Disilicon Complexes with Two Hexacoordinate Si Atoms: Paddlewheel‐Shaped Isomers with (ClN4)Si?Si(S4Cl) and (ClN2S2)Si?Si(S2N2Cl) Skeletons

The reaction of 1‐methyl‐3‐trimethylsilylimidazoline‐2‐thione with hexachlorodisilane proceeds toward substitution of four of the disilane Cl atoms during the formation of disilicon complexes with two neighboring hexacoordinate Si atoms. The N,S‐bidentate methimazolide moieties adopt a buttressing role, thus forming paddlewheel‐shaped complexes of the type ClSi(μ‐mt)₄SiCl (mt=methimazolyl). Most interestingly, three isomers (i.e., with (ClN₄)Si? Si(S₄Cl), (ClN₃S)Si? Si(S₃NCl), and (ClN₂S₂)Si? Si(S₂N₂Cl) skeletons as so‐called (4,0), (3,1), and cis‐(2,2) paddlewheels) were detected in solution by using ²⁹Si NMR spectroscopic analysis. Two of these isomers could be isolated as crystalline solids, thus allowing their molecular structures to be analyzed by using X‐ray diffraction studies. In accord with time‐dependent NMR spectroscopy, computational analyses proved the cis‐(2,2) isomer with a (ClN₂S₂)Si? Si(S₂N₂Cl) skeleton to be the most stable. The compounds presented herein are the first examples of crystallographically evidenced disilicon complexes with two Si? Si‐bonded octahedrally coordinated Si atoms and representatives of the still scarcely explored class of Si coordination compounds with sulfur donor atoms.     

Umsetzungen von Thiazylhalogeniden XSN (X = F,Cl) mit perfluorierten Iminen Rf2NH (Rf = F,CF3, CF3S, (CF3)2C, (CF3)2 S): Versuche zur Darstellung von Aminothiazylen (N?SN)

Reactions of Thiazyl Halides XSN (X = F, Cl) with Perfluorinated Imines R_f2 NH (R_f = F, CF₃, CF₃S, (CF₃)₂C?, (CF₃)₂S?): Attempted Preparations of Aminothiazyls (?N? S?N) Thiazyl halides or their precursors Cl₃S₃N₃ and FC(O)N?SF₂ react with perfluoro imines to provide the corresponding aminothiazyls as unstable and reactive intermediates. While with HNF₂ or KF · HNF₂ the final products N₂F₄ and S₄N₄ are formed, [(CF₃)₂N]₂Hg reacts with Cl₃S₃N₃ to give CF₃N?CF₂, FSN, and HgCl₂. The expected product CF₃SN?S?NSCF₃ ( 4 ) is obtained from (CF₃S)₂NH or Hg[N(SCF₃)₂]₂ and FSN probably via (CF₃S)₂ NSN. Surprisingly, (CF₃)₂C?NLi forms with ClSN, Cl₃S₃N₃ or [S₃N₂Cl]Cl in the presence of NH₄Cl 4,5-Dihydro-3,3,5,5-tetrakistrifluoromethyl-3H-1λ⁴,2,4,6-thiatriazine ( 6 ) and (CF₃)₂C?NS_xN?C(CF₃)₂ (X = 1, 2) ( 7a, b ) as byproducts. A CsF catalyzed reaction at 70 to 80°C between (CF₃)₂C?NLi and FSN provides low yields of (CF₃)₂C?N? S? N?S?NCF(CF₃)₂ ( 8 ) together with 7a, b. The latter are the only products without CsF. When (CF₃)₂S?NH is treated with FSN, the compounds CF₃SCF₃, S₄N₄, and N₂ are identified. It is shown by ¹⁹F and ¹⁴N-n.m.r. spectroscopy that (CF₃)S?NSN is an unstable intermediate.     

