It has been demonstrated that in the presence of catalytic amounts of certain metal ions or metal complexes, various strained derivatives of cyclobutene can undergo an extremely facile disrotatory ring opening to yield derivatives of butadiene. An explanation for the “apparent” break-down of the Woodward-Hoffman rules is offered in terms of the formation of intermediate organometallic pi complexes and consideration of the subsequent energetics involved for the ring opening reaction of these complexes.
{"title":"Extension of the Woodward-Hoffman rules to organometallic systems","authors":"R. Pettit, H. Sugahara, J. Wristers, W. Merk","doi":"10.1039/DF9694700071","DOIUrl":"https://doi.org/10.1039/DF9694700071","url":null,"abstract":"It has been demonstrated that in the presence of catalytic amounts of certain metal ions or metal complexes, various strained derivatives of cyclobutene can undergo an extremely facile disrotatory ring opening to yield derivatives of butadiene. An explanation for the “apparent” break-down of the Woodward-Hoffman rules is offered in terms of the formation of intermediate organometallic pi complexes and consideration of the subsequent energetics involved for the ring opening reaction of these complexes.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"53 1","pages":"71-78"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79237566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
New rotational Raman spectra have been obtained in solid ortho-hydrogen and para-deuterium. In the orientationally ordered state a total of five librational lines was observed in the region 5 → 30 cm–1 which is consistent with a previous proposal that the generally accepted Pa3 structure be replaced by a rhombohedral distortion of Pa3, namely, text-decoration:overlineR3. However, the J= 0 → 2 spectra of para-hydrogen and ortho-deuterium impurities have four lines, three of which seem to fit the Pa3 structure. We conclude that a consistent picture of the ordered state has to include additional interactions such as a libron-phonon coupling.
{"title":"Rotational excitations in solid hydrogen and deuterium in the ordered state","authors":"I. Silvera, W. Hardy, J. McTague","doi":"10.1039/DF9694800054","DOIUrl":"https://doi.org/10.1039/DF9694800054","url":null,"abstract":"New rotational Raman spectra have been obtained in solid ortho-hydrogen and para-deuterium. In the orientationally ordered state a total of five librational lines was observed in the region 5 → 30 cm–1 which is consistent with a previous proposal that the generally accepted Pa3 structure be replaced by a rhombohedral distortion of Pa3, namely, text-decoration:overlineR3. However, the J= 0 → 2 spectra of para-hydrogen and ortho-deuterium impurities have four lines, three of which seem to fit the Pa3 structure. We conclude that a consistent picture of the ordered state has to include additional interactions such as a libron-phonon coupling.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"5 1","pages":"54-60"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82496380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Measurements of the total intensity, the horizontally and vertically polarized components, and the Brillouin spectrum of light scattered from two molecular crystals, trimethylacetic acid and succinonitrile, have been made over a range of temperature in the plastic phase of these materials up to and a little beyond the melting point. The spectral and intensity changes are correlated with the motions available to the molecules in the crystal.
{"title":"Studies of brillouin and rayleigh scattering in molecular crystals","authors":"A. J. Hyde, J. Kevorkian, J. Sherwood","doi":"10.1039/DF9694800019","DOIUrl":"https://doi.org/10.1039/DF9694800019","url":null,"abstract":"Measurements of the total intensity, the horizontally and vertically polarized components, and the Brillouin spectrum of light scattered from two molecular crystals, trimethylacetic acid and succinonitrile, have been made over a range of temperature in the plastic phase of these materials up to and a little beyond the melting point. The spectral and intensity changes are correlated with the motions available to the molecules in the crystal.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"78 1","pages":"19-25"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82844428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By inelastic scattering of slow neutrons from solid adamantane (C10H16) it is found that in the high-temperature phase (T > 208K) the quasi-elastic distribution contains two components, a δ-function and a Lorentzian. A comparison of the latter component to model calculations suggests that it originates from dynamical orientation defects, i.e., rotational jumps of the molecules between equilibrium orientations. The relaxation time of this motion and its temperature dependence are determined and compared to n.m.r. observations. The theoretical model also predicts a distinct dependence of the scattering on the momentum transfer. With the help of this dependence the motion can be identified in detail.
