Volume 31, Issue 2

The 187 Re–NQR transitions of TlReO 4 and their temperature dependencies were measured. In the temperature range, in which TlReO 4 is crystallizing in pseudo scheelite structure, one obtains normal temperature coefficients with asymmetry parameters η = 0.3. For Τ < 200 Κ, however, another modification with η = 0 was found. For LiReO 4 • 2 H 2 O complex 187 Re and 185 Re NQR spectra with 16 transition frequencies were measured and discussed.

Re-NQR spectra of polycrystalline (H 3 C) 3 SiReO 4 and (H 3 C) 3 GeReO 4 show a strong temperature dependence of their transition frequencies, with temperature coefficients, which differ from those of the ionic perrhenates.

Compounds of the type R 1 -CH 2 -R 2 , where R 1 and R 2 represent phosphonyl, carbonyl and sulfonyl groups have been investigated by 13 C NMR. Chemical shifts and coupling constants of carbon to phosphorus or fluorine are discussed.

The structure of the high pressure compounds ZnAs and CdAs have been determined using Guinier film and counter methods. The compounds are orthorhombic, (space group Pbca; Z = 8), with α = 5.679(2) Å, b = 7.277(4) Å, c = 7.559(4) Å and α = 5.993(4) Å, b = 7.819(6) Å, c = 8.011(6) Å respectively. ZnAs and CdAs are isostructural with the normal pressure phases ZnSb and CdSb, which are related to the high pressure phase Si III. Structural relationships are discussed including the Si III-diamond structure relationship.

The densities of liquid mixtures in the systems AgCl-Ag 2 S, AgCl-Ag 2 Se, AgCl-Ag 2 Te, AgBr—Ag 2 Te, AgJ–Ag 2 Te and AgJ–Ag 2 S have been determined as a function of composition and temperature by a dilatometric method. The molvoluminaisotherms of the systems AgJ—Ag 2 S and AgJ–Ag 2 Te show negative deviations from ideality, the other systems behave ideally.

All three compounds of the type Fe[M B (CN) 6 ] (M B = Co, Rh and Ir) crystallize in the face-centered cubic system: space group Fm3m (Oh 5 ), Z = 4. The lattice constants increase in the order Fe[Co(CN) 6 ] (10.16 ± 0.01 A) < Fe[Rh(CN) 6 ] (10.42 ± 0.01 A) < Fe[Ir(CN)6] (10.43 ± 0.01 A). The infrared spectra showed four absorption bands which are assigned to the normal vibrations: V CN -, V M B_ C ', υM B -CN an d υ Fe-N• The observation of Fe-N stretching bands substantiates the existence of chemical bonding between iron and nitrogen atoms of the cyanide ligands. The intensive absorption bands around 26,5 kK are assignable to the charge transfer between Fe(III) and [M B (CN)6] 3 - groups, while the absorption bands in the UV region are assigned to the ligand field transitions of the [M B (CN)6] 3 ~ moiety. The Mössbauer spectra gave a single absorption line with a relatively small isomer shift, which is explained in terms of the formation of σ-bonding between Fe-N.

The reaction between dimethyl chloroacetylenephosphonate and tetramethyl acetylenediphosphonate with phosphanes is described. The starting materials and the reaction products are characterized by their NMR and IR spectra.

The electrolysis of isobutyraldehyde in the presence of water in alkaline methanol leads to α-hydroxy-isobutyraldehyde-dimethylacetal (1). The reaction probably occurs via the oxidation of the base conjugate to isobutyraldehyde to the carbenium ion and the subsequent nucleophilic addition of hydroxyl ion present in the electrolyte.

The He I photoelectron spectra of certain MeEHal 2 and Me 2 EHal compounds (E = (N), P, As, Sb; Hal = (F), Cl, Br, J; Me = CH 3 ) are interpreted in terms of a “composite molecule” approach derived for C 3v C s systems. Although an “internal standard” is missing here, substituent group-orbitals (n Hal , C—H) may be classified with respect to their orientations in space (R, V, T). Ionisation energies are assigned according to this assumption. PE data of the isoelectronic EMe 3 /EHal 3 compounds and of related molecules (Me 2 EH, MePH 2 , CF 3 PBr 2 ) as well as EHMO calculations with partial inclusion of spin orbit coupling are used to confirm the assignments given for Me 2 EHal/MeEHal 2 series. Correlations between PE ionisation energies (e.g. n E (IE)) and molecular or atomic properties are critically revised and discussed.

