- OBERFLAECHEN-REAKTIONEN 15 Heterogene Dechlorierungen von Phosphorchloriden (X)PCl3 und R-PCl2 an , , x/TiO2> und sowie spektroskopische Evidenz fuer das Entstehen von Diphospha-dicyan PC-CP aus Cl2P-CC-PCl2
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Stimulated by the successful generation of unsaturated molecules with low-coordinated phosphorus centers by heterogeneous surface dechlorination, Cl2P-CC-PCl2 is synthesized and characterized by PE and mass spectra.In addition, curls, wool and catalysts x/TiO2> or are tested as potential dechlorinating agents for phosphorus halides like OPCl3, SPCl3, H3C-PCl2, H5C2-PCl2, (H3C)3C-PCl2 or H5C6-PCl2 in a gasflow reactor under reduced pressure and yield, inter alia, the following representative results: due to the thermodynamically favored formation of , or at the Mg surface, P4 is the only gaseous product identified from reactions of OPCl3 and SPCl3 with metal at higher temperatures.On the contrary, passing H3C-PCl2 at 600K over yields a reaction mixture containing P(CH3)3, (H3C)2P-P(CH3)2 (H3C-P)5 and CH4, which suggests an intermediate formation of surface phosphinidenes Mg>.Analogously, the pentamer (H3C-H2C-P)5 can be isolated from ethyldichlorophosphane.Reaction of the evaporated diphospha-cyanogen precursor Cl2P-C-PCl2 with the catalyst produces predominantly PCl3, and P4, but PE and mass spectra provide evidence that also minor amounts of the hitherto unknown molecule PC-CP are formed.
- Bock, H.,Bankmann, M.
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p. 167 - 191
(2007/10/02)
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- PRINCIPLES OF PHOSPHORUS CHEMISTRY
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An up-to-date concept of bonding in phosphorus compounds has to be based on the reality of molecular states.Molecules, which change their structure with energy, at present are best rationalized in terms of topology and symmetry, effective nuclear potentials and charge distribution.To reduce the complexity of the resulting manifold, comparison of equivalent states of chemical calculations, is strongly recommended.Adding the time-scale, molecular dynamics within the numerous degrees of freedom become important, also as a basis to gain some understanding og the rather complex microscopic reaction pathways of medium-sized molecules.Examples are presented to illustrate the use of spectroscopic "fingerprints" for the analysis and optimization of gasphase reactions as well as the benefit of inherent information on molecular states for the preparative phosphorus chemist.The catalytic dehydrochlorination of alkyldichlorophosphanes RH2C-PCl2 -> RHC=PCl -> R-CP and their dechlorination on magnesium metal surface are discussed in some detail as well as the generation of other unsaturated phosphorus molecules like Cl-P=O, Cl-P=S, ClP(=O)2, Cl-P(=S)2 or H3C-P=CH2.Approximate energy hypersurface calculations for the gasphase equilibrium P4 = 2P2 or for the unexpected dehydration (H3C)2HP=O -> H2O + H3C-P=CH2, which includes chemical activation, provide some insight into microscopic reaction pathways of phosphorus compounds.
- Bock, Hans
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- Evidence for Surface Phosphinidene Intermediates Mg> in the Heterogeneous Dechlorination of Alkyldichlorophosphanes RPCl2 by Mg Metal
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The heterogeneous dechlorination of alkyldichlorophosphanes by Mg metal at 600 K yields chemisorbed products which include penta-alkylcyclopentaphosphanes (RP)5, in addition to RnPH(3-n), R2P-PR2, P4, RH, and R-R, and thus provides evidence for surface phosphinidene intermediates Mg>.
- Bock, Hans,Bankmann, Martin
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p. 1130 - 1132
(2007/10/02)
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