Azaphosphinines and their derivatives

McNeill, J. Nolan; Bard, Jeremy P.; Johnson, Darren W.; Haley, Michael M.

doi:10.1039/d3cs00737e

Cited by 5 publications

(3 citation statements)

References 133 publications

(263 reference statements)

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“…In S 0 , there is a minute increase in the aromaticity when going from 10 to 12 according to MCI, in line with earlier findings based on NICS, ,− but in the lowest 3 n ,π* state, there is instead a minute decrease (Figure A). The MCI( 3 n ,π*) tot values of 10 – 12 are similar to those of 1 and 2 (Figure A); however, their residuals (with MCI( 3 n ,π*) tot at 42–47% of the MCI(S 0 ) values) tend toward antiaromatic character whereby they resemble 1 more than 2 .…”

Section: Resultssupporting

confidence: 90%

The n,π* States of Heteroaromatics: When are They the Lowest Excited States and in What Way Can They Be Aromatic or Antiaromatic?

Proos Vedin,

Escayola,

Radenković

et al. 2024

J. Phys. Chem. A

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Heteroaromatic molecules are found in areas ranging from biochemistry to photovoltaics. We analyze the n,π* excited states of 6π-electron heteroaromatics with in-plane lone pairs (n σ , herein n) and use qualitative theory and quantum chemical computations, starting at Mandado's 2n + 1 rule for aromaticity of separate spins. After excitation of an electron from n to π*, a (4n + 2)π-electron species has 2n + 2 π α -electrons and 2n + 1 π β -electrons (or vice versa) and becomes π α -antiaromatic and π β -aromatic. Yet, the antiaromatic π α -and aromatic π β -components seldom cancel, leading to residuals with aromatic or antiaromatic character. We explore vertically excited triplet n,π* states ( 3 n,π*), which are most readily analyzed, but also singlet n,π* states ( 1 n,π*), and explain which compounds have n,π* states with aromatic residuals as their lowest excited states (e.g., pyrazine and the phenyl anion). If the π β -electron population becomes more (less) uniformly distributed upon excitation, the system will have an (anti)aromatic residual. Among isomers, the one that has the most aromatic residual in 3 n,π* is often of the lowest energy in this state. Five-membered ring heteroaromatics with one or two N, O, and/or S atoms never have n,π* states as their first excited states (T 1 and S 1 ), while this is nearly always the case for six-membered ring heteroaromatics with electropositive heteroatoms and/or highly symmetric (D 2h ) diheteroaromatics. For the complete compound set, there is a modest correlation between the (anti)aromatic character of the n,π* state and the energy gap between the lowest n,π* and π,π* states (R 2 = 0.42), while it is stronger for monosubstituted pyrazines (R 2 = 0.84).

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Section: Resultssupporting

confidence: 90%

The n,π* States of Heteroaromatics: When are They the Lowest Excited States and in What Way Can They Be Aromatic or Antiaromatic?

Proos Vedin,

Escayola,

Radenković

et al. 2024

J. Phys. Chem. A

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“…7 The majority of currently reported phosphorus/nitrogen containing heterocycles are based on either five-or six-membered rings. 8 Sevenmembered rings containing both phosphorus and nitrogen and comparatively scarce. The most common approach for preparing seven-membered P/N rings relies on the condensation of amines with halophosphine derivatives, with concomitant release of HCl, which necessarily affords products with direct P-N bonds.…”

Section: Introductionmentioning

confidence: 99%

Accessing Five- and Seven-Membered Phosphorus-Based Heterocycles via Cycloaddition Reactions of Azophosphines

Calder,

Male,

Jupp

2024

Preprint

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Heterocycles containing both phosphorus and nitrogen have seen increasing use in recent years in luminescent materials, coordination chemistry and building blocks for inorganic polymers, yet their chemistry is currently dominated by five- and six-memberd derivatives. Seven-membered P/N heterocycles are comparatively scarce and lack general, high yielding syntheses. We explore the synthesis and characterisation of 1,2,5-diazaphosphepines from azophosphines. The mechanism has been probed in detail with both computational and experimental studies supporting a stepwise mechanism to form a five-membered ring, and subsequent ring expansion to the diazaphosphepine. Regioselective synthesis of five- and seven-membered rings is possible using asymmetric alkynes. The Lewis acidic borane B(C6F5)3 could either catalyse the formation of the seven-membered ring (iPr derivative) or trap out a key intermediate via a frustrated Lewis pair (FLP) mechanism (tBu derivative).

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“…Five-membered nitrogen-containing phosphorus heterocycles, in particular, have captivated the most attention, offering the flexibility to modulate the chemical properties of phosphorus heterocycles through the integration of nitrogen (N) atom . They also exhibit critical utility in coordination chemistry, organic catalysis, photoelectric materials, and other areas.…”

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confidence: 99%

Hydrazone Phosphaketene as a Synthetic Platform To Obtain Three Classes of 1,2,4-Diazaphosphol Derivatives by Switchable Chemoselectivity Strategies

Wang,

Chen,

Wang

et al. 2024

Org. Lett.

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We introduce switchable chemoselectivity strategies based on the hydrazone phosphaketene intermediate to synthesize three classes of 1,2,4-diazaphosphol derivatives. First, the fivemembered heterocyclic P and O anion intermediates acted as nucleophilic agents in the selective construction of C−P and C−O bonds. Second, the phosphinidene served as a phosphorus synthon, allowing for the formation of C−P and C−N bonds. Finally, a stepwise mechanism, supported by DFT calculations, was invoked to explain the reaction selectivity.

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Azaphosphinines and their derivatives

Abstract: Azaphosphinines, six-membered heterocycles containing one phosphorus and one nitrogen atom, have emerged from the shadows of their single heteroatom-containing analogues. This review describes the synthesis and applications of these unique compounds.

Cited by 5 publications

References 133 publications

The n,π* States of Heteroaromatics: When are They the Lowest Excited States and in What Way Can They Be Aromatic or Antiaromatic?

The n,π* States of Heteroaromatics: When are They the Lowest Excited States and in What Way Can They Be Aromatic or Antiaromatic?

Accessing Five- and Seven-Membered Phosphorus-Based Heterocycles via Cycloaddition Reactions of Azophosphines

Hydrazone Phosphaketene as a Synthetic Platform To Obtain Three Classes of 1,2,4-Diazaphosphol Derivatives by Switchable Chemoselectivity Strategies

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