Calculated properties and ring-chain rearrangements of triphosphirane (P3H3)

Andrea Deák, Monica Venter, A. Kálmán, L. Párkányí, Lajos Radics, Ionel Haiduc

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Ab initio quantum chemical calculations have been used to explore the P3H3 potential energy surface focussing on the ring-chain rearrangements of the three-membered ring in (PH)3 (1), the parent triphosphirane. Relative energies between stationary points were estimated using the QCISD(T)/6- 311G(d,p) method based on MP2/6-31G(d,p) geometries and corrected for zero- point contributions. Ring strain, proton affinities, ionization and excitation energies and heats of formation have been evaluated using larger basis sets, e.g. 6-311++G(3df,2p). The cyclic transtriphosphirane (1a) is the most stable P3H3 isomer and lies about 40 kJ/mol below the open-chain phosphanyldiphosphene (H2P-P=PH). The decrease of ring strain in threemembered rings when CH2 is replaced by PH is confirmed. Triphosphirane 1a is a virtually strain-free ring and even gains some stabilization relative to three separate P-P single bonds. The reduced ring strain also helps diminish the phosphorus inversion barrier to 224 kJ/mol compared to the monocyclic isomers of (CH2)(PH)2 and (CH2)2(PH). Compound 1a follows a pure ring-opening or a 1,2-hydrogen shift rather than a combined motion pathway, in fundamental contrast with corresponding processes of diphosphirane and phosphirane. This is due to the existence of an open-chain P3H3 phosphorane intermediate stabilized by allylic conjugation. The pericyclic ring-opening of 1a is the most favored process but the energy barrier in the gas phase is about 180 kJ/mol high. Electron density is largely delocalized within the three-membered P3 ring not only in the C(3v)- symmetric 1b (all-cis) but also in 1a (C(s)). The proton affinity of 1a is similar to that of PH3. The proton affinities decrease with n in cyclo- (CH3)(3-n)(PH)(n) and their values were obtained: PA(1a) = 777 ± 10, PA(diphosphirane) = 799 ±10 and PA(phosphirane) = 802 ± 10 kJ/mol. Heats of formation are evaluated as follows (ΔH°10 at 0 K in kJ/mol): 1a, 70 ±10; cyclo-(PH)2(PH2)+ (protonated 1a), 821 ±10; diphosphirane, 85 ±10; cyclo-(CH2)(PH)(PH2)+ (protonated diphosphirane), 814 ±10; phosphirane, 86 ±10; and protonated phosphirane, 812 ±10 kJ/mol. All P rings remain cyclic following ionization to the radical cations. Adiabatic ionization energies (IE(a)) are estimated as: 1a and diphosphirane, 9.3 ±0.3 eV and phosphirane 9.5 ±0.3 eV. The first UV absorption band shifts toward the longer wavelength region on going from phosphirane to 1a. The GIAO/B3LYP computed magnetic shieldings for 1a and related molecules reveal a clear relationship between the narrow bond angles in the rings and their unusually strong magnetic shielding. The similarity of the predicted 31P-NMR signals in 1a and its heteroanalog diphosphirane, (CH2)(PH)2, can be rationalized in terms of a compensation of the carbon-substituent effect (downfield shift) and the bond-bending effect imposed by the ring (upfield shift).

Original languageEnglish
Pages (from-to)103-112
Number of pages10
JournalEuropean Journal of Inorganic Chemistry
Issue number1
Publication statusPublished - 2000

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Magnetic shielding
Protons
Ionization potential
Isomers
Phosphoranes
Potential energy surfaces
Excitation energy
Energy barriers
Phosphorus
Ionization
Carrier concentration
Cations
Absorption spectra
Hydrogen
Carbon
Stabilization
Gases
Nuclear magnetic resonance
Wavelength
Molecules

Keywords

  • Ab initio calculations
  • Heterocycles
  • Ionization potentials
  • Phosphorus
  • Small ring systems

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Calculated properties and ring-chain rearrangements of triphosphirane (P3H3). / Deák, Andrea; Venter, Monica; Kálmán, A.; Párkányí, L.; Radics, Lajos; Haiduc, Ionel.

In: European Journal of Inorganic Chemistry, No. 1, 2000, p. 103-112.