{"title":"Dynamics of orientational defects in solid adamantane","authors":"R. Stockmeyer","doi":"10.1039/DF9694800156","DOIUrl":"https://doi.org/10.1039/DF9694800156","url":null,"abstract":"By inelastic scattering of slow neutrons from solid adamantane (C10H16) it is found that in the high-temperature phase (T > 208K) the quasi-elastic distribution contains two components, a δ-function and a Lorentzian. A comparison of the latter component to model calculations suggests that it originates from dynamical orientation defects, i.e., rotational jumps of the molecules between equilibrium orientations. The relaxation time of this motion and its temperature dependence are determined and compared to n.m.r. observations. The theoretical model also predicts a distinct dependence of the scattering on the momentum transfer. With the help of this dependence the motion can be identified in detail.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"10 1","pages":"156-161"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74754782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. D. Duncan, J. C. Green, M. Green, K. Mclauchlan
The coupling constants JH–D of the CH2D group in the deuteriomethyl derivatives, π-C5H5Fe(CO)2CH2D, π-C5H5(Mo or W)(CO)3CH2D, Mn(CO)5CH2D, π-C5H5Ni(Ph3P)R (where R = CH2D, m- or p-C6H4CH2D), and XPt(Et3P)2CH2D (where X = Br, NO3, or SCN), have been determined. The sign of JH–D in the iron compound has been shown to be negative. The magnitudes of JH–H are discussed in terms of a π-donor effect from the metal to the neighbouring carbon.
{"title":"Evidence for a π-donor effect in transition metal-carbon bonds from H—D coupling constants","authors":"J. D. Duncan, J. C. Green, M. Green, K. Mclauchlan","doi":"10.1039/DF9694700178","DOIUrl":"https://doi.org/10.1039/DF9694700178","url":null,"abstract":"The coupling constants JH–D of the CH2D group in the deuteriomethyl derivatives, π-C5H5Fe(CO)2CH2D, π-C5H5(Mo or W)(CO)3CH2D, Mn(CO)5CH2D, π-C5H5Ni(Ph3P)R (where R = CH2D, m- or p-C6H4CH2D), and XPt(Et3P)2CH2D (where X = Br, NO3, or SCN), have been determined. The sign of JH–D in the iron compound has been shown to be negative. The magnitudes of JH–H are discussed in terms of a π-donor effect from the metal to the neighbouring carbon.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"28 1","pages":"178-182"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83377704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The procedure for fitting model calculations to measured phonon dispersion curves in molecular crystals is discussed. The simplest model involves the assumption that the molecules behave as rigid bodies. The results for perdeuterohexamethylenetetramine are then fitted to this model by the method of least-squares. The question of molecular distortion in external mode vibration is raised, and the results for a model calculation on perdeutero-naphthalene are given. These suggest that the distortion effect should not be ignored in model fitting procedures, as some modes are found to be shifted by as much as 8 cm–1. The calculations also yield large shifts in the internal mode frequencies and show the dispersion relation for these modes.
{"title":"Molecular crystal phonon dispersion curves and model fitting","authors":"G. Pawley","doi":"10.1039/DF9694800125","DOIUrl":"https://doi.org/10.1039/DF9694800125","url":null,"abstract":"The procedure for fitting model calculations to measured phonon dispersion curves in molecular crystals is discussed. The simplest model involves the assumption that the molecules behave as rigid bodies. The results for perdeuterohexamethylenetetramine are then fitted to this model by the method of least-squares. The question of molecular distortion in external mode vibration is raised, and the results for a model calculation on perdeutero-naphthalene are given. These suggest that the distortion effect should not be ignored in model fitting procedures, as some modes are found to be shifted by as much as 8 cm–1. The calculations also yield large shifts in the internal mode frequencies and show the dispersion relation for these modes.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"7 1","pages":"125-130"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82557632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mean square thermal displacements of the chlorine and deuterium atoms were derived both in the ordered orthorhombic and in the disordered cubic phase of deuterium chloride by a least-squares study of the neutron powder diffraction patterns recorded at four temperatures over the 4.2 to 111.5 K range. The atomic displacements were subsequently interpreted as due to the superposition of the internal stretching vibrations and of the rigid-body translational and angular vibrations of the molecules. The analysis of the results revealed substantial rigid-body vibrational components in the zero-point motion of the molecules and a rapid rise in the amplitude of the in-plane angular vibrations on approaching the transition point. It also showed a small but possibly significant lengthening of the CI—D bond as the temperature decreases. Finally, it gave a fuller understanding of the disordered cubic phase as a dynamic mixture of short-lived polymers of varying lengths and shapes.
