Fluorsulfonylstickstoffverbindungen

The reactions of fluorosulfonylurea derivatives with phosphorus pentachloride in carbon tetrachloride leads to and . These compounds are easily fluroinated by arsenic trifluoride to the corresponding fluorosulfonyl derivatives. It was shown that PCl₅ is reliable for the fluorine-chlorine exchange. Isocyanate esterchlorides as well as carbonyl-fluoride derivatives react with compounds which have an active hydrogen atom. By this way were prepared: . By hydrolysis of , is probably formed as the first reaction product. The acid could be trapped with tetraphenylphosphoniumchloride as a well-cristalline salt. Fluorosulfonyl isocyanate reacts with aldehydes to the following compounds: FSO₂N ? CHCH₃, FSO₂N ? CHC₂H₅, FSO₂N ? CH? CH(CH₃)₂ and FSO₂N ? CHC₆H₅. The physical and chemical properties as well as IR and NMR spectra of the compounds are described and, in part, compared and discussed.     

Amino-phosphane. X. Einige Additionsreaktionen von N-Diphenylphosphinotetraphenyldiphosphin-imid

Diphenylphosphorous chloride and methyl iodide add readily to the N-bonded P(III)-atom of (C₆H₅)₂P? P(C₆H₅)₃?N? P(C₆H₅)₂ forming the salts [(C₆H₅)₂P? P(C₆H₅)₂ N P(C₆H₅)₂? P(C₆H₅)₂]Cl and [(C₆H₅)₂P? P(C₆H₅)₂ N P(C₆H₅)₂. CH₃]I, respectively. A similar behaviour is observed with sulfur: Under mild conditions (C₆H₅)₂P? P(C₆H₅)₂?N? P(C₆H₅)₂ = S is formed but forcing conditions are required to produce S = P(C₆H₅)₂? P(C₆H₅)₂?N? P(C₆H₅)₂?S. The monosulfide is also obtained by treating (C₆H₅)₂P(S)N[Si(CH₃)₃]₂ with diphenylphosphorous chloride, indicating the favoured formation of the phosphazene system as compared with the phosphazane system Confirmation of the structures comes from ³¹P nmr and IR data, and for the sulfides also from their degradation with bromine.     

Versuche zur Darstellung von zweifach silyliertem Nitramid

Experiments for the Preparation of Doubly Silylated Nitroamine Silylated derivatives of nitroamines can be obtained by treating nitryl compounds with silazanes, i. e. via formation of an N? N bond: The reaction product can be isolated in the case of R ? CH₃, R′? Si(CH₃)₃, whereas [(CH₃)₃Si]₂ NNO₂ is unstable and cannot be obtained at room temperature. Isomeric Bis(trimethylsilyl)-hyponitrite formed by reaction of silver hyponitrite with trimethylchlorosilane is similarly unstable. Cleavage of siloxanes by nitryl and nitrosyl compounds is discussed in connection with the above reaction.     

Synthese und NMR-Spektren von λ5-Diphospheten Die Struktur des 2,4-Diphenyl-1,1,3,3-tetrakis(diethylamino)-1λ5,3λ5-diphosphets

Synthesis and NMR Spectra of λ⁵-Diphosphets. Structure of 2,4-Diphenyl-1,1,3,3-tetrakis (diethylamino)-1λ⁵, 3λ⁵-diphosphete Preparation, properties, and n.m.r. spectra of C₂H₅PF₂[N(C₂H₅)₂]₂, CH₂?PF[N(C₂H₅)₂]₂, and the diphosphetes {RC?P[N(C₂H₅)₂]₂}₂ (R) ? H ( 5a ), CH₃ [( 5b )] are described. The λ⁵-diphosphete {HC?P(NR₂)₂}₂ (R ? CH₃) reacts with BF₃ · O(C₂H₅)₂ to give which is transformed into by n-C₄H₉Li. The crystal and molecular structure of 2,4-diphenyl-1,3,3-tetrakis(diethylamino)-1λ⁵,3λ⁵-diphosphete 2 are reported and discussed.     

Zur Darstellung von Cyclophosphaten,Cyclophosphatophosphonaten, Diphosphonaten und Diphosphiten in Harnstoffschmelzen

Preparation of Cyclophosphates, Cyclophosphatophosphonates, Diphosphonates, and Di-phosphites in Urea Melts Ammonium cyclotriphosphate (NH₄)P₃O₉, ammonium cyclotetraphosphate [P^IV? P^IV ? O? ]₂, ammonium cyclotriphosphatophosphonates Ammonium organyldiphosphonates And ammonium diphosphites are prepared in high yields on heating acidic phosphates, phosphonates, and phosphites in urea or urea/ammonium nitrate melts. The mechanism of the dehydration of phosphorus compounds containing POH groups in molten urea is discussed.     