Research output: Contribution to journalArticle

Deák, Andrea ; Venter, Monica ; Kálmán, A. ; Párkányí, L. ; Radics, Lajos ; Haiduc, Ionel. / Calculated properties and ring-chain rearrangements of triphosphirane (P3H3). In: European Journal of Inorganic Chemistry. 2000 ; No. 1. pp. 103-112.
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abstract = "Ab initio quantum chemical calculations have been used to explore the P3H3 potential energy surface focussing on the ring-chain rearrangements of the three-membered ring in (PH)3 (1), the parent triphosphirane. Relative energies between stationary points were estimated using the QCISD(T)/6- 311G(d,p) method based on MP2/6-31G(d,p) geometries and corrected for zero- point contributions. Ring strain, proton affinities, ionization and excitation energies and heats of formation have been evaluated using larger basis sets, e.g. 6-311++G(3df,2p). The cyclic transtriphosphirane (1a) is the most stable P3H3 isomer and lies about 40 kJ/mol below the open-chain phosphanyldiphosphene (H2P-P=PH). The decrease of ring strain in threemembered rings when CH2 is replaced by PH is confirmed. Triphosphirane 1a is a virtually strain-free ring and even gains some stabilization relative to three separate P-P single bonds. The reduced ring strain also helps diminish the phosphorus inversion barrier to 224 kJ/mol compared to the monocyclic isomers of (CH2)(PH)2 and (CH2)2(PH). Compound 1a follows a pure ring-opening or a 1,2-hydrogen shift rather than a combined motion pathway, in fundamental contrast with corresponding processes of diphosphirane and phosphirane. This is due to the existence of an open-chain P3H3 phosphorane intermediate stabilized by allylic conjugation. The pericyclic ring-opening of 1a is the most favored process but the energy barrier in the gas phase is about 180 kJ/mol high. Electron density is largely delocalized within the three-membered P3 ring not only in the C(3v)- symmetric 1b (all-cis) but also in 1a (C(s)). The proton affinity of 1a is similar to that of PH3. The proton affinities decrease with n in cyclo- (CH3)(3-n)(PH)(n) and their values were obtained: PA(1a) = 777 ± 10, PA(diphosphirane) = 799 ±10 and PA(phosphirane) = 802 ± 10 kJ/mol. Heats of formation are evaluated as follows (ΔH°10 at 0 K in kJ/mol): 1a, 70 ±10; cyclo-(PH)2(PH2)+ (protonated 1a), 821 ±10; diphosphirane, 85 ±10; cyclo-(CH2)(PH)(PH2)+ (protonated diphosphirane), 814 ±10; phosphirane, 86 ±10; and protonated phosphirane, 812 ±10 kJ/mol. All P rings remain cyclic following ionization to the radical cations. Adiabatic ionization energies (IE(a)) are estimated as: 1a and diphosphirane, 9.3 ±0.3 eV and phosphirane 9.5 ±0.3 eV. The first UV absorption band shifts toward the longer wavelength region on going from phosphirane to 1a. The GIAO/B3LYP computed magnetic shieldings for 1a and related molecules reveal a clear relationship between the narrow bond angles in the rings and their unusually strong magnetic shielding. The similarity of the predicted 31P-NMR signals in 1a and its heteroanalog diphosphirane, (CH2)(PH)2, can be rationalized in terms of a compensation of the carbon-substituent effect (downfield shift) and the bond-bending effect imposed by the ring (upfield shift).",
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TY - JOUR

T1 - Calculated properties and ring-chain rearrangements of triphosphirane (P3H3)

AU - Deák, Andrea

AU - Venter, Monica

AU - Kálmán, A.

AU - Párkányí, L.