Syntheses and Structures of S4N4(OCH3)2 and CH3OS4N4(O)Cl

The reaction of S₄N₄Cl₂ with CH₃OH gives S₄N₄(OCH₃)₂, a simple dimethoxoderivative of S₄N₄. Its overall geometry is analogous to other compounds of the S₄N₄X₂ type. The chlorination of S₄N₄(OCH₃)₂ leads to the oxidation of one sulfur atom to S^VI and CH₃OS₄N₄(O)Cl is formed. The compounds were characterized by ir spectroscopy and their crystal structures were determined from single crystal diffraction data collected at ?153°C. The presence of S^VI in the molecule of CH₃OS₄N₄(O)Cl is manifested by a marked shortening of the bonds formed by this atom as compared with S₄N₄Cl₂ and S₄N₄(OCH₃)₂.     

Reactions of S4N4 with diphosphines,Ph2P(X)PPh2 (X = NC4H8N,CH2CH2)

Reactions of S₄N₄ with diphosphines, Ph₂P(X)PPh₂ (X = NC₄H₈N, CH₂CH₂) have resulted in the isolation of N₃S₃? NPPh₂(X)Ph₂PN? S₃N₃ (X = NC₄H₈N, CH₂CH₂), (S)PPh₂(CH₂CH₂)Ph₂PN? S₃N₃, and (S)PPh₂NC₄H₈NPh₂P(S) as new compounds. These heterocycles have been characterized by analytical and spectroscopic (IR, UV-VIS, ¹H and ³¹P-NMR, and MS) techniques.     

Über die Umsetzung von Thiazylfluorid mit mehrfunktionellen Stickstoffderivaten

Reaction of Thiazylfluoride with Multifunctional Nitrogen Derivatives From the reaction of NSF 1 with LiN(SiMe₃)R′ (R′ = CMe₃, SiMe₃), linear [e. g. (Me₃C? N?S?N? )₂S ( 11 ), Me₃C? N?S?N? CMe₃ ( 14 ), Me₃Si? N?S?N? SiMe₃ ( 17 ), (Me₃Si)₂N? S? N?S?N? SiMe₃ ( 19 )] and cyclic thiazenes (S₄N₅F ( 22 )) are isolated, (S₃N₄)_n ( 23 ) is obtained in high yield from 1 and 17 (in the ratio 2:1). Possible structures for 23 are discussed; the reaction of 23 with AsF₅ gives S₄N₄ · AsF₅ ( 24 ) in a hitherto unknown modification. Possible reactions of the terminal SN groups are discussed and the structures of 11 and 24 are reported.     

Spektroskopische Untersuchungen an Siliciumverbindungen. XXXI. Schwingungsverhalten von p-substituierten N,N-Bistrimethylsilylanilinen

The following p-substituted N,N-bis-trimethlsilyl anilines p-X? C₆H₄? N[Si(CH₃)₃]₂ are prepared by silylation of free amines: X = H, CH₃, C₂H₅, CH₃O, CH₃CO, F, Cl, Br, J, CN, C₆H_S, (CH₃)₃SiO, and [(CH₃)₃Si]₂N, and the isotopic derivatives C₆H₅? ¹⁵N[Si(CH₃)₃]₂ and C₆D₅N[Si(CH₃)₃]₂. The vibrational spectra are reported and assigned. The molecular symmetry of p-[(CH₃)₃Si]₂N? C₆H₄? N[Si(CH₃)₃]₂ is determined. The influence of the mass of the substituents X on the positions of the ν_sSiNSi vibrational frequencies is discussed.     

