Showing papers on "Pi interaction published in 1975"
106 citations
TL;DR: In this article, the trans influence of the ligand on the performance of a series of olefin-platinum(II) π complexes was investigated by measuring pmr, cmr, vibrational spectra and by extended Huckel MO calculations for a series π complex, trans-[Pt(C 2 H 4 )LCl 2 ]
18 citations
TL;DR: The irradiation of methyl acetopyruvate in cyclopentadiene using a high pressure mercury lamp yielded two (4+2)π and two (2+2π)π adducts as mentioned in this paper.
Abstract: The irradiation of methyl acetopyruvate in cyclopentadiene using a high-pressure mercury lamp yielded two (4+2)π and two (2+2)π adducts These products were inert under the photochemical conditions
13 citations
TL;DR: In this article, it was shown that the ϱ meson appears narrower in measurements of the pion form factor, F π ( s ), than in ππ phase shift analyses of OPE reactions.
11 citations
TL;DR: In this paper, the ultraviolet absorption and phosphorescence emission spectra of various methyl and phenyl substituted 4-pyrones, 4-thiopyrones and 4-pyridones have been measured.
Abstract: The ultraviolet absorption and phosphorescence emission spectra of various methyl and phenyl substituted 4-pyrones, 4-thiopyrones and 4-pyridones have been measured. The lowest energy absorption of the unhindered 4-pyrones and 4-thiopyrones is the carbonyl n, π* transition, whereas 4-pyridones do not show the n, π* transition. The hypsochromic shifts and hypochromic effects observed for the hindered 4-pyrones, 4-thiopyrones and 4-pyridones are attributed to the steric effect of substituents. These compounds show little or no fluorescence at room temperature or at 77 K, while the lowest triplet states are mainly of π, π* orbital character. An intramolecular heavy-atom effect appears to play an important role in the phosphorescence spectra of 4-thiopyrones. The results of SCF LCAO MO calculations with configuration interaction are reported for each of these three classes of compounds.
11 citations
TL;DR: The ability of transition metal atoms and clusters to catalyze olefin isomerization was traced to metal d orbital stabilization of the OO transition state π orbital.
10 citations
01 Oct 1975
TL;DR: In this article, the spectra of tetrachloroethylene, monofluoroethylene and trifluoromethane were studied in the region 150-250 nm in the gas, solid and Kr matrix.
Abstract: The spectra of tetrachloroethylene, monofluoroethylene, gem-, cis- and trans-difluoroethylene and trifluoroethylene were studied in the region 150–250 nm in the gas, solid and Kr matrix. The valence character of the π a π* transition in the various compounds was verified and the Rydberg transitions were identified. The lowest energy band in the fluoroethylene was found to be a Rydberg transition. The vibronic structure of the π a π* transition in tetrachloroethylene indicates that the excited state geometry is planar. The existence of a π a σ* transition at lower energy than the π a π* transition was verified for cis-difluoroethylene and trifluoroethylene.
10 citations
7 citations
TL;DR: In this article, the dependence of the in-phase, out-of-plane CH bending on π electron density in aromatics made by Kross was applied to pyridine molecular complexes.
7 citations
TL;DR: In this paper, the photochemical addition reaction of cycloheptatriene with p-benzoquinone and 1,4-naphthoquinone yielded the spiro-ethers having 7-oxa-bicyclo[4,2,1] nonadiene moiety by the characteristic (6+2)π addition process.
Abstract: The photochemical addition reaction of cycloheptatriene with p-benzoquinone and 1,4-naphthoquinone yielded the spiro-ethers having 7-oxa-bicyclo[4,2,1] nonadiene moiety by the characteristic (6+2)π addition process. The latter quinone further produced the carbocyclic (2+2)π - and (6+2)π cycloadducts. Either (4+2)π adducts or dioxetanes were undetectable in both cases. The photoadducts were stable under their formation conditions, showing no tendency to cause the isomerization.
TL;DR: In this article, the budding pomeron is produced in meson-meson scattering and the first inelastic channels to couple strongly to π + π+ are investigated.
TL;DR: The results of a stereochemical study of the intramolecular triplet energy transfer between indanone (donor) and naphthalene (acceptor) groups are discussed in this article.
Abstract: The results of a stereochemical study of the intramolecular triplet energy transfer between indanone (donor) and naphthalene (acceptor) groups are discussed. Two diastereoisomeric spatial arrangements were chosen in which the donor occupies the endo and exo configuration, respectively, on conformationally rigid bicyclic frames 1,8- and 2,3-annelated to naphthalene. In the endo geometry a transfer route via a triplet donor-acceptor exciplex specific to through-space interaction between the two π systems (providing for additional radiationless T S deactivation) is proposed to compete with an efficient through-α-bond exchange transfer mechanism operative in both the endo and exo arrangements. In connection with this study the dual phosphorescence phenomenon of 1-indanone was reinvestigated. It was found that the favored intersystem crossing routes are S1 (n, π*) T(n, π*) and S2,3 (π,π*n) T(π,π*) and that internal conversion to S1 competes efficiently with S(π,π*) T(π,π*) intersystem crossing only from higher vibrational levels of the S2 and S3 states.