A Promising Method for Phosphinidene Generation: Complexes of Phosphinidenes with N‐Donor ligands

Benkő, Zoltán; Gudat, Dietrich; Nyulászi, László

doi:10.1002/chem.200701077

Cited by 16 publications

(16 citation statements)

References 57 publications

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“…Computations were performed at the DFT B3LYP/6-311G** level of theory, which is known to perform well for main group systems. [ 7k , 23 ] As a first step, we decided to investigate the energy difference between the s- cis and s- trans conformations of PPAs 5 c and 6 c with respect to the torsion angle between the phosphole and the phosphaalkene moiety (Figure 4 ). Since both conformations were observed in solid-state structures of 5 and 6 , the expectation was that the energy difference between the two arrangements of the phosphorus heteroatoms would be very small.…”

Section: Resultsmentioning

confidence: 99%

Phosphorus Centers of Different Hybridization in Phosphaalkene‐Substituted Phospholes

Öberg

Orthaber

Lescop

et al. 2014

Chemistry A European J

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Phosphole-substituted phosphaalkenes (PPAs) of the general formula Mes*P=C(CH3)–(C4H2P(Ph))–R 5 a–c (Mes*=2,4,6-tBu3Ph; R=2-pyridyl (a), 2-thienyl (b), phenyl (c)) have been prepared from octa-1,7-diyne-substituted phosphaalkenes by utilizing the Fagan–Nugent route. The presence of two differently hybridized phosphorus centers (σ2,λ3 and σ3,λ3) in 5 offers the possibility to selectively tune the HOMO–LUMO gap of the compounds by utilizing the different reactivity of the two phosphorus heteroatoms. Oxidation of 5 a–c by sulfur proceeds exclusively at the σ3,λ3-phosphorus atom, thus giving rise to the corresponding thioxophospholes 6 a–c. Similarly, 5 a is selectively coordinated by AuCl at the σ3,λ3-phosphorus atom. Subsequent second AuCl coordination at the σ2,λ3-phosphorus heteroatom results in a dimetallic species that is characterized by a gold–gold interaction that provokes a change in π conjugation. Spectroscopic, electrochemical, and theoretical investigations show that the phosphaalkene and the phosphole both have a sizable impact on the electronic properties of the compounds. The presence of the phosphaalkene unit induces a decrease of the HOMO–LUMO gap relative to reference phosphole-containing π systems that lack a P=C substituent.

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Section: Resultsmentioning

confidence: 99%

Phosphorus Centers of Different Hybridization in Phosphaalkene‐Substituted Phospholes

Öberg

Orthaber

Lescop

et al. 2014

Chemistry A European J

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“…Computational studies indicated that this reaction, although being highly endothermic for molecules with isolated rings, becomes energetically more favorable for annulated heterocycles whose fragmentation products may gain additional stabilization energy from rearomatization of the remaining ring fragment, and is under these conditions predicted to provide a viable approach for the generation of free phosphinidenes [69] . Finally, a preliminary computational study on the dimerization of 1,3,2-diazaphospholenyl radicals suggested that the easy formation of these species might be facilitated by a very low dissociation energy of the corresponding dimer [46] .…”

Section: Chemical Reactivity Aspects and Frontier Orbital Considerationsmentioning

confidence: 98%

“…3.1.2 or are serendipitous results that have only briefly been mentioned in the context of a more extensive investigation [18] , and will not be explicitly repeated here. The [4 + 1]-retro-addition reactions of annulated NHP derivatives generating a -diimines and transient phosphinidenes (Scheme 8 ) have been theoretically predicted [69] but are still awaiting experimental verification. An interesting case of a [4 + 2]-cycloadditioncycloreversion sequence leading to ring transformation was reported for the reaction of 1,3,2-diazaphospholes with alkynes to give 1,2-azaphospholes and nitriles [70] .…”

