Aromatic Phosphorus Heterocycles

Nyulászi, L.; Benkő, Z.

doi:10.1007/7081_2008_6

Cited by 7 publications

(9 citation statements)

References 301 publications

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“…At the same time, the parent 8π-electron pentalene has by far eluded all synthetic efforts. The aromaticity of phosphorus heterocycles has been the subject of systematic and thorough investigations for the past decade . A relation may also be found between 1 and unusual heterocyclic compounds containing four-membered planar rings (C–P–Si–P and Si–P–Si–P) with two-coordinate phosphorus atoms .…”

Section: Resultsmentioning

confidence: 99%

N,N′-Fused Bisphosphole: Heteroaromatic Molecule with Two-Coordinate and Formally Divalent Phosphorus. Synthesis, Electronic Structure, and Chemical Properties

et al. 2014

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The reduction of 6,12-dichloro-1,2,3,4,7,8,9,10-octahydro-6H,12H-[1,2,3]benzodiazaphospholo[2,1-a][1,2,3]benzodiazaphosphole (3) by metallic magnesium in tetrahydrofuran (THF) affords the N,N'-fused bisphosphole 1 in 92% yield. The compound reveals a novel type of 10π-electron heteroaromatic system [NICS(0) = -11.4], containing a two-coordinate and formally divalent phosphorus atom. Compound 1 possesses a much higher coordination activity than many other diazaphospholes. This is caused by a novel type of complexation to a metal ion wherein the lone phosphorus pairs are not involved in metal coordination. Instead, the 10π-electron heteroaromatic system provides two electrons for P → M bond formation. Polarization of the ligand results in the formation of extended molecular associates or cluster compounds. Complexes of 1 with mercury dichloride [{(1)3HgCl}2(μ6-Cl)](+)Cl(-) (7) and tin dichlorides [1·SnCl2(PhMe solvate)] (8a) and [1·SnCl2] (8b) are, in fact, supramolecular in nature, containing multiple intermolecular short contacts. Crystals of complex 8a containing short Sn···Sn packing interactions were converted reversibly to metallic tin after workup with THF. The simple mixing of 1 and 3 (1:1) gave a P-P bridging dimeric species prone to easy dissociation. The addition of GeCl2(diox) to the equimolar mixture of 1 and 3 shifted the equilibrium to the formation of a poorly soluble salt-like dimer 6, which is, in fact, a stacked 18π-electron dication having a through-space delocalization of π electrons.

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Section: Resultsmentioning

confidence: 99%

N,N′-Fused Bisphosphole: Heteroaromatic Molecule with Two-Coordinate and Formally Divalent Phosphorus. Synthesis, Electronic Structure, and Chemical Properties

et al. 2014

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“…In an attempt to correlate the observed reactivity of the different phosphole P(V) derivatives with their electronic properties, we carried out DFT calculations at the B3LYP-D3/6-31G(d) level of theory (see SI) to determine the HOMO-LUMO gaps and the NICS(0) values (Table 6). Phospholes 1 are often considered as weakly aromatic compounds [15][16][17] and this is reflected in the small negative values for the NICS(0) (-2.83, -3.09, and -2.62 ppm for 1a, 1b, and 1c, respectively). In contrast, phosphole P=O compounds 2 tend towards anti-aromatic systems with positive NICS(0) values (1.41, 1.79, and 1.22 ppm for 2a, 2b, and 2c, respectively), which makes them more reactive towards further dimerization reactions [18].…”

Section: Dft Calculationsmentioning

confidence: 99%

“…Phospholes have found widespread interest in many areas, including catalysis, material sciences, and biological applications, due to the ready modification of their electronic, steric, and physicochemical properties and their different coordination modes to metals [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Among the various possibilities, changing the substituents or the substitution pattern on the phosphole ring or on the phosphorus atom can modify the stability and the aromaticity of these heterocycles [15][16][17]. A major change is often induced by oxidation of the weakly aromatic P(III) compounds to non-or anti-aromatic P(V) derivatives employing oxygen/peroxides, sulphur, or selenium [18].…”

Section: Introductionmentioning

confidence: 99%

[4+2] versus [2+2] Homodimerization in P(V) Derivatives of 2,4-Disubstituted Phospholes

Bousrez

Nicolas

Martinez

et al. 2019

Heteroatom Chemistry

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Phosphole P(V) derivatives are interesting building blocks for various applications from ligand synthesis to material sciences. We herein describe the preparation and characterisation of new 2,4-disubstituted oxo-, thiooxo-, and selenooxophospholes. The nature of the substituents on the phosphole ring determines the reactivity of these compounds towards homodimerization reactions. Aryl and trimethylsilyl substituted oxophospholes undergo selective [4+2] dimerization, whereas, for thiooxo- and selenooxophospholes, light-induced, selective [2+2] head-to-head dimerization occurs in the case of aryl substituents. DFT calculations provide some insights on these differences in reactivity.