The reaction of tris-[dimethylamino]-arsine As(NMe 2 ) 3 with arsinous acid diolesters HO—RO—AsMe 2 leads to the formation of the arsolanes RO 2 AsY (Y = NMe 2 , OROAsMe 2 ) and the arsines Me 2 AsX (X = NMe 2 , OROAsMe 2 ). The reaction mechanism is discussed; IR and 1 H NMR spectral data are presented.

Pt(NH 3 ) 2 (SCN) 2 dissolved in liquid SO 2 reacts with molecular iodine to yield a green lustrous solid of stoichiometry Pt(NH 3 ) 2 (SCN) 2 I. The compound is diamagnetic in the solid state and in solution and has to be taken for a platinum(II, IV) mixed valence compound, therefore. Chemical and physical evidence so far suggest a linear chain solid with either iodide-bridged metal complex chains or metal complex stacks with parallel triiodide chains.

A series of transition metal complexes with the ligands L-Tyr, Gly-L-Tyr and Gly-L-Phe has been prepared. The magnetic moments, the IR and EPR spectra of the isolated compounds have been collected.

2,5-Dimethyl-3,4-diethyl-1,2,5-thiadiborolene (1) and Ni(CO) 4 yield yellow 1 • Ni(CO) 2 , which is converted to the corresponding bis( 1,2,5-thiadiborolene)-nickel(0), the first thermostable thioborane nickel complex. Spectroscopic data indicate a pentahapto sandwich compound with the electron-donating groups in approximately tetrahedral arrangement. This is confirmed by X-ray structural analysis. The title compound crystallizes in the space group p2 1 /c with α = 19.594(2), b = 11.8593(4), c = 9.3736(3) Å, β = 102.848(6)° and four molecules per unit cell.

A series of complexes formed between metal ions and the stable free radicals 3-carboxy-2,2,5,5-tetramethylpyrroline-1-oxyl, 3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl and glyoxal-bis(2,2,6,6-tetramethyl-4-iminopiperidine-1-oxyl) has been prepared. The magnetic moments and the EPR spectra of the complexes and the free ligands have been investigated. Some of the complexes show a temperature dependent interaction between the radicalic groups of the ligands.

The reaction of 1-phenyl-3-alkyl-triazenes with lewis acids in benzene has been examined in order to evaluate the mechanism of the reaction of alkyl azides with electrophiles in benzene. Evolution of nitrogen gives rise to the formation of the corresponding substituted anilines by intramolecular alkylation. Alkyl benzenes are the result of an intermolecular alkylation process.

Azidodiazonium tetrafluoroborates are readily accessible by a general reaction sequence. Nitrosation of the corresponding azidoarylamines with nitrosonium tetrafluoroborate or with alkylnitrites/tetrafluoroboric acid affords crystallinic salts, which were characterized by analytical and spectroscopic methods.

In the γ-radiolysis of deoxygenated N 2 O-saturated aqueous solutions of thymidine (10 -3 M, room temperature, dose rate 4· 10 18 eV/g.h., dose 6.7 10 17 -3.3 • 10 18 eV/g) the following products (G-values in parentheses) have been identified : 2,5-dideoxy-pentos-4-ulose (1) (0.01), 2,4-dideoxy-pentodialdose (2) (0.02), 2,4-dideoxy-pentos-3-ulose (3) (0.03), 2,3-dideoxy-pentos-4-ulose (4) (0.01), 2-deoxy-pentos-4-ulose (5) (0.1), 2-deoxyribonic acid (6) (0.02) and thymine (8) ( ≤ 0.2). In the presence of oxygen (N 2 O/O 2 80/20 v/v saturated) products 1-4 are absent, G (5) = 0.2, G (6) = 0.07 and G (8) ≤ 0.4. Furthermore, 2-deoxy-tetrodialdose (7) which is absent in deoxygenated solution is formed with a G-value of 0.03. Mechanisms are proposed to account for the scission of the N-glycosidic linkage. Product 6 is thought to be due to a primary OH radical attack at C-1′ of the sugar moiety, 8 arises from an attack at C-3′, 1, 4 and 5 from an attack at C-4′, and 2 and 7 from an attack at C-5′.

Starting with ( 14 C)chloroform 1,2,3,3-tetrachloro-(1,3- 14 C)-1-propene (7 z) with unsymmetrical distribution of 14 C is synthesized according reaction scheme 1. 7 z is isomerized with AlCl 3 to 1,2,3,3-tetrachloro-(1,3- 14 C)-1-propene (7 t) with symmetrical distribution of 14 C. From 7 z and 7 t the dichloro-( 14 C)acetanilides (13 z) and (13 t) are formed via the dichloro-( 14 C) acetic acids. The distribution of 14 C on C-1 (75%) and C-3 (25%) from 7 z follows from comparison of the activities of 13 z, 13 t with 7 z.