Synthese und Röntgenstrukturanalyse von S4N4-Derivaten mit drei- und vierfach koordinierten Schwefelatomen

CF₃SO₂N?SCl₂ reagiert mit (CH₃)₂S[NSi(CH₃)₃]₂, (C₄H₈)S[NSi(CH₃)₃]₂ oder (C₅H₁₀)S[NSi(CH₃)₃]₂ unter Trimethylchlorsilanabspaltung zu den achtgliedrigen S₄N₄-Derivaten S₄N₄(NSO₂CF₃)₂(CH₃)₄ 3 , S₄N₄(NSO₂CF₃)₂(C₄H₈)₂ 4a und S₄N₄(NSO₂CF₃)₂(C₅H_{1 0})₂ 4b . In den achtgliedrigen SN-Ringen haben die Schwefelatome die Koordinationszahl 3 und 4. Die Röntgenstrukturanalyse von 4a ergab eine Sessel-Konformation. 4a kristallisiert orthorhombisch in der Raumgruppe Pna2₁ mit a = 17,641(4), b = 6,406(2), c = 19,130(4) Å, d_x = 1,815 g cm^?3 und Z = 4. Die mittleren S? N-Abstände betragen an den vierfach koordinierten Schwefelatomen 1,597 Å und an den Schwefelatomen mit der Koordinationszahl 3 1,650 Å. CF₃SO₂N? SCl₂ reagiert mit trimethylzinnhaltigen S? N-Verbindungen zum bekannten CF₃SO₂N[Sn(CH₃)₃]S(CH₃)NSO₂CF₃ und Dimethylzinndichlorid. Synthesis and X-Ray Structure Analysis of S₄N₄-Derivatives with Threefold and Fourfold Coordinated Sulfur Atoms CF₃SO₂N?SCl₂ reacts with (CH₃)₂S[NSi(CH₃)₃]₂, (C₄H₈)S[NSi(CH₃)₃]₂ or (C₅H₁₀S[NSi(CH₃)₂]₂ under elimination of (CH₃)₃SiCl to yield the eight-membered S₄N₄ derivatives S₄N₄?NSO₂CF₃)₂(CH₃)₄, 3 , S₄N₄(NSO₂CF₃)₂(C₄H₈)₂ 4a und S₄N₄(NSO₂CF₃)₂(C₅H_{1 0})₂ 4b . In the eight-membered SN-rings the sulfur atoms have the coordination number 3 and 4. The X-ray structure analysis of 4a revealed a chair conformation. 4a crystallizes in the orthorhombic space group Pna2₁ with a = 17.641(4), b = 6.406(2), c = 19.130(4) Å, d_x = 1.815 g cm^?3, and Z = 4. The average S? N distance was found to be 1.597 Å at fourfold coordinated sulfur atoms and 1.650 Å at sulfur with coordination number 3. CF₃SO₂N=SCl₂ reacts with trimethyl tin-containing S? N compounds to the known CF₃SO₂N[Sn(CH₃)₃]S(CH₃)NSO₂CF₃ and dimethyl tin dichloride.     

Über Reaktionen des P4S10 mit siliciumorganischen Verbindungen

Reactions of P₄S₁₀ with Organosilicon Compounds P₄S₁₀ ( 1 ) can be degraded with silicon-nitrogen compounds. 1 reacts with (CH₃)₃Si? N(CH₃)₂ ( 2 a ) and (CH₃)₃Si? N(C₂H₅)₂ ( 2 b ) to yield S?P[N(CH₃)₂]₂SSi(CH₃)₃ ( 3 a ) and ( 3 b ). By the reaction of 1 with [(CH₃)₃Si]₂S ( 4 ) S?P[S? Si(CH₃)₃]₃ ( 6 ) is formed in high yield. (C₆H₅PS₂)₂ ( 7 ) was used as a model to investigate the course of the reaction. This leads to C₆H₅P(S)? [N(CH₃)₂]SSi(CH₃)₃ ( 9 ) and C₆H₅P(S)[SSi(CH₃)₃]₂ ( 10 ). The reaction mechanism will be discussed. The n.m.r. data and mass spectra are reported.     

