Biochemie und Chemie
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Crystals of [Al(C5H5N)4Cl2][AlCl4] are orthorhombic, Pna21, Z = 4, a = 18.522(7), b = 15.141(5), c = 9.593(3) Å, V = 2690(2) Å3 , Dc = 1.440 g/cm3 . The structure has been solved from 5968 diffractometer measured intensities and refined by full-matrix least squares to Rw(F) = 0.032. The crystal structure shows the complex to be trans-dichloro-tetrakis(pyridine)aluminium(III) tetrachloroaluminat(III). The mean trans Al-Cl-and trans Al-N-distances in the octahedron are 2.279(3) and 2.070(4) Å, respectively. Crystals of Al(C5H5N)3Cl3 are monoclinic, P21/c, Z = 4, a = 7.261(2), b = 29.961(4), c = 8.624(1) Å, β = 98.12(2)°, V -1857(1) Å3 , DC = 1.326 g/cm3 . The structure has been solved from 4707 diffractometer measured intensities and refined to Rw(F) = 0.028. The crystal structure shows octahedral complexes AlCl3·3 (C5H5N) with trans geometry. The Al-N-distance trans to chlorine (2.096(2) Å) is significantly longer than the two other Al-N-distances (mean 2.072(2) Å).
By analyzing the melting point diagrams of some methylhalogenosilane-pyridine systems the existance of the stable addition compounds CH3SiCl3 · 2 py, CH3SiBr3 · 2 py, (CH3)2SiBr2 · py, (CH3)3SiBr · py was proved. In the systems (CH3)2SiCl2/py and (CH3)2SiBr2/py unstable 1:2-complexes are also found. (CH3)3SiCl forms no complexes with pyridine.
With new X-ray data from a crystal of stoichiometric K0.33MoO3 the crystal structure of this compound was refined until R(anisotropic) = 0.023. The characteristic distortion of the Mo-O octahedra is discussed.
Diadamantyldioxetane, trim ethyldioxetane and tetram ethyldioxetane were photolyzed b y light of A > 260 nm . The spectral distribution o f the quanta emitted during photoinduced decom position of dioxatenes was found to be different from fluorescence and phosphorescence o f ketones. Flash photolysis experim ents showed the absorption of an short-lived interm ediate. It was concluded, therefore, that photolysis o fdioxetanes is not a concerted process but involves at least one precursor o f the final product ketone.
The He(I) photoelectron spectra of the following molecules with S·̱·̱̱·̱·̱·̱̱·̱N multiple bonds ... are assigned by radical cation state comparison between the chemically related compounds as well as by MO models based on CNDO calculations. From the ionisation energies of the O=S=O/HN=S=O pair a parameter απSN can be deduced, which proves to be useful in the discussion of other SN compounds like R3C-N=S=O and RN=S=NR.
Untersuchungen zur Charakterisierung des Prochamazulens Matrizin aus Matricaria chamomilla L.
(1982)
The relative configuration of the thermolabile chamazulene precursor matricine has been established by NMR spectrometric studies.
The NMR spectral data prove to be consistent with the well-known structure of the chamomile component. On the basis of our results the levorotatory natural substance moreover can be specified stereochemically as (−)-(3S*, 3aR*, 4S*, 9R*, 9aS*, 9bS*)-4-acetoxy-2,3,3a,4,5,9,9a,9b-octahydro-9-hydroxy-3,6,9-trimethylazuleno[4,5-b]furan-2-one.
The stereochemistry of the bisaboloids in chamomile-with the exception of bisabolol-oxide C-has been elucidated. The in-vitro-examination of the mutual convertibilities of some bisaboloids gave evidence for the stereochemical accordance of the common chiral centres of all the bisaboloids. The absolute configurations of the remaining third asymmetric carbon atoms in bisabololoxide A and B have been determined by NMR spectrometric studies in comparison with their unnatural semisynthetic epimers. All the stereogenic centres of the bisabololoxides A and B, of (-)-α-bisabolol and of bisabolonoxide A turn out to be S-configurated.