{"title":"Neutron diffraction study of molecular motion in solid deuterium chloride","authors":"E. Sándor, R. Farrow","doi":"10.1039/DF9694800078","DOIUrl":"https://doi.org/10.1039/DF9694800078","url":null,"abstract":"Mean square thermal displacements of the chlorine and deuterium atoms were derived both in the ordered orthorhombic and in the disordered cubic phase of deuterium chloride by a least-squares study of the neutron powder diffraction patterns recorded at four temperatures over the 4.2 to 111.5 K range. The atomic displacements were subsequently interpreted as due to the superposition of the internal stretching vibrations and of the rigid-body translational and angular vibrations of the molecules. The analysis of the results revealed substantial rigid-body vibrational components in the zero-point motion of the molecules and a rapid rise in the amplitude of the in-plane angular vibrations on approaching the transition point. It also showed a small but possibly significant lengthening of the CI—D bond as the temperature decreases. Finally, it gave a fuller understanding of the disordered cubic phase as a dynamic mixture of short-lived polymers of varying lengths and shapes.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"11 1","pages":"78-86"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75798667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The structure of the molecules (CH3)3Si—CC—H, (CH3)3Si—CC—Cl and (CH3)3Ge—CC—Cl as gases have been determined using electron diffraction. The lengths of the CC bond show no significant differences from the corresponding bond length in carbon compounds. We conclude therefore that the length of the CC bond is insensitive to π-electron delocalization.
{"title":"Structure of molecules of type (CH3)3X—CC—Y (XSi, Ge, YH, Cl) determined by electron diffraction","authors":"W. Zeil, J. Haase, M. Dakkouri","doi":"10.1039/DF9694700149","DOIUrl":"https://doi.org/10.1039/DF9694700149","url":null,"abstract":"The structure of the molecules (CH3)3Si—CC—H, (CH3)3Si—CC—Cl and (CH3)3Ge—CC—Cl as gases have been determined using electron diffraction. The lengths of the CC bond show no significant differences from the corresponding bond length in carbon compounds. We conclude therefore that the length of the CC bond is insensitive to π-electron delocalization.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"14 1","pages":"149-156"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87645961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The physical and chemical properties, including electronic absorption, infra-red, and 1H n.m.r. spectra of cobalt(III) complexes of the type CoA4XY, where A4 can be corrin, a Schiffs base, or dimethylglyoxime and X a carbon ligand, are discussed in terms of the change in electron density in the complex. It is shown that alkyl ligands act as strong donors, often giving rise to five-co-ordinate complexes. The relationship of the properties of these five-co-ordinate cobalt(III) complexes to those of analogous cobalt(II) nickel(II) and palladium(II) complexes is discussed and the difference between the cobalt-carbon bond in the five- and six-co-ordinate complexes considered.
{"title":"Some properties of metal complexes containing one metal-carbon bond","authors":"H. Hill, J. M. Pratt, ROBERT J. P. Williams","doi":"10.1039/DF9694700165","DOIUrl":"https://doi.org/10.1039/DF9694700165","url":null,"abstract":"The physical and chemical properties, including electronic absorption, infra-red, and 1H n.m.r. spectra of cobalt(III) complexes of the type CoA4XY, where A4 can be corrin, a Schiffs base, or dimethylglyoxime and X a carbon ligand, are discussed in terms of the change in electron density in the complex. It is shown that alkyl ligands act as strong donors, often giving rise to five-co-ordinate complexes. The relationship of the properties of these five-co-ordinate cobalt(III) complexes to those of analogous cobalt(II) nickel(II) and palladium(II) complexes is discussed and the difference between the cobalt-carbon bond in the five- and six-co-ordinate complexes considered.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"28 1","pages":"165-171"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90264828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Infra-red spectra of compounds of the type {(CO)3. Fe[X. C6Y5]}2, (X = S, Se or Te; Y = H or F), have been studied in the carbonyl stretching region. Four bands were observed. The interactions between the carbonyl groups were assumed to take place via iron 3d orbitals. A model to describe the spectra was developed in which a three-fold axis was retained at each Fe(CO)3 group and between the two iron atoms. It was concluded that the carbonyl-carbonyl interaction route between the iron atoms was via direct 3d–3d overlap and not via the d or p orbitals of X. Interaction force constants were calculated and their variation with X and Y discussed. The model was extended to explain the spectra of related compounds.
{"title":"Interactions of carbonyl groups in compounds containing metal-metal bonds","authors":"M. Reddy, D. Urch","doi":"10.1039/DF9694700053","DOIUrl":"https://doi.org/10.1039/DF9694700053","url":null,"abstract":"Infra-red spectra of compounds of the type {(CO)3. Fe[X. C6Y5]}2, (X = S, Se or Te; Y = H or F), have been studied in the carbonyl stretching region. Four bands were observed. The interactions between the carbonyl groups were assumed to take place via iron 3d orbitals. A model to describe the spectra was developed in which a three-fold axis was retained at each Fe(CO)3 group and between the two iron atoms. It was concluded that the carbonyl-carbonyl interaction route between the iron atoms was via direct 3d–3d overlap and not via the d or p orbitals of X. Interaction force constants were calculated and their variation with X and Y discussed. The model was extended to explain the spectra of related compounds.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"27 1","pages":"53-58"},"PeriodicalIF":0.0,"publicationDate":"1969-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90310615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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