A density functional theory derived force field for the dicyano‐pyridinium methylide

Karzazi, Y.; Vergoten, G.; Surpateanu, Gheorghe

doi:10.1002/ejtc.59

Cited by 6 publications

(7 citation statements)

References 7 publications

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“…The analysis of the Cambridge Crystallographic Database System [4][5][6][7][8][9][10][11][12][13][14] shows that among 160 000 structures of organic and organometallic compounds, only nine structures corresponds to cycloimmonium ylides. Thus, it appears very important to increase the number of crystallographic structures resolved by X-ray diffraction in order to elucidate the spatial distribution between the carbanion and the heterocycle in cycloimmnium ylides.…”

Section: Scheme 1 Synthesis Scheme Of Ylide Imentioning

confidence: 99%

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A comparative X‐Ray diffraction study and MO AM1 semi‐empirical calculations on the 1‐carbethoxymethyl‐4 triazolium‐4′nitrobenzoyl‐2″,3″,4″ trinitrophenyl methylide

Karzazi¹,

Surpateanu²,

Vergoten³

1997

Elect J Theoret Chem

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SUMMARYThe crystal structure of the title compound, C20H15N7O11, has been determined using X-ray diffraction. The compound crystallizes in the triclinic system, space group P − 1 with cell dimensions a = 7.213(2)Å, b = 11.611(4)Å, c = 15.719(2)Å, α = 73.96• (2), β = 79.85• (2) and Z = 2. The structure has been refined to final R = 0.050 for 1695 reflections. The ylide carbon-pyridinium nitrogen bond distance is 1.441(2)Å. The refined structure was found to be non-planar. The plane of the pyridinium ring is rotated relative to the ylide carbanion plane by 39.47• . A comparative study with the AM1 semi-empirical method shows a good agreement with X-ray diffraction data. Indeed the standard deviations between the calculated and experimental values are 0.038Å and 0.056• for bond lengths and bond angles, respectively.

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Section: Scheme 1 Synthesis Scheme Of Ylide Imentioning

confidence: 99%

“…The AM1 semi-empirical method is able to reproduce the experimental observables and ab initio results with good accuracy [15]. The AM1 calculations were performed using the MOPAC program [16] implemented in the SYBYL software package [17] on a Silicon Graphics 4D/340VGX workstation.…”

Section: Scheme 1 Synthesis Scheme Of Ylide Imentioning

confidence: 99%

A comparative X‐Ray diffraction study and MO AM1 semi‐empirical calculations on the 1‐carbethoxymethyl‐4 triazolium‐4′nitrobenzoyl‐2″,3″,4″ trinitrophenyl methylide

Karzazi¹,

Surpateanu²,

Vergoten³

1997

Elect J Theoret Chem

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“…In a previous study [6] we have determined by ab initio calculation, that in the stability of cycloimmonium ylides the resonance interaction between the aromatic ring cloud and the carbanion is a principal factor. We use the REDONG program [7] in order to carry out vibrational analysis for internal coordinates starting from the DMOL [8] ab initio calculation of vibrational frequencies.…”

Section: Force Field Implementationmentioning

confidence: 99%

A quantum mechanical force field for amidocyano‐pyridinium methylide. Force field transferability to the cycloimmonium ylides

Karzazi

Vergoten

Surpateanu³

1997

Elect J Theoret Chem

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SUMMARYAn ab initio force field for the amidocyano-pyridinium methylide has been deduced from calculations based on density functional theory. The force constants derived from these ab initio calculations are used in order to establish an empirical force field for cycloimmonium ylides, where the transferability of the derived force constants was tested. In this way, we proposed a new atom-type for the ylidic carbon atom and for the cyclic nitrogen atom. The goal of this force field is to provide good quality geometries for cycloimmonium ylide molecules by energy minimization. The predicted structures for dicyano-pyridinium methylide, amidocyano-pyridinium methylide and the pyridinium cation using the Tripos force field with parameters established by density functional ab initio calculations were in good agreement with those of the experimental X-ray diffraction data. A general harmonic parameterization for the cycloimmonium ylides consistent with the available molecular mechanics models has been proposed. This report points out the importance of the ab initio force field availability to predict the structures of the cycloimmonium ylides. This study also includes a full conformational analysis.

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“…Cycloimmonium ylides 1, 2, obtained from various synthetic methods, form a well‐known class of zwitteronic compounds that display interesting chemical behavior 3–5. A representative compound of this class of ylides is the pyridinium dicyanomethylide (PDCM), shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…A representative compound of this class of ylides is the pyridinium dicyanomethylide (PDCM), shown in Figure 1. Although this type of ylide is investigated from various experimental and theoretical points of view 4, 5, the possibility of 3‐electron‐2‐center bonding has not been explored.…”

Section: Introductionmentioning

confidence: 99%

Three‐electron two‐center bonding in cycloimmonium ylides

Karafiloglou

Surpateanu

2004

Int J of Quantum Chemistry

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ABSTRACT:We explore the possibility that a 3-electron-2-center bonding exists in cycloimmonium ylides. To detect this bonding in a polyatomic system, 3-electron-1-hole density operators, characterizing a Pauling 3-electron bond, are used in the framework of second quantization formalism. The weights of 3-electron resonance structures are calculated and compared with the weights of 2-electron structures for the ylide bond of pyridinium dicyanomethylide; the correlations of (12) and (1) electronic events, involved in the 3-electron resonance structures, are also investigated. The calculations are performed in various approximation levels, and both orthogonal and nonorthogonal natural atomic orbitals are adopted. All calculations show that a 3-electron bond exists between N and C atoms of ylide bond, but this bonding is not extended in C atoms of the pyridinium group. The interactions of ␣,␤ electrons (at the configuration interaction [CI] level) increase the localization of electrons, the weights of 3-electron resonance structures, and thus the probability for 3-electron bonding.

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A density functional theory derived force field for the dicyano‐pyridinium methylide

Cited by 6 publications

References 7 publications

A comparative X‐Ray diffraction study and MO AM1 semi‐empirical calculations on the 1‐carbethoxymethyl‐4 triazolium‐4′nitrobenzoyl‐2″,3″,4″ trinitrophenyl methylide

A comparative X‐Ray diffraction study and MO AM1 semi‐empirical calculations on the 1‐carbethoxymethyl‐4 triazolium‐4′nitrobenzoyl‐2″,3″,4″ trinitrophenyl methylide

A quantum mechanical force field for amidocyano‐pyridinium methylide. Force field transferability to the cycloimmonium ylides

Three‐electron two‐center bonding in cycloimmonium ylides

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