Bis(2,4,6-tri-t-butylphenyl)bicyclotetraphosphan

Bis(2,4,6-tri-t-butylphenyl) bicyclotetraphosphane The reaction of white phosphorus with 2,4,6-tri-t-butylphenyllithium and 1-bromo-2,4,6-tri-t-butylbenzene yields bis (2, 4, 6-tri-t-butylphenyl) bicyclotetraphosphane 1 and bis (2, 4, 6-tri-t-butylphenyl) diphosphene 2. 1 is characterized by its nmr and mass spectra. The crystal and molecular structure are described.     

Relative initial populations of low-lying levels of hydrogenlike lithium after foil-excitation

Decay curves of the Lyman alpha and beta and Balmer alpha transitions in foil-excited Li⁺⁺ ions have been recorded for incident ion energies 0.1 to 1.3 MeV/amu. The curves have been analyzed with the aim of learning about the relative level populations ofn=2, 3 and 4 levels after ion-foil interaction. The results at the optimum beam energy for the production of the hydrogen-like ion tie in with an earlier isoelectronic study which showed aZ dependence of the population parameters. The data obtained for the range of velocities studied here may in addition be interpreted as to give evidence of a velocity effect of the population mechanism.     

Experimental transition probability for theE1 intercombination transition in Be-like Xe50+

The 2s^{2 1}S₀ — 2s2p³P°₁ intercombination transition in Be-like Xe⁵⁰⁺ has been observed and the intensity decay with time has been measured using a foil-excited fast ion beam. The transition wavelength value is found to be λ = (9.81±0.05) nm and the upper level lifetime to be τ = (0.47±0.05) ns. Both values agree with recent theoretical predictions.     

In situ-Erzeugung von [PX] und Insertion in (tBuP)3, (X = Cl,Br) Synthese der funktionalisierten Cyclophosphane (tBuP)3PX, [-(tBu)(X)P-2,3,4-(tBu)3]P4und Strukturbestimmung von (tBuP)3PCl

In situ Generation of [PX] and Insertion into (^tBuP)₃, (X = Cl, Br). Synthesis of the Functionalized Cyclophosphanes (^tBuP)₃PX, [1-(^tBu)(X)P-2,3,4-(^tBu)₃]P₄ and Structure Analysis of (^tBuP)₃PCl The redox system PX₃/SnX₂ (X = Cl, Br) can be used as a source for the in situ generation of halogenphosphanediyl [PX]. In the presence of tri-t-butylcyclotriphosphane (^tBuP)₃ the intermediately formed [PX] is added to a ring P atom followed by an insertion reaction, which leads to a ring expansion, whereby monohalogenocyclotetraphosphanes (^tBuP)₃PX (X = Cl, Br; 1, 2 ) are formed. Excess [PX] does not lead to further ring expansion but through a complex reaction course to the functionalized cyclotetraphosphanes [1-(^tBu)(X)P-2,3,4-(^tBu)₃]P₄, 3 (X = Br); 7 (X = Cl). 1, 2 and 3 could be obtained in a pure form and NMR and mass spectroscopically, 7 ³¹P-NMR spectroscopically, characterized. For 1 and 7 ³¹P? ^35,37Cl-isotopic shifts could be identified. 1 was further characterized by an X-ray structure analysis.     

Beam-foil lifetime study of then=3 complex in al-like Ti9+

The beam-foil spectrum obtained using a beam of Ti³⁺ ions of energy 10 MeV has been studied over the wavelength range from 14 nm to 80 nm. New assignments are suggested for 18 levels belonging to the levels of the 3p ³, 3s 3p 3d and 3s ² 4p configurations. The lifetimes of these levels, as determined from conventional multi-exponential curve fitting of their intensity decay curves, are typically about 30% longer than is forecast by theory. The same decay curves have also been used to represent the effect of cascade repopulation on the decay curves obtained for the resonance doublet levels of the 3s 3p ² and 3s ² 3d configurations. A discussion is given of the possible techniques for cascade correction in beam-foil lifetime measurements, and of the inclusion of a window function to represent the vignetting effect close to the foil. Lifetimes obtained using these techniques for the 3s ² 3d levels (38±6 ps for J=3/2, 36±5 ps for J=5/2), and the 3s3p ^{2 2} S level (99±6 ps),² P levels (60±15 ps for J=1/2, 50±15 ps for J=3/2) and² D levels (820±30 ps for j=3/2, 870±40 ps for J=5/2) are in good agreement with theoretical predictions.     

