extremely sensitive experimental probes for such interactions, revealing linear correlations with boron−phosphorus internuclear distances. The principal component V zz of the 11

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Polar covalent apex‐base bonding in borapyramidanes probed by solid‐state NMR and DFT calculations

Luder,

Terefenko,

Sun

et al. 2024

Chemistry A European J

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Pyramidane molecules have attracted chemists for many decades due to their regular shape, high symmetry and their correspondence in the macroscopic world. Recently, experimental access to a number of examples has been reported, in particular the rarely reported square pyramidal bora[4]pyramidanes. To describe the bonding situation of the nonclassical structure of pyramidanes, we present solid‐state Nuclear Magnetic Resonance (NMR) as a versatile tool for deciphering such bonding properties for three now accessible bora[4]pyramidane and dibora[5]pyramidane molecules. 11B solid‐state NMR spectra indicate that the apical boron nuclei in these compounds are strongly shielded (around −50 ppm vs. BF3‐Et2O complex) and possess quadrupolar coupling constants of less than 0.9 MHz pointing to a rather high local symmetry. 13C−11B spin‐spin coupling constants have been explored as a measure of the bond covalency in the borapyramidanes. While the carbon‐boron bond to the −B(C6F5)2 substituents of the base serves as an example for a classical covalent 2‐center‐2‐electron (2c–2e) sp2‐carbon‐sp2‐boron σ‐bond with 1J(13C‐11B) coupling constants in the order of 75 Hz, those of the boron(apical)‐carbon(basal) bonds in the pyramid are too small to measure. These results suggest that these bonds have a strongly ionic character, which is also supported by quantum‐chemical calculations.

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Cited by 7 publications

References 52 publications

The Nature and Extent of π-Stabilization within Foiled Carbenes

The Nature and Extent of π-Stabilization within Foiled Carbenes

New Insights into Frustrated Lewis Pairs: Structural Investigations of Intramolecular Phosphane–Borane Adducts by Using Modern Solid-State NMR Techniques and DFT Calculations

Polar covalent apex‐base bonding in borapyramidanes probed by solid‐state NMR and DFT calculations

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