The reactions of diluted aqueous solutions of SO2 resp. HSO3-ions with MnO4-or Ce4+ ions in the pH range 1-4 produce chemiluminescence in the spectral region of 450-600 nm. Measurements of the time course of the light emission and their simulation on an analog computer led to a reaction scheme in which a recombination product of primarily formed HSO3 radicals -of a lifetime of about 1 second -appears as precursor of electronically excited SO2 molecules. The participation of singlet oxygen can be excluded because at least the reaction with Ce4+ ions proceeds also in the absence of oxygen.
Eight-membered rings of the composition [SO2(NR)2PR′]2 3a-d with R = CH3, C2H5, and R′ = CH3, C6H5, were prepared from substituted sulfamides and dichlorophosphanes in the presence of a tertiary amine. These molecules were characterized on the basis of 1H and 31P NMR investigations and of mass spectra. 3 a reacts with phosphorus pentachloride to yield the spirocyclic derivative 4 with the phosphorus atom in the center of two four-membered rings. Methyliodide reacts with 3 a and 3 b under opening of the eight- membered ring and formation of phosphonium salts. The structure of 3 b is discussed in detail. 8b crystallizes in the orthorhombic space group Pna 21 with a = 12.60(0), b = 13.27(1), c = 12.62(4) Å.
The thermal decomposition of 1,2-diadamantyldioxetane was studied by kinetic and spectroscopic methods. Spectra of the chemiluminescence emitted during the thermally induced decomposition of 1,2-diadamantyldioxetane, tetramethyldioxetane and trimethyldioxetane were obtained and the influence of quenchers and radical-scavengers, and the presence of "heavy atoms" in the surrounding of the emitting species was investigated. The kinetics of the decay mechanism was followed by measuring the time dependence of the chemiluminescence. The influence of radical-scavengers, quenchers and "external heavy atoms" on the kinetics was assessed. Experimental results were discussed in terms of a biradical decay mechanism.
Arsenhaltige Heterocyclen
(1978)
In the reaction of N,N'-bis-trimethylsilyl-dimethylurea with As[N(CH3)2]3 a four membered ring O = C(NCH3)2AsN(CH3)2 1 could be isolated. 1 was not obtained by cleavage of the Si-N-bonds with the corresponding chloride. In contrast CH3N[CONCH3Si(CH3)3]2 reacts with AsCb to yield the six-membered ring CH3N(CON-CH3)2ASCl 2. The four-membered ring which contains an arsenic-halogen bond seems to be unstable. In the adamantane-type compound, AS4(NCH3)6, one methylamine could be eliminated by CF3SO3H to give AS4(NCH3)5(OSO2CF3)2 3. 1H, 19F NMR as well as mass spectroscopy have been used in the characterization of the products obtained.
The title compound N,N-bis(trimethylstannyl)trifluoromethanesulfonamide (1) reacts with S2Cl2, SOCl2 and SO2Cl2 in a molar ratio 2:1 to yield the compounds S2Cl2 a twelve-membered ring 6. These are the largest neutral sulfur-nitrogen rings of coordination number two at the sulfur atoms known to date. 3 reacts with SOCI2 under migration of a methyl group from the tin to a sulfur atom to yield CF3SO2(R3Sn)NS(CH3)NSO2CF3 (7). 2,2,4,4-Tetramethyl-1,3-bis(trifluormethylsulfonyl)cyclodisilazan and 7 are formed by the reaction of 3 with R2SiCl2- The analogous four-membered germanium compound 8 is obtained from 1 and R2GeCl2. While the pyrolysis of 1 yields only the six-membered cyclotristannazan 9, the six-membered germanium analog is only formed in minor amounts. By treating 9 with R3SiCl the ring is decomposed to give 10. A six-membered ring is formed from the reaction of 1 with ClR2SiOSiR2Cl 11. The structure of 6 is discussed in detail. 6 crystallizes in the monoclinic space group C2/c with a = 24.408(5), b = 7.377(2), c = 16.715(3) Å, β = 117.16(3)° and Z = 4. It has a chair conformation which is different from the isoelectronic S12-structure.
The reactions of N,N′ -bis(pentafluorophenyl)sulfurdiimide with [(CH3)3Sn]2NCH3, [(CH3)3Sn]3N and [(CH3)3Sn]2NC6F5 yiels the 1:1 adducts 1-3. 1H and 19 F NMR investigations show, that fluorine atoms in the ortho position of the phenyl ring coordinate to the tin atom. This causes an increase of electron density at tin. A similar interpretation is given for the adduct 4 of N,N′-bis(p-chlorophenylsulfonyl)sulfurdiimide and [(CH3)3Sn]2NCH3, where an oxygen atom of the sulfonyl group is bonded to tin.