Kinetics of recombination,dismutation, and disproportionation reactions involving neutral ketyl radicals and radical anions

The kinetics of fast elementary recombination of neutral ketyl radicals of benzophenone and its four derivatives (BPH?), the dismutation of benzophenone radical anions, the disproportionation between BPH? and stable nitroxyl radicals, ( ), and the electron transfer have been investigated in both individual solvents and binary mixtures of different viscosities. Reaction (1) for unsubstituted BPH in water, water glycerol, and n-hexane is controlled by diffusion with 2k₁ ? k_diff. In aliphatic alcohols and toluene, which form solvation complexes with BPH?, reaction (1) is diffusion-enhanced and activation-controlled, respectively, with 2k₁ < k_diff. In a viscous solvent such as 1-propanol–glycerol mixture (100 ? η ? 450 cP) reaction (1) is diffusion-controlled. Reaction (2) in alkaline 1-propanol and alkaline 1-propanol–glycerol mixture is activation controlled. The rates of reactions (3) and (4) for benzophenone radicals and nitroxyl radicals of the imidazoline series decrease as the viscosity of the water–glycerol and 1-propanol–glycerol mixtures is increased. The reactions are molecular mobility limited; nevertheless, the numerical values of k₃ (k₄) are 2–6 times as small as the corresponding k_diff values due to the low steric factor of the reactions (therefore called pseudodiffusion-controlled reactions). The theoretical estimates of k₃ (k₄) are in good agreement with the experimental results. The elimination of spin forbiddance in the process of radical recombination in viscous solvents is discussed.     

Studies on polyyne polymers containing transition metals in the main chain. IV. Polymer synthesis by oxidative coupling of transition metal-bis(acetylide) complexes

The metal-polyyne polymers consisting of transition metals and conjugated tetrayne systems where M represents ? Pt(PBu₃)₂? or ? Pd(PBu₃)₂? moiety were prepared by the oxidative coupling method and characterized by spectral analysis, associated with novel depolymerization giving binuclear transition metal complexes, and      

The loss of CH3⋅ from some unsaturated dithioesters

The mechanism for the loss of CH₃? (and C₂H₅?) from the molecular ions of some unsaturated dithioesters of the type with n=0, 1, 2, has been studied. Based on first field free region metastable ion characteristics it is proposed that 1,3-dithiolium type product ions are generated. Deuterium labelling experiments indicated that the molecular ions of the 2-alkenyl alkanedithioates undergo a rearrangement prior to fragmentation which resembles the [3,3]sigmatropic rearrangement in solution chemistry.     

The reaction of 3,4‐diamino‐1,2,5‐oxadiazoles with formaldehyde

The compounds 5,6‐dihydro‐4H‐imidazo[4,5‐c][1,2,5]oxadiazole ( 3a , R?H), 4,6,10,12‐tetramethyl‐5,6,11,12‐tetrahydro‐4H,10H‐bis(1,2,5)oxadiazolo[3,4‐d:3′,4′‐I][1,3,6,8]tetraazecine ( 4b , R?CH₃), N³,N³′‐methylenebis‐3,4‐diamino‐1,2,5‐oxadiazole ( 5a , R?H) and N³,N³′‐methylenebis(N,N′‐dimethyl‐3,4‐diamino‐1,2,5‐oxadiazolee) ( 5b , R?CH₃) were synthesized from the reaction of formaldehyde with 3,4‐diamino‐1,2,5‐oxadiazole and N,N′‐3,4‐dimethylamino‐1,2,5‐oxadiazole in an acetonitrile.     

How Much Water Does Calcined Gypsum Contain?

Ordered water : Gypsum has been used for construction for millennia. The structure and water content of calcined gypsum, CaSO₄?0.5 H₂O, has been under discussion until now: single‐crystal structure analysis (see picture: S yellow, Ca gray, O blue, H red) provides an ordered model that is confirmed by DFT calculations.