Section: Chemical Reactivitymentioning

confidence: 98%

Recent Developments in the Chemistry of N-Heterocyclic Phosphines

Gudat

2009

Topics in Heterocyclic Chemistry

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This chapter gives a survey on five-and six-membered phosphorusnitrogen heterocyclic compounds whose rings combine a phosphazene (>N-P = N-) or phosphazane (>N-P(X)-N<) unit with an unsaturated C 2 or C 3 building block. Representatives contain structurally diverse species like aromatic 1,3,2-diazaphosphinines and (benzo)-1,3,2-diazaphospholes, cationic counterparts of subvalent main-group carbene analogues like 1,3,2-diazaphospholenium ions and phosphenium-diketiminates, and neutral heterocycles like 1,3,2-diazaphospholenes featuring unusual structures and reactivities. The exploration of these species developed rapidly in the last two decades in the wake of cutting edge research on multiple bonding and low coordination in the chemistry of heavier main-group elements, and the discovery of stable carbenes. This review summarizes the elaboration of synthetic approaches for different types of N -heterocyclic phosphine derivatives, discusses their characterization by physical and computational methods which furnished a thorough understanding of structure and bonding, and finally highlights accomplishments in the exploration of the chemical properties at the border of classical organic heterocyclic chemistry and molecular inorganic chemistry.

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“…Since the DAP framework is on the other hand predestined for electrocyclic reactions, 11,36,37,66 there should be ample room for ring transformation processes. Following theoretical predictions 66 and mass spectrometric evidence 11 of controlled cycloreversion reactions of DAPs, recently the first direct observations of such processes have been reported (Scheme 16). Thus, the bis-Scheme 14 (a) Reduction of Cl-DAPs to H-DAPs using Mg/Et 3 NHCl via disproportionation of diazaphospholonyl radicals as the key step (R = Dipp, 2-tBuC 6 H 4 ); 15 (b) photocatalytic reductive generation of H 2 (R = Dipp).…”

Section: To New Frontiersring Opening Reactionsmentioning

confidence: 99%

A very peculiar family of N-heterocyclic phosphines: unusual structures and the unique reactivity of 1,3,2-diazaphospholenes

Gudat

2016

Dalton Trans.

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This Perspective gives an account of the peculiar electronic and molecular structures of N-heterocyclic phosphines featuring either a single 1,3,2-diazaphospholene (DAP) ring with an exocyclic P-substituent X or two DAP rings linked by a P-P bond (bis-diazaphospholenyls), respectively, and their impact on the chemical properties of these molecules. The bonding situation in simple DAPs is epitomized by strong hyperconjugation between endocyclic π-type electrons and the exocyclic P-X bond. This interaction may induce a perceptible ionic polarization of the P-X bond which can persist even in the limit of a vanishing electronegativity gradient between P and X, and becomes visible in unusual geometric distortions of molecular structures and a unique chemical behaviour. Structural distortions are particularly evident in bond lengthening effects in P-halogen and P-phosphino derivatives R2P-DAP (with R2P ≠ DAP) which span the whole range from covalent molecules to contact ion pairs with a close relation to frustrated Lewis-pairs. The most significant impact on the chemical properties is found for P-phosphino- and P-hydrogen derivatives where reactions at substantially accelerated rates or totally new reaction modes can be observed, and new stoichiometric and first catalytic processes exploiting these features are currently emerging. The recently discovered bis-diazaphospholenyls differ from the simple derivatives as their central bond remains unpolarised as a consequence of the symmetric molecular structure. The occurrence of low-energy P-P bond homolysis that was nonetheless observed in one case is according to the results of thermochemical studies of P-P bond fission reactions attributable to the effects of steric congestion and induces chemical reactivity that can be considered complementary to that of the simple R2P-DAPs. Some concluding remarks will pay attention to a facet of DAP reactivity that has so far been widely neglected but is currently receiving increasing attention, namely well-defined ring-opening processes.

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A Promising Method for Phosphinidene Generation: Complexes of Phosphinidenes with N‐Donor ligands

Cited by 16 publications

References 57 publications

Phosphorus Centers of Different Hybridization in Phosphaalkene‐Substituted Phospholes

Phosphorus Centers of Different Hybridization in Phosphaalkene‐Substituted Phospholes

Recent Developments in the Chemistry of N-Heterocyclic Phosphines

A very peculiar family of N-heterocyclic phosphines: unusual structures and the unique reactivity of 1,3,2-diazaphospholenes

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