AU - Radics, Lajos

AU - Haiduc, Ionel

PY - 2000

Y1 - 2000

N2 - Ab initio quantum chemical calculations have been used to explore the P3H3 potential energy surface focussing on the ring-chain rearrangements of the three-membered ring in (PH)3 (1), the parent triphosphirane. Relative energies between stationary points were estimated using the QCISD(T)/6- 311G(d,p) method based on MP2/6-31G(d,p) geometries and corrected for zero- point contributions. Ring strain, proton affinities, ionization and excitation energies and heats of formation have been evaluated using larger basis sets, e.g. 6-311++G(3df,2p). The cyclic transtriphosphirane (1a) is the most stable P3H3 isomer and lies about 40 kJ/mol below the open-chain phosphanyldiphosphene (H2P-P=PH). The decrease of ring strain in threemembered rings when CH2 is replaced by PH is confirmed. Triphosphirane 1a is a virtually strain-free ring and even gains some stabilization relative to three separate P-P single bonds. The reduced ring strain also helps diminish the phosphorus inversion barrier to 224 kJ/mol compared to the monocyclic isomers of (CH2)(PH)2 and (CH2)2(PH). Compound 1a follows a pure ring-opening or a 1,2-hydrogen shift rather than a combined motion pathway, in fundamental contrast with corresponding processes of diphosphirane and phosphirane. This is due to the existence of an open-chain P3H3 phosphorane intermediate stabilized by allylic conjugation. The pericyclic ring-opening of 1a is the most favored process but the energy barrier in the gas phase is about 180 kJ/mol high. Electron density is largely delocalized within the three-membered P3 ring not only in the C(3v)- symmetric 1b (all-cis) but also in 1a (C(s)). The proton affinity of 1a is similar to that of PH3. The proton affinities decrease with n in cyclo- (CH3)(3-n)(PH)(n) and their values were obtained: PA(1a) = 777 ± 10, PA(diphosphirane) = 799 ±10 and PA(phosphirane) = 802 ± 10 kJ/mol. Heats of formation are evaluated as follows (ΔH°10 at 0 K in kJ/mol): 1a, 70 ±10; cyclo-(PH)2(PH2)+ (protonated 1a), 821 ±10; diphosphirane, 85 ±10; cyclo-(CH2)(PH)(PH2)+ (protonated diphosphirane), 814 ±10; phosphirane, 86 ±10; and protonated phosphirane, 812 ±10 kJ/mol. All P rings remain cyclic following ionization to the radical cations. Adiabatic ionization energies (IE(a)) are estimated as: 1a and diphosphirane, 9.3 ±0.3 eV and phosphirane 9.5 ±0.3 eV. The first UV absorption band shifts toward the longer wavelength region on going from phosphirane to 1a. The GIAO/B3LYP computed magnetic shieldings for 1a and related molecules reveal a clear relationship between the narrow bond angles in the rings and their unusually strong magnetic shielding. The similarity of the predicted 31P-NMR signals in 1a and its heteroanalog diphosphirane, (CH2)(PH)2, can be rationalized in terms of a compensation of the carbon-substituent effect (downfield shift) and the bond-bending effect imposed by the ring (upfield shift).

AB - Ab initio quantum chemical calculations have been used to explore the P3H3 potential energy surface focussing on the ring-chain rearrangements of the three-membered ring in (PH)3 (1), the parent triphosphirane. Relative energies between stationary points were estimated using the QCISD(T)/6- 311G(d,p) method based on MP2/6-31G(d,p) geometries and corrected for zero- point contributions. Ring strain, proton affinities, ionization and excitation energies and heats of formation have been evaluated using larger basis sets, e.g. 6-311++G(3df,2p). The cyclic transtriphosphirane (1a) is the most stable P3H3 isomer and lies about 40 kJ/mol below the open-chain phosphanyldiphosphene (H2P-P=PH). The decrease of ring strain in threemembered rings when CH2 is replaced by PH is confirmed. Triphosphirane 1a is a virtually strain-free ring and even gains some stabilization relative to three separate P-P single bonds. The reduced ring strain also helps diminish the phosphorus inversion barrier to 224 kJ/mol compared to the monocyclic isomers of (CH2)(PH)2 and (CH2)2(PH). Compound 1a follows a pure ring-opening or a 1,2-hydrogen shift rather than a combined motion pathway, in fundamental contrast with corresponding processes of diphosphirane and phosphirane. This is due to the existence of an open-chain P3H3 phosphorane intermediate stabilized by allylic conjugation. The pericyclic ring-opening of 1a is the most favored process but the energy barrier in the gas phase is about 180 kJ/mol high. Electron density is largely delocalized within the three-membered P3 ring not only in the C(3v)- symmetric 1b (all-cis) but also in 1a (C(s)). The proton affinity of 1a is similar to that of PH3. The proton affinities decrease with n in cyclo- (CH3)(3-n)(PH)(n) and their values were obtained: PA(1a) = 777 ± 10, PA(diphosphirane) = 799 ±10 and PA(phosphirane) = 802 ± 10 kJ/mol. Heats of formation are evaluated as follows (ΔH°10 at 0 K in kJ/mol): 1a, 70 ±10; cyclo-(PH)2(PH2)+ (protonated 1a), 821 ±10; diphosphirane, 85 ±10; cyclo-(CH2)(PH)(PH2)+ (protonated diphosphirane), 814 ±10; phosphirane, 86 ±10; and protonated phosphirane, 812 ±10 kJ/mol. All P rings remain cyclic following ionization to the radical cations. Adiabatic ionization energies (IE(a)) are estimated as: 1a and diphosphirane, 9.3 ±0.3 eV and phosphirane 9.5 ±0.3 eV. The first UV absorption band shifts toward the longer wavelength region on going from phosphirane to 1a. The GIAO/B3LYP computed magnetic shieldings for 1a and related molecules reveal a clear relationship between the narrow bond angles in the rings and their unusually strong magnetic shielding. The similarity of the predicted 31P-NMR signals in 1a and its heteroanalog diphosphirane, (CH2)(PH)2, can be rationalized in terms of a compensation of the carbon-substituent effect (downfield shift) and the bond-bending effect imposed by the ring (upfield shift).

KW - Ab initio calculations

KW - Heterocycles

KW - Ionization potentials

KW - Phosphorus

KW - Small ring systems

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