     

Structural studies of polyformals. II. Crystal structure of poly-1,3-dioxolane: Modification II1

The structure of poly-1,3-dioxolane, [? OCH₂O? (CH₂)₂? ]_n was studied by x-ray diffraction and infrared spectroscopy. Three crystal modifications were found. The crystal structure of modification II was determined: four molecular chains of glide type pass through the orthorhombic unit cell; Pbca-D_2h¹⁵, a = 9.07 Å, b = 7.79 Å, and c (fiber axis) = 9.85Å. The molecular conformation is The molecular chain consists of regular head-to-tail sequences. This fact shows that the ring opening of 1,3-dioxolane occurs exclusively at the same type of CO bond in the cationic polymerization, just as in the case of 1,3-dioxepane.     

Hindered rotation in thioamides—II

The NMR spectra for a series of amides and thioamides of type where R = CH₃, C₆H₅ and C₆H₅CH₂, were investigated from ?60° to 150°C. The Arrhenius activation energies, E_a, for the normal amide equilibration were determined by the W_½ method and the values range from 15.4 to 20.9 Kcal/mole. The three thioamides, compounds ( 2 ), ( 4 ) and ( 6 ) yield spectra showing a second, low temperature, equilibration. This exchange was first studied by Siddall and co-workers and they interpreted the spectral changes in terms of population changes of the conformational isomers about the N? CH bonds. They assumed strong interaction of nitrogen alkyl groups which gave rise to three low energy dl pairs of isomers. Their results, however, as well as those obtained for similar compounds reported herein, show only two sets of patterns at low temperatures. These spectra suggest a first order, A?B, type equilibration where P_A≠P_B. An alternative assignment based upon the following classification of steric effects of S, R, R′ and R″, is suggested; (1) a strong interaction of the sulfur atom with the adjacent alkyl group on the nitrogen atom, R′, (2) a somewhat weaker interaction of R with the adjacent nitrogen alkyl group R″ and (3) a still weaker interaction of the two nitrogen alkyl groups, R′ and R″. This leads to four isomers, two dl pairs, C₁T₄, C₆T₃ and C₁T₆, C₆T₃, which are expected to have a lower energy than the rest and the first pair is preferred. The W_½ method of measuring exchange rates was extended to cover A?B equilibrations, where P_A≠P_B. The results indicate an accuracy that is not significantly lower than that obtained by the more elaborate total line shape analysis.     

P. Melchiorre

?My most exciting discovery to date has been always the last one (or better still, the next one). The biggest challenge facing scientists is the responsible use of knowledge and scientific power for the betterment of humanity. …?“ This and more about P. Melchiorre can be found on page 3389.

     

Étude des Paramètres de Résonance Magnétique Nucléaire et de la Stéréochimie de Thiono-2 R-2 Dithiaphosphorinanes-1,3,2

The ¹H, ¹³C and ³¹P n.m.r. spectra of eleven 2-R-2-thiono-1,3,2-dithiaphosphorinanes with various R groups attached to the phosphorus atom have been recorded and analysed. In the compounds where R=Cl, OMe or N, the molecule adopts a chair conformation with the R group axially oriented. When the molecule adopts a chair conformation with equatorially oriented R. In the case of the derivatives with R=phenyl, Me, N(Me)₂ or NHt-Bu, a chair–chair conformational equilibrium was observed. The hindered rotation about the P? N bond was also examined in the derivative with      

HNO,an Intermediate in (Light-induced) Rearrangement Reactions of Nitrosooxy Compounds and Nitrosamines

IR-spectroscopic investigations of light-induced rearrangement reactions of nitrosooxymethane (CH³ONO³), nitrosooxyethane (CH₃CH₂ONO) and N,N-dimethylnitrosamine ((CH₃)₂NNO) in low-temperature rare-gas matrices have established that these molecules are transformed in two photolysis steps to the previously unknown C-nitroso compounds nitrosomethanol (CH₂(OH)(NO)), 1-nitrosoethanol (CH₃CH(OH)(NO)), and methyl(nitrosomethyl)amine CH₂(NO)(NH)(CH₃). Evidence for a similar rearrangement reaction has been advanced for N-Nitrosopyrrolidine which is converted to C-nitrosopyrrolidine . The matrix-isolation technique in combination with wavelength-selective irradiation allowed to trap and characterize an intermediate of rearrangement which revealed to be nitroxyl (HNO) complex (CH₂…HNO, CH₃CHO…HNO, CH₃N = CH₂…HNO, and ). Since these findings have a close resemblance with rearrangement reactions of more complex nitrosooxy compounds, nitrosamines, or nitrosohydrazines used in organic synthesis, it is suggested that also in these reactions nitroxyl is present as an intermediate species.     

