Ab initio predictions of the lowest electronic states, structures vibrational frequencies of phenylphosphinidene

Hamilton, Tracy P.; Willis, A.; Williams, Stephanie D

doi:10.1016/0009-2614(95)01124-r

Cited by 16 publications

(17 citation statements)

References 24 publications

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“…The free 2,3-benzo-7-phosphanorbornadiene thus formed immediately collapses, but the resulting phenylphosphinidene does not react with tolan to give the expected phosphirene but, instead, abstracts hydrogen from toluene to give phenylphosphine, which is identified by its characteristic triplet: δ 31 P(PhPH 2 ) −123 ( 1 J H - P = 200 Hz). This result is coherent with the triplet ground state of phenylphosphinidene, but comes in sharp contrast with the reactivity of mesitylphosphinidene as formed by UV splitting of 1-mesitylphosphirane at low temperature . We suggest that the experiments of Gaspar initially produce the mesitylphosphinidene as a singlet excited state, which reacts, for example, with 2,3-dimethylbutadiene to give the corresponding 2-vinylphosphirane (and not the phospholene as expected for a triplet).…”

Section: Resultssupporting

confidence: 55%

2,3-Benzo-7-phosphanorbornadiene Complexes: Synthesis and Chemistry

2005

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The reaction of benzyne with 3,4-dimethylphosphole pentacarbonylmolybdenum complexes affords the corresponding 2,3-benzo-7-phosphanorbornadiene complexes through [4+2] cycloaddition. The condensation takes place on the less hindered side of the phosphole ring corresponding to the phosphorus substituent as shown by the X-ray crystal structure analysis of the phenyl derivative (2). The strain at the bridge of 2 (C−P−C angle ca. 80°) induces a variety of splitting reactions. Upon decomplexation by dppe at 110 °C in toluene, phenylphosphinidene is generated and recovered as phenylphosphine. Upon sulfurization under the same conditions, [PhPS2] is formed and trapped as a [4+2] adduct with 2,3-dimethylbutadiene. Potassium tert-butylate attacks the bridge in THF at −78 °C and, after methylation and hydrolytic workup, yields [Ph(Me)P(OH)Mo(CO)5].

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Section: Resultssupporting

confidence: 55%

2,3-Benzo-7-phosphanorbornadiene Complexes: Synthesis and Chemistry

2005

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“…The phenylphosphinidene, PC 6 H 5 , has been the subject of two recent theoretical studies, , which pointed toward a triplet ground state ( 3 A 2 ) and a 3 A 2 − 1 A 1 energy gap of −22 ± 3 kcal/mol. The calculated molecular properties of PC 6 H 5 are comparable to those of PCH 3 .…”

Section: Resultsmentioning

confidence: 99%

“…We have also found that, similar to the PCH 3 case, the triplet PC 2 H 5 is a stable species lying in deep potential wells. The phenylphosphinidene, PC 6 H 5 , has been the subject of two recent theoretical studies, 37,40 which pointed toward a triplet ground state ( 3 A 2 ) and a 3 A 2 -1 A 1 energy gap of -22 ( 3 kcal/mol. The calculated molecular properties of PC 6 H 5 are comparable to those of PCH 3 .…”

Section: Substituents Without Lonementioning

confidence: 99%

In Search of Singlet Phosphinidenes

1996

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We have examined singlet-triplet energy separations in different phosphinidenes (RP) substituted by first- and second-row elements, making use of ab initio molecular orbital theory. Our main purpose is to find out the substituents that particularly favor the singlet electronic state. The QCISD(T)/6-311++G(3df,2p) + ZPE level has been applied to small molecules and the CISD(Q) and QCISD(T) with the 6-311G(d,p) basis set for all species considered. We have identified few factors that come into play rendering the singlet phosphinidene more stable than the triplet. The parent phosphinidene, PH, has a triplet ground state lying 28 kcal/mol below the closed-shell singlet excited state. The triplet ground state is mainly favored when negative hyperconjugation is involved. In the boryl-, alkyl-, and silyl-substituted phosphinidenes, the triplet state remains by far the ground state. When the substituents have pi-type lone pair electrons (i.e., -NX(2), -PX(2), -OX, -SX), the singlet state becomes stabilized by such an amount that both states have similar energies or even a change in ground state occurs. The most stabilized singlet ground states are attributed to PSF and PSCl. P and S have similar p-orbital sizes, making pi-delocalization easier. Implantation of alkyl and/or amino groups in the beta-position of amino- and phosphinophosphinidenes also contributes to a singlet stabilization. Bulky beta-groups also destabilize the triplet state by a steric effect. From a practical viewpoint, amino (P-NR(2)) and phosphino (P-PR(2)) derivatives bearing large alkyl groups (R) are the most plausible and feasible targets for preparing phosphinidenes possessing a closed-shell singlet ground state.

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“…In contrast to its singly substituted analogue, p -phenylbisphosphinidene (C 6 H 4 P 2 ), the heavier congener of p -phenylbisnitrene, has so far neither been experimentally nor theoretically investigated. Ab initio studies of phenylphosphinidene , found a triplet ground state with a ca. 22 kcal/mol higher lying closed-shell singlet state and an open-shell singlet state nearby.…”

Section: Introductionmentioning

confidence: 99%

p-Phenylbisphosphinidene and Its Carbene and Nitrene Analogues: An ab Initio Study

et al. 2000

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Density functional and complete active space (CAS) SCF and CASPT2 calculations have been performed to investigate structural and electronic features of p-phenylbisphosphinidene and the analogous p-phenylbisnitrene, p-phenylbismethylene, p-phenylbis(fluoromethylene), and p-phenylbis(chloromethylene) molecules. Similar to the other species investigated, with the exception of p-phenylbis(fluoromethylene), p-phenylbisphosphinidene exhibits an open-shell singlet diradical ground state with a quinone-like structure. The singlet−triplet energy gap, computed with CASPT2 on CASSCF(10,10)/6-31+G* optimized structures, amounts to 1.78 kcal/mol. At the DFT (B3LYP/6-31+G*) level a value of 5.14 kcal/mol is obtained. Due to the highly multiconfigurational character of the p-phenylbisphosphinidene singlet and triplet wave functions, the DFT treatment becomes less accurate. Going to p-phenylbisnitrene, p-phenylbis(chloromethylene), p-phenylbis(fluoromethylene), and p-phenylbismethylene energies are better described by DFT calculations as the triplet wave functions have only one and the singlet wave functions exactly two leading configurations. The calculated singlet−triplet energy gaps are found to lie in a range of 1.3−2.2 kcal/mol at both DFT and CASPT2 levels of theory. p-Phenylbis(fluoromethylene) is a special case in the series as it has a closed-shell singlet ground state. The multiconfigurational treatment shows, however, that the singlet diradical state is very close in energy to the closed-shell singlet, even though the stability of the diradical is somewhat overemphasized by this method. The relative energies and the respective IR spectra are also discussed.

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Ab initio predictions of the lowest electronic states, structures vibrational frequencies of phenylphosphinidene

Cited by 16 publications

References 24 publications

2,3-Benzo-7-phosphanorbornadiene Complexes: Synthesis and Chemistry

2,3-Benzo-7-phosphanorbornadiene Complexes: Synthesis and Chemistry

In Search of Singlet Phosphinidenes

p-Phenylbisphosphinidene and Its Carbene and Nitrene Analogues: An ab Initio Study

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