The kinetic of the chlorine exchange between ( 36 Cl)antimony(III)-chloride and hexachloropropene is studied in homogenous methylene chloride solution on variation of time, concentrations of ( 36 Cl)SbCl 3 , C 3 Cl 6 and temperature. A mechanism is given with a transition state with 4 molecules of SbCl 3 und 1 molecule of C 3 Cl 6

Nuclear magnetic line widths data have been used to determine the rate of solvent exchange between the coordination sphere of Fe(III)-protoporphyrin(IX)dimethylester or Fe(III)-tetraphenylporphyrin and the bulk phase of 1-methylimidazol/chloroform. At temperatures below 322 K both porphyrins are in the low-spin state and separate PMR absorption caused by the methyl protons of two 1-methylimidazol molecules complexed in fifth and sixth position of ferri-porphyrins is detected. At T ≳ 320 K an accelerated exchange of these ligands was observed and the underlying kinetic parameters have been extracted. It was found that this exchange takes place when the paramagnetic species is in its low-spin state. For 240 K ≲ T ≲ 290 K dynamic line broadening of bulk phase 1-methylimidazol indicates occurrence of chemical exchange attributed to 1-methylimidazol interacting with ferri-porphyrin in addition to the strongly bound axial ligands.

The reactions of 2-dimethylamino-3-methyl-[1,3,2]oxazarsolane with acid molecules HXR, H 2 X, HNR 2 and H 2 NR (X = O, S; R = alkyl-group) are examined. IR, NMR and mass spectral data of the obtained arsolanes are discussed. The molecular weight determinations and the mass spectra with chemical ionization show an assoziation by As–N–Asor As–X–As-bridges.

2-Aminothiazole-3-oxides react with esters of acetylenedicarboxylic acid to give fluorescent thiazolo-[3,2-a]-pyrimidones. In some cases intermediate rearrangement products can be isolated.

2-Acetylbenzimidazole condensed with aldehydes to afford the 2-cinnamoyl derivatives (1 a-e). Whereas 2-acetyl- and 2-benzoylbenzimidazole added Grignard reagents at the carbonyl group, the 2-cinnamoyl derivatives (1a, b) suffered addition at the olefinic double bond to give 2a, b. Condensation of amines with 2-acetyl and 2-benzoylbenzimidazole yielded the imino compounds (4a-c). 1 a reacted with thiourea to furnish the pyrimidine (5).

Mass-spectrometric investigations of the titel compounds show for the first time that SO-elimination is also possible from acyclic sulfonyl derivatives. From results of the defocusing technique follows that both this process and the elimination of CO 2 from the molecular ions are relative slow. Prove of these reactions can be found in the analysis of the metastable ions. These results are supported by substituent effects.

The proton magnetic resonance spectra of a number of substituted 2-acylamino-3-arylamino-1,4-naphthoquinones have been measured and discussed. The effect of various substitution pattern and hetero atoms on the chemical shift values of N-acylmethyl protons have been studied and explained.

The reaction of catharanthine under modified prevost reaction conditions has afforded 20-acetoxydihydrocatharanthine, an important intermediate for the synthesis of antileukaemic alkaloids, vinblastine and vincristine.

The Cascarosides A, B, C and D, for the first time isolated by FAIRBAIRN et al. from the bark of Rhamnus purshianus DC, have been structurally elucidated as 8-O-β-D-glucopyranosides of aloin and 11-desoxy-aloin respectively by means of partial hydrolysis, NMR spectroscopy, sugar analysis and DC measurements.

UV irradiation of [Me 4 N][VCp(CO) 3 ] and [Me 4 N]CN results in the formation of a complex with zero-valent vanadium which possibly has to be formulated as [Me 4 N] 4 [CpV(CO) 2 CN]2. A new method of preparation of K[CpV(CO) 3 CN] is described; 51 V NMR results and a complete IR spectrum are presented and discussed.

Two quenchable high pressure modifications of Dy YbS 3 are isotypic with U 2 S 3 and Ce 2 S 3 (Defect-Th 3 P 4 type).

A kinetic study was made of the primary step of the alkylation of benzene with propylene and ferric chloride as catalyst under homogeneous reaction conditions at several pressures up to 2 kbar. Initial reaction rate of cumene formation shows a minimum in the medium pressure range, thus indicating that product formation occurs via two different reaction paths with opposite pressure dependence.

The constitution and conformation of the known cyclopeptide alkaloid mauritine-