The pyrolyses of tri- and tetramethylethylene in the presence of nitric oxide

The pyrolyses of trimethylethylene and tetramethylethylene have been investigated in the presence and absence of nitric oxide. It appears that apart from a unimolecular split, e.g., a disproportionation reaction such as may play an important role in initiation. Nitric oxide had no effect on H₂ production, which is probably a molecular process. There was similar behavior of both compounds in the presence of NO, indicating that the olefinic hydrogen atom does not play a decisive role. Other aspects of the mechanisms are discussed.     

Effect of gegen ion in cationic polymerization and copolymerization of trioxane

p-Chlorophenyldiazonium hexafluorophosphate has been reported to be a superior catalyst for cationic polymerization and copolymerization of trioxane as compared to boron trifluoride dibutyl etherate (BF₃·Bu₂O)¹. In the present investigation the effect of anions derived from elements in Group VA, AsF and SbF, has been ascertained. It has been concluded that p-chlorophenyldiazonium hexafluoroarsenate is also a superior catalyst to boron trifluoride dibutyletherate (BF₃·Bu₂O), while p-chlorophenyl-diazonium hexafluoroantimonate is inferior. Copolymers with the highest polymer yield (>95%) and molecular weight (intrinsic viscosity = 4 to 5) were obtained with Simple dependences on catalyst concentration have been observed to hold for a wide catalyst concentration range ([M]/[C]) = (1 to 20) × 10⁵: For the same relationships hold. However, the polymer yield (75%) and molecular weights (intrinsic viscosity ?1) are considerably lower while the extent of chain transfer is higher. Furthermore, the polymerization proceeds with explosive violence. The quantitative aspects resulting from polymerization, for the most part, can be interpreted in terms of the extent of dissociation of the propagating ions.     

Transition Metal Complexes with Bidentate Ligands Spanning trans-Positions. XII. Steric effects in the kinetics and mechanism of substitutions at hydride and methyl bisphosphine platinum (II) complexes

Ligand substitution reactions on square-planar platinum (II) complexes of the types trans-[PtRXL₂], trans-[PtR(4-PADA)L₂][BF₄], trans-[PtRX( ) and trans-[PtR(4-PADA)( )][BF₄] R=H, Me; X=Cl^?, I^?; L=PEt₃, bis(3-trifluoromethyl-phenyl)benzylphosphine ( 4 ), =the trans-spanning 2,11-bis[bis(3-trifluoro-methylphenyl)phosphinomethyl]benzo [c]phenanthrene ( 3 ); 4-PADA (=pyridine-4-azo-4′-(N, N-dimethyl)aniline have been studied at 30° using stopped-flow and conventional spectrophotometry, methanol as solvent, and 2.5 × 10^?2 M ionic strength (LiClO₄ as supporting electrolyte). 4-PADA was used as indicator ligand, as its absorption spectrum differs from those spectra where it is complexed. The expected steric effects of the bulky ligands, especially of 3 , on the rates and mechanisms of all the reactions studied are small. All reactions take place by the usual two-term rate law. Noteworthy, for the complexes with the bulky ligands 3 and 4 , the direct reaction path with the entering nucleophile is predominant. There is no preference for a solvent or dissociative path. The reactivity order for the hydride complexes is trans-[PtHX (PEt₃)₂]<trans-[PtHX( 4 )₂]<trans-[PtHX ( 3 )]. However, for the corresponding methyl complexes, there is some retardation by ligand 3 , probably due to an interaction between the methyl group and the hydrocarbon moiety of 3 , which inhibits the fluxional behavior of this ligand. The results have some relevance for the understanding of olefin-insertion reactions of hydride complexes containing these phosphine ligands.     

Etude de la Protonation du Groupe Amide par Resonance Magnetique Nucleaire. Comportement des Anilides Substitues en Milieu Acide Concentre

Five substituted anilides of general formula were studied in acidic media (H₂SO₄? MeOH and HSO₃Cl? Me₂CO). The unsolved problem of the protonation site (O-protonation and N-protonation) is discussed in terms of the observed NMR shifts [(δNH) and δ(CO? H)] taking into account several factors including hydrogen bonding and solvent effects. New dramatic evidence is presented of N-protonation of the amide group; in the case of 2,4-dinitro formanilide, the NO₂ groups in the molecule enhance the relative basicity of the nitrogen atom in such a way that the amount of N-protonated amide can be detected. N-protonation is a function of the acidity, showing a maximum in the region of 40 to 50%.