Elektrochemische Synthesen. XXIII. Elektrochemische und EPR-spektroskopische Untersuchung des Redoxverhaltens von (SN)+ und [S3N3]−

Electrochemical Syntheses. XXIII. Electrochemical and EPR-Spectroscopic Investigation of the Redox Behaviour of (SN)⁺ and [S₃N₃]^? The eventual syntheses of SN^. and (S₃N₃)^. by electrochemical reduction or oxidation, respectively, starting from (SN)⁺[SbF₆]^? and (PPN)⁺[S₃N₃]^? were checked by e.p.r. spectroscopy. Only the reduction of (SN)[SbF₆] yielded detectable paramagnetic species: the long-known (S₃N₂)^+. and a radical, the e.p.r. signal of which is a quintet of triplets. This signal is not obtained by electro-chemical oxidation of CF₃CO? N?(S₃N₂) or FSO₂? N?(S₃N₂).     

3‐Rhoda‐1,2‐diazacyclopentanes: A Series of Novel Metallacycle Complexes Derived From CN Functionalization of Ethylene

Rh‐containing metallacycles, [(TPA)Rh^III(κ²‐(C,N)‐CH₂CH₂(NR)₂‐]Cl; TPA=N,N,N,N‐tris(2‐pyridylmethyl)amine have been accessed through treatment of the Rh^I ethylene complex, [(TPA)Rh(η²‐CH₂CH₂)]Cl ([ 1 ]Cl) with substituted diazenes. We show this methodology to be tolerant of electron‐deficient azo compounds including azo diesters (RCO₂N?NCO₂R; R=Et [ 3 ]Cl, R=iPr [ 4 ]Cl, R=tBu [ 5 ]Cl, and R=Bn [ 6 ]Cl) and a cyclic azo diamide: 4‐phenyl‐1,2,4‐triazole‐3,5‐dione (PTAD), [ 7 ]Cl. The latter complex features two ortho‐fused ring systems and constitutes the first 3‐rhoda‐1,2‐diazabicyclo[3.3.0]octane. Preliminary evidence suggests that these complexes result from N–N coordination followed by insertion of ethylene into a [Rh]?N bond. In terms of reactivity, [ 3 ]Cl and [ 4 ]Cl successfully undergo ring‐opening using p‐toluenesulfonic acid, affording the Rh chlorides, [(TPA)Rh^III(Cl)(κ¹‐(C)‐CH₂CH₂(NCO₂R)(NHCO₂R)]OTs; [ 13 ]OTs and [ 14 ]OTs. Deprotection of [ 5 ]Cl using trifluoroacetic acid was also found to give an ethyl substituted, end‐on coordinated diazene [(TPA)Rh^III(κ²‐(C,N)‐CH₂CH₂(NH)₂‐]⁺ [ 16 ]Cl, a hitherto unreported motif. Treatment of [ 16 ]Cl with acetyl chloride resulted in the bisacetylated adduct [(TPA)Rh^III(κ²‐(C,N)‐CH₂CH₂(NAc)₂‐]⁺, [ 17 ]Cl. Treatment of [ 1 ]Cl with AcN?NAc did not give the Rh?N insertion product, but instead the N,O‐chelated complex [(TPA)Rh^I ( κ²‐(O,N)‐CH₃(CO)(NH)(N?C(CH₃)(OCH?CH₂))]Cl [ 23 ]Cl, presumably through insertion of ethylene into a [Rh]?O bond.     

Multicentre hydrogen bonds in a 2:1 aryl­sulfonyl­imidazol­one ­hydro­chloride salt

The title compound, (S)‐(+)‐4‐[5‐(2‐oxo‐4,5‐di­hydro­imidazol‐1‐yl­sulfonyl)­indolin‐1‐yl­carbonyl]­anilinium chloride (S)‐(+)‐1‐[1‐(4‐amino­benzoyl)­indoline‐5‐sulfonyl]‐4‐phenyl‐4,5‐di­hydro­imidazol‐2‐one, C₂₄H₂₃N₄O₄S⁺·Cl^?·C₂₄H₂₂N₄O₄S, crystallizes in space group C2 from a CH₃OH/CH₂Cl₂ solution. In the crystal structure, there are two different conformers with their terminal C₆ aromatic rings mutually oriented at angles of 67.69 (14) and 61.16 (15)°. The distances of the terminal N atoms (of the two conformers) from the chloride ion are 3.110 (4) and 3.502 (4) Å. There are eight distinct hydrogen bonds, i.e. four N—H?Cl, three N—H?O and one N—H?N, with one N—H group involved in a bifurcated hydrogen bond with two acceptors sharing the H atom. C—H?O contacts assist in the overall hydrogen‐bonding process.     

Phosphaniminato-Komplexe des Schwefels. Synthese und Kristallstrukturen von [O3SS(NPPh3)2] · CH3CN, [SO(NPPh3)2] und [SCl(NPMe3)2]Cl

Phosphorane Iminato Complexes of Sulfur. Syntheses and Crystal Structures of [O₃SS(NPPh₃)₂] · CH₃CN, [SO(NPPh₃)₂], and [SCl(NPMe₃)₂]Cl The title compounds have been prepared by the reaction of Me₃SiNPPh₃ with SO₂ and SOCl₂, respectively, and by the reaction of Me₃SiNPMe₃ with S₂Cl₂. They form colourless, moisture sensitive crystals, which were characterized by IR spectroscopy and by crystal structure determinations. [O₃SS((NPPh₃)₂)] · CH₃CN : Space group Pca2₁, Z = 4, structure solution with 4016 observed unique reflections, R = 0.050. Lattice dimensions at ?60°C: a = 1865.1, b = 1168.4, c = 1569.0 pm. The compound has a zwitterionic structure with a S? S bond length of 218.2 pm and bond lengths S? N of 161.2 and P? N of 160.1 pm. [SO(NPPh₃)₂] : Space group P2₁/c, Z = 4, structure solution with 2854 observed unique reflections, R = 0.113. Lattice dimensions at ?50°C: a = 1173.1, b = 1585.6, c = 1619.2 pm, b? = 98.13°. The compound forms monomeric molecules, in which the positions of S and N atoms are disordered in two positions. The bond lengths are S? N 166 pm and P? N 163 pm in average. [SCl(NPMe₃)₂]Cl : Space group P1 , Z = 2, structure solution with 2416 observed unique reflections, R = 0.038. Lattice dimensions at 20°C: a = 613.2, b = 1030.3, c = 1111.4 pm, α = 88.48°, b? = 88.01°, γ = 83.10°. The compound forms ions [SCl(NPMe₃)₂]⁺ and Cl^?. In the cation the sulfur atom is ?-tetrahedrally coordinated with a long S? Cl distance of 246.9 pm and bond lengths S? N of 155.3 pm and P? N of 164.3 pm in average.     

Trivalent-pentavalente Phosphorverbindungen/Phosphazene. IV. Darstellung und Eigenschaften neuer N-silylierter Diphosphazene

Trivalent-Pentavalent Phosphorus Compounds/Phosphazenes. IV. Preparation and Properties of New N-silylated Diphosphazenes Phosphazeno-phosphanes, R₃P = N? P(OR′) ₂ (R = CH₃, N(CH₃)₂; R′ = CH₂? CF₃) react with trimethylazido silane to give N-silylated diphosphazenes, R₃P = N? P(OR′)₂ = N? Si(CH₃)₃ compounds decompose by atmospherical air to phosphazeno-phosphonamidic acid esters, R₃ P?N? P(O)(O? CH₂? CF₃)(NH₂). Thermolysis of diphosphazene R₃P = N? P(OR′) ₂ = N? Si(CH₃)₃ (R = CH₃, R′ = CH₂? CF₃) produces phosphazenyl-phosphazenes [N?P(N?P(CH₃)₃)OR′] _n. The compounds are characterized by elementary analysis, IR-, ¹H_-, ²⁹Si-, ³¹P-n.m.r., and mass spectroscopy.     