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“…The analogy turned out to be so prolific that besides a few research papers [29,30,31,32,33] on this theme, a monograph with the title, “Phosphorus: The Carbon Copy” [34] has been published. The effect of the exchange of the CH moiety with phosphorus atom (CH/P exchange) on the aromaticity of the carbocyclic rings has been discussed in two recent reviews [35,36], which include detailed experimental and theoretical discussion of the three- to six-membered rings having one or more phosphorus atoms. It was concluded that due to the small angle at the P atom (ca.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mono- and Poly-CH/P Exchange(s) on the Aromaticity of the Tropylium Ion

Puri

2016

Molecules

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Abstract:In view of the fact that the phosphorus atom in its low co-ordination state (coordination numbers 1 and 2) has been termed as the carbon copy, there have been attempts to investigate, theoretically as well as experimentally, the effect of the exchange(s) of CH-moiety with phosphorus atom(s) (CH/P) on the structural and other aspects of the classical carbocyclic and heterocyclic systems. Tropylium ion is a well-known non-benzenoid aromatic system and has been studied extensively for its aromatic character. We have now investigated the effect of mono-and poly-CH/P exchange(s) on the aromaticity of the tropylium ion. For this purpose, the parameters based on the geometry and magnetic properties, namely bond equalization, aromatic stabilization energies (ASE), Nucleus-Independent Chemical Shift (NICS) values, (NICS(0), NICS(1), NICS(1) zz ), proton nucleus magnetic resonance ( 1 H-NMR) chemical shifts, magnetic susceptibility exaltation and magnetic anisotropic values of mono-, di-, tri-and tetra-phosphatropylium ions have been determined at the Density Functional Theory (DFT) (B3LYP/6-31+G(d)) level. Geometry optimization reveals bond length equalization. ASEs range from −46.3 kcal/mol to −6.2 kcal/mol in mono-and diphospha-analogues which are planar. However, the ions having three and four phosphorus atoms lose planarity and their ASE values approach the values typical for non-aromatic structures. Of the three NICS values, the NICS(1) zz is consistently negative showing aromatic character of all the systems studied. It is also supported by the magnetic susceptibility exaltations and magnetic anisotropic values. Furthermore, 1 H-NMR chemical shifts also fall in the aromatic region. The conclusion that mono-, di-, tri-and tetra-phosphatropylium ions are aromatic in nature has been further corroborated by determining the energy gap between the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) (HOMO − LUMO gap), which falls in the range, ca. 3 × 10 −19 -9 × 10 −19 J. The systems having more than four phosphorus atoms are not able to sustain their monocyclic structure.

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Aromatic Phosphorus Heterocycles

Cited by 7 publications

References 301 publications

N,N′-Fused Bisphosphole: Heteroaromatic Molecule with Two-Coordinate and Formally Divalent Phosphorus. Synthesis, Electronic Structure, and Chemical Properties

N,N′-Fused Bisphosphole: Heteroaromatic Molecule with Two-Coordinate and Formally Divalent Phosphorus. Synthesis, Electronic Structure, and Chemical Properties

[4+2] versus [2+2] Homodimerization in P(V) Derivatives of 2,4-Disubstituted Phospholes

Effect of Mono- and Poly-CH/P Exchange(s) on the Aromaticity of the Tropylium Ion

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Aromatic Phosphorus Heterocycles

Cited by 7 publications

References 301 publications

N,N′-Fused Bisphosphole: Heteroaromatic Molecule with Two-Coordinate and Formally Divalent Phosphorus. Synthesis, Electronic Structure, and Chemical Properties

N,N′-Fused Bisphosphole: Heteroaromatic Molecule with Two-Coordinate and Formally Divalent Phosphorus. Synthesis, Electronic Structure, and Chemical Properties

[​4+2] versus [​2+2] Homodimerization in P(V) Derivatives of 2,4-Disubstituted Phospholes

Effect of Mono- and Poly-CH/P Exchange(s) on the Aromaticity of the Tropylium Ion

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[4+2] versus [2+2] Homodimerization in P(V) Derivatives of 2,4-Disubstituted Phospholes