Alkylidinphosphane und -arsane. II. Über die Oxydation des Lithoxy-methylidinphosphans PC?O?Li mit Schwefeldioxid und Iod

Alkylidynephosphanes and -arsanes. II. Oxydation of Lithoxy-methylidynephosphane P?C? O? Li with Sulphur Dioxide and Iodine At ?50°C bis(1,2-dimethoxyethane-O,O′)lithoxymethylidynephosphane P?C? O? Li(dme)₂^1,2) ( 1 a ) [2] reacts almost quantitatively with sulphur dioxide or iodine in 1,2-dimethoxyethane solution to give bis(1,2-dimethoxyethane-O,O′)bis(tetrahydrofuran-O)(μ-1,2,4-triphospholo[1,2-a]-1,2,4-triphosphol-1,3,5,7-tetraonato(2?)-O¹,O⁷:O³,O⁵)dilithium ( 2 a ) and lithium dithionite or iodide respectively. From the reaction with sulphur dioxide the crystalline, pale yellow compound is obtained in 40% yield. The formation of the unusual anionic heterocycle, built up of four PCO units, may be explained by an oxydation of two [P?C? O]^? species first, followed by a nucleophilic attack of two other [P?C? O]^? anions and coupled ?intramolecular”? cycloaddition reactions. In the ³¹P{¹H} nmr spectrum two phosphorus atoms each of coordination number two and three give rise to two triplets with chemical shift values of 81.4 and 36.9 ppm and a ²J(PP) coupling constant of 31.7 Hz; the ¹³C{¹H} resonances of the [(PCO)₄]^2? anion come from an ABMM′X spin system, the X part being discussed in detail. An X-ray structure determination {Cmcm; a = 1 277.14(11); b = 1 487.7(2); c = 1 556.94(11) pm at ?100 ± 3°C; Z = 4 molecules; R₁ = 0.061; wR₂ = 0.150} shows compound 2 a to crystallize as a neutral complex of symmetry mm2. The anionic part of the molecule consists of two anellated 1,2-dihydro-5-oxo-1,2,4-triphosphol-3-olate rings which share the central P? P unit (P1? P1′ 215.3; P1–C1 189.1; C1 P2 178.4; C1 O1 123.9pm; C1? P1? P1′ 98.4; Cl? P1? C1″ 91.2; C1 P2 C1′ 98.7°). Thus compound 2a may be assigned to the group of P? P heterocycles with a butterfly structure [71–75] as well as to the well-known diacylphosphanides taking into account, however, the unusual E,E configuration of both O?C? P?C? O^? units. The lithium cations are square pyramidally coordinate (Li? O 193.5 to 209.1 pm), each additionally binding an 1,2-dimethoxyethane and a tetrahydrofuran molecule.     

Beam-foil lifetime study of Al-like titanium,iron and nickel

The lifetimes of the resonance levels in the Al-like ions Ti X, Fe XIV and Ni XVI have been obtained from beam-foil measurements using a variety of analytical techniques. The spectral analysis and identification of cascade transitions necessary for application of the ANDC procedure have been aided by recent observations of laser-produced plasmas. The lifetime values obtained from ANDC analyses for the 3s 3p ² doublet levels agree well with predictions based on semi-empirical Hartree-Fock calculations. However, the ANDC results for the 3s ² 3d levels fall between the values obtained using multi-exponential curve-fitting and from the calculations.     