A Series of Isolable Silanoic Thio‐, Seleno‐, and Telluroesters (LSi(X)OR) with Donor‐Supported SiX Double Bonds (L=β‐Diketiminate; X=S,Se, Te)

The first silicon analogues of carbonic (carboxylic) esters, the silanoic thio‐, seleno‐, and tellurosilylesters 3 (Si?S), 4 (Si?Se), and 5 (Si?Te), were prepared and isolated in crystalline form in high yield. These thermally robust compounds are easily accessible by direct reaction of the stable siloxysilylene L(Si:)OSi(H)L′ 2 (L=HC(CMe)₂[N(aryl)₂], L′=CH[(C?CH₂)‐CMe][N(aryl)]₂; aryl=2,6‐iPr₂C₆H₃) with the respective elemental chalcogen. The novel compounds were fully characterized by methods including multinuclear NMR spectroscopy and single‐crystal X‐ray diffraction analysis. Owing to intramolecular N→Si donor–acceptor support of the Si?X moieties (X=S, Se, Te), these compounds have a classical valence‐bond N⁺–Si–X^? resonance betaine structure. At the same time, they also display a relatively strong nonclassical Si?X π‐bonding interaction between the chalcogen lone‐pair electrons (n_π donor orbitals) and two antibonding Si? N orbitals (σ*_π acceptor orbitals mainly located at silicon), which was shown by IR and UV/Vis spectroscopy. Accordingly, the Si?X bonds in the chalcogenoesters are 7.4 ( 3 ), 6.7 ( 4 ), and 6.9 % ( 5 ) shorter than the corresponding Si? X single bonds and, thus, only a little longer than those in electronically less disturbed Si?X systems (“heavier” ketones).     

Synthesis,characterization, and structures of 1-(9-Fluorenyl)-germatrane and 1-(Phenylacetylenyl)germatrane

Syntheses of the title compounds, viz. N(CH₂CH₂O)₃GeY ( 2 Y?Fluorenyl; 4 Y?PhC?C) by the reaction of X₃GeY ( 1 Y?Fluorenyl, X?Br; 5 Y?PhC?C, X?Cl) with N(CH₂CH₂OSnR₃)₃ ( 3 R?Et; 6 R?Bu) are reported including the preparation of the new compound 1 . Identity and structures were established by elemental analyses, ¹H and ¹³C NMR spectroscopy. 2 and 4 were characterized by mass spectrometry. Single crystal structures of 1 , 2 and 4 were determined by X-ray diffraction methods.     

Über Fluoride des zweiwertigen Eisens: Cs7Fe4F15

Concerning the Cleavage of Si? C Bonds in Si-methylated Carbosilanes The chances for the cleavage of Si? Me bonds (Me ? CH₃) and Si? C? Si bonds in their molecular skeletons using ICl or ICl/AlBr₃ are examined in 13 carbosilanes; i. e. (Me₂Si? CH₂)₃ 1 , 1,3,5,7-tetramethyl-1,3,5,7-tetrasilaadamantane 2 , (Me₃Si? CH₂)₂SiMe₂ 3 , HC(SiMe₃)₃ 4 , the 1,3,5,7-tetrasilaadamantane. carrying bhe ? CH₂? SiMe, group at one Si atom 5 , the 1,3,5-trisilacyclohexane, carrying the ? CH₂? SiNe₃ group 6 , three derivatives of the 1,3,5-trisilacyclohexane, carrying SiMe₃ groups at skeletal C atoms 7 , 8 , 9 , three derivatives of the 1,3,5-trisilacyclohexane, carrying CH₃, groups at skeletal C atoms 10 10, 11 , 12 and 13 , derived from (Me₂Si? CH₂)₃ having one ?CBr₂ group. Using ICl one Me group at each Si atom in 1 can be split off successively, finally yielding (ClMeSi? CH₂)₃. 2 is transformed to the Si-chlorinated 1,3,5,7-tetrasilaadamantane. 3 , treated with ICl yields (ClMeSi? CH₂)₂SiMeCl, as 4 forms HC(SiMe₂Cl)₃. Higher chlorinated compounds can be obtained by using ICl and AlBr₃ in catalytic amounts. Thus 1 leads to (Cl₂Si? CH₂)₃, no ring-opening is observed. However, in the reaction of 1 with HBr/AlBr₃ bromination at the Si atoms and ring-opening (ratio 1:1) proceed coincidently. The reaction of either 3 or (ClMe₂Si? CH₂)₂SiMeCl with ICl/AlBr₃ leads to (Cl₂MeSi? CH₂)₂SiCl₂, and (Me₃Si)₂CH₃ forms (Cl₂MeSi? )₂CH₂ similarly. The ? CH₂? SiMe₃ group in 5 and 6 is not cleaved off by ICl; the introduction of a Cl group at each Si atom is observed instead. Furthermore, 6 undergoes cleavage (≈8%) of the Si? C ring adjacent to the chain-substituted Si atom [formation of ClMe₂Si? (CH₂? SiMeCl)₂CH₂? SiMe₂? CH₂Cl]. 7 , 8 , 9 (having the ? SiMe₃ group at the C atoms) react with ICl by splitting off one Si? Me group from each Si atom. In 7 we also observe the ring-opening to an amount of ≈25% [formation of (ClMe₂Si)CH₂? SiMeCl? CH₂? SiMe₂? CH₂Cl]. In ₈ (having two CH(SiMe₃) groups the ring-opening reaction is reduced to about 5% [formation of ClMe₂? CH(SiMe₂Cl)? SiMeCl? CH(SiMe₂Cl)? SiMe₂? CH₂Cl], while in 9 (having three CH(SiMe₃) groups) it is not found at all. In 10 , 11 , 12 (having the CH₃ group at the C atoms) ICl substitutes one Me group (formation of SiCl) at each Si atom (no ring-opening). The CBr₂ group reduces the reactivity of 13 towards ICl. Only the split-off of one Me group at the Si atom in para-position to the CBr₂ group is observed. Using ICl/AlBr₃ higher chlorinated derivatives are obtained (no ring-opening). Most of the mentioned compounds were identified via their Si? H-containing derivatives, thus facilitating the chromatographic separation as well as the ¹H-NMR-spectroscopic investigations.     

1λ6,2,4-Thiadiazetidine und 1,2λ6,3-Oxathiazetidine

1λ⁶,2,4-Thiadiazetidines and 1,2λ⁶,3-Oxathiazetidines From the reaction of the sulfur triimides (RN?)₃S ( 2a R?(CH₃)₃C, 2b R?(CH₃)₃Si) with pentafluoroazapropene ( 11 ) the appropriate 1λ⁶,2,4 thiadiazetidines ( 13a, 13b ) are formed, while from ClSO₂N?CCl₂ ( 14 ) and 2a (CH₃)₃C? N?C?N? SO₂Cl ( 17 ) is isolated. 2b and hexafluoroacetone ( 18 ) give the rather unstable 1,2λ⁶,3-oxathiazetidine ( 20 ).     

Photolysis of dimethylnitrosamine in the gas phase

Photodecomposition of dimethylnitrosamine in the gas phase ( ～ 1 Torr) has been investigated following irradiation into the S₁ (nπ*) ← S₀ (363.5 nm) and S₂ (ππ*) ← S₀ (248.1 nm) transitions at room temperature. With a quantum yield of unity, excitation into the S₁ state yields the fragments (CH₃)₂N? and NO which then recombine leaving no photoproducts. The addition of O₂ results in only one photoproduct, (CH₃)₂NNO₂. Irradiating into the S₂ state, the products CH₂?N? CH₃, (CH₂?N? CH₃)₃, CH₂?NOH, N₂O, NO, H₂, and N₂ were identified by capillary gas chromatography mass spectrometry. In the presence of N₂ as a buffer gas the photoproducts are only CH₂?N? CH₃, (CH₂?N? CH₃)₃, N₂O, and H₂. For both excitation conditions a mechanism is proposed involving cleavage of the N, N-bond as the main primary photolytic process.     