Über Reaktionen von 3-trifluormethylphenylsubstituierten silicium-und zinnorganischen Verbindungen
(1978)
Several routes were investigated for the preparation of 3-CF3C6H4N[Si(CH3)3]2 2 and 3-CF3C6H4N[Sn(CH3)3]2 3. The latter compound reacts with 3-CF3C6H4NCO to yield [3-CF3C6H4(CH3)3SnN]2CO 4. A substituted urea 5 is also formed from [(CH3)3Si]2NCH3 and 3-CF3C6H4NCO. 5 is used for the preparation of cyclic compounds, with S2Cl2 the ten-membered ring (3-CF3C6H4NCONCH3S2)2 6 is formed. 5 and HN(SO2Cl)2 yield the six-membered ring 3-CF3C6H4NCONCH3(SO2)2NH 7. SeOCl2 and 5 react under formation of a spiro compound (S-CF3C6H4NCONCH3)2Se 8. The compounds were characterized on the basis of mass and 19F NMR spectra.
As[N(CH3)2]3 reacts with the following isocyanates: FSO2NCO, n-C4F9SO2NCO, SO2(NCO)2 and (CH3)3SiNCO. The products which result from reaction of FSO2NCO and n-C4F9SO2NCO are the acyclic tri- and bisubstituted arsines [xxx]
In contrast, SO2(NCO)2 and (CH3)3SiNCO form eight- and four-membered ring compounds, where the skeleton consists of the atoms As2S2N4 (3) and As2N2 (4). The new compounds were characterized by NMR and mass spectra.
Über das Verhalten von silicium- und zinnorganischen Verbindungen bei der Synthese von Heterocyclen
(1977)
The isocyanates of silicon (CH3)2Si(NCO)2 and Si(NCO)4 react with CH3N[Sn(CH3)3]2 and N[Sn(CH3)3]3 to yield the cyclic derivatives 2a-2b as well as the spiro compound 3. The structures of the compounds are discussed on the basis of 1H NMR and IR data. Mass spectra are not conclusive for assigning a certain structure. SO2(NCO)2 and (CH3)3Si-S-Si(CH3)3 form a cyclic compound 4 which contains two sulfur atoms of coordination number two and four. The results of the mass spectra can be interpreted by assuming that a rearrangement occurred. 4 hydrolyses under formation of 5.
The kinetically stable triazatriphosphorinyl and tetraazatetra-phosphorocinyl azides 3 and 4 are prepared from the corresponding chlorides 1, 2 with sodium azide. 3 and 4 react with phosphanes to yield the λ5 -diphosphazenes 5a-d. By the reaction of 1 or 2 with KCN the nitriles 6 and 7 are formed. -The new compounds are characterized on the basis of IR and mass spectra.
N-Sulfonylsulfimide
(1978)
(CF3SO2NSO2)2 (1), a compound with a four-membered ring, was prepared from CF3SO2NSO and SO3. 1 as well as (FSO2NSO2)2 form 1:1 adducts with S4N4 , pyridine and pyridine carbonitrile-4 (2a-2f). By comparison with FSO2NCOS4N4 it was shown that a dipolar type of addition had occured. In contrast the reaction of 1 and (FSO2NSO2)2 with aromatic nitriles yields 1:2 cycloaddition products (3a-3g) which were characterized on the basis of mass spectra. The six-membered rings of 4a-4b which contain carbon, nitrogen and sulfur atoms were obtained from the reaction of isocyanates with (FSO2NSO2)2 or (CF3SO2NSO2)2. 4-BrC6H4NCO and SO3 react in a similar way to yield 5. The starting materials are extremely sensitive to moisture while most of the adducts can be handled in open air without decomposition.
Novel radical anions of trimethylstannyl substituted naphthalenes and their ESR spectra are reported. Both 119 Sn and 117 Sn coupling can be assigned unequivocally. The perturbation of π systems by R3X substituents of group IV b elements X = C, Si, Ge, Sn and Pb is discussed with respect to photoelectron ionization potentials, charge transfer excitations, half-wave reduction potentials and ESR spin distribution.