CPS 758 Untersuchung des Mischungsgleichgewichts binärer Polymermischungen

The phase diagram of a binary polymer blend can be derived from the glass temperaturesT _g of the demixed phases under the following conditions:

1. The T_g's of the pure components are sufficiently different from one another.
2. TheT _g 's of the one-phase homogeneous mixtures can be determined and vary monotonically with composition.
3. The equilibrium state of the mixture is attained after sufficient long annealing at temperatureT.
4. The equilibrium state at the temperatureT can be frozen by quenching.

These conditions are examined for mixtures of polystyrene (PS) and tetra methyl-bis-phenol A-polycarbonate (TMPC). The phase separation kinetics is investigated with respect to size and composition of the co-existing phases. The co-existance curves (binodal with lower critical point) are determined for mixtures with various molar masses of the PS component. The problems concerning the cloud point curves are shortly discussed. BetweenT _g and the binodal the one-phase mixtures exist in a hindered thermodynamic state, because the crystallization of the TMPC component is a very slow process which requires very long annealing. With increasing amounts of PS in the mixture the crystallization half time of TMPC is lowered.     

Reaktionen des 1,1′, 3,3′-Tetrakis(dimethylamino)-1λ5, 3λ5-diphosphets mit S?H-aciden Verbindungen

Reaction of 1,′, 3,3′-Tetrakis(dimethylamino)-1λ⁵,3λ⁵-diphosphete with S? H Acidic Compounds. Reaction of 1,′,3,3′-tetrakis(dimethyl-amino)-1λ⁵,3λ⁵-diphosphete ( 1 ) with hydrogen sulfide yields bis(dimethylamino)thiophosphonylmethylidene-methyl-bis(dimethylamino)phosphorane ( 5 ).Water eliminates dimethylamine from 5 and forms bis(dimethyl-amino)thiophosphonyl-methyl(dimethylamino)phosphonylmethylene 6 . The reaction of 1 with ethylmercaptane yields the 2,4-bis(ethylthio)-derivative of 1 , i.e. compound 8 and bis(dimethylamino)phosphanylmethylidene-methyl-bis(dimethylamino)phosphorane ( 9 ), which is also formed from 1 and 2,4,6-trimethylphenylphosphane. Thiophenol protonates 1 to give the corresponding cation which is isolated as its thiophenolate, 10 . Properties, nmr and mass spectra of 5, 6 and 8 – 10 are described and discussed.     

1,2-Diphospha-3,4-diboretane und 1,3-Diphospha-2,4,5-triborolan: Synthese und Struktur sowie Berechnungen zur Molekülstruktur Über den Einfluß von Substituenten auf die Struktur von 1,2-Diphospha-3,4-diboretan

1,2-Diphospha-3,4-diboretanes and 1,3-Diphospha-2,4,5-triborolane: Synthesis and Structure as well as Calculations on the Molecular Structure On the Effect of Substituents on the Structure of 1,2-Diphospha-3,4-diboretane [2 + 2]-Cyclocondensation reactions led to the synthesis of the 1,2-diphospha-3,4-diboretanes [(t-BuP)₂B₂(NMe₂)₂], 1 a , and [(t-BuP)₂B(NMe₂)B(NiPr₂)], 1 b . Their molecular structures have been determined by X-ray methods, and these are compared with the structure of [(t-Bu)P? BN(iPr₂)]₂, 2 a . Compounds 1 show a folded B₂P₂ four membered ring having tert.-butyl groups in anti-positions. Ab initio calculations on 1,2-diphospha-3,4-diboretanes demonstrate that two conformers with anti-orientation of the substituents at the phosphorus atoms can be expected. These differ by the relative orientation of the almost planar P₂BR groups to the BP₂ plane. The influence of substituents (H and NH₂ at the B atoms, and H and Me at the P atoms) on the ring conformation has been studied. Finally, the first derivative of a 1,3-diphospha-2,4,5-triborolane, 3 a , is reported.