Thionitrosylkomplexe des Rutheniums. Die Kristallstruktur von (PPh4)2[{RuBr4(NS)}2(μ-N2S2)]

Thionitrosyl Complexes of Ruthenium. Crystal Structure of (PPh₄)₂[{RuBr₄(NS)}₂ (μ-N₂S₂)] Ruthenium trichloride reacts with trithiazyl chloride, yielding cis-RuCl₄ (NS)₂. With triphenylmethylphosphonium chloride this forms the complex [RuCl₄(NS)₂Cl]^? in which a chloride ion is bonded between the sulfur atoms in a chelate manner. With tetraphenylphosphonium bromide, RuCl₄(NS)₂ undergoes a redox reaction that affords (PPh₄)₂[{RuCl₄(NS)}₂(μ-N₂S₂)] which can be transformed to the title compound by the action of trimethylsilyl bromide. The i.r. spectra are reported. The crystal structure of (PPh₄)₂[{RuBr₄(NS)}₂(μ-N₂S₂)] · 4 CH₂X₂ (X ? Cl, Br) was determined with X-ray diffraction data (1534 observed reflexions, R = 0.085). Crystal data: monoclinic, space group P2₁/n, Z = 2, a = 1680.7, b = 1287.0, c = 1706.1 pm and β = 99.97°. The compound consists of tetraphenylphosphonium cations, CH₂Br₂ and CH₂Cl₂ molecules (statistically) and centrosymmetric anions [{RuBr₄(NS)}₂(μ-N₂S₂)]^2? in which the ruthenium atoms are linked via the nitrogen atoms of a planar N₂S₂ ring. In the corresponding trans-positions every Ru atom has a thionitrosyl ligand with a nearly arrangement Ru?N?S with RuN and NS bond lengths of 169 und 151 pm, respectively. Four bromine atoms complete the distorted octahedral coordination of each ruthenium atom. The bromine atoms that are coplanar with the N₂S₂ ring form rather short Br…?S contacts with a mean distance of 317 pm.     

Base Catalysed Racemization of Ethylenediamine-N,N,N′-triacetato-aqua-cobalt(III)

The kinetics of the base catalysed racemization of [Co(EN3A)H₂O]

1 Abbreviations: EN3A^3?=(^?OOCCH₂)₂N(CH₂)₂NHCH₂COO^?; ME3A^3?=(^?OOCCH₂)₂N(CH₂)₂ N(CH₃)CH₂COO^?; EDDA^2?=^?OOCCH₂NH(CH₂)₂NHCH₂COO^?; EDTA^4?=(^?OOCCH₂)₂N(CH₂)₂N(CH₂COO^?)₂;TNTA^4?=(^?OOCCH₂)₂N(CH₂)₃N(CH₃COO^?)₂; HETA^3?=(^?OOCCH₂)₂N(CH₂)₂N(CH₂COO^?)CH₂CH₂OH; en=H₂N(CH₂)₂NH₂; Meen=H₂N(CH₂)₂NHCH₃; sar^?=^?OOCCH₂NHCH₃.

were studied polarimetrically in aqueous buffer solution. The reaction rate is first order in OH^? and in complex, in weakly acidic medium. Activation parameters are ΔH≠=22 kcal · mol^?1, ΔS≠=26 cal · K^?1. The results are discussed in terms of an S_N1CB mechanism involving exchange of the ligand water molecule. The N-methylated analogue [Co(ME3A)H₂O] does not racemize in the pH-range investigated. Loss of optical activity occurs at a rate which is about 1,000 times slower than the racemization of [Co(EN3A)H₂O](60°) and coincides with the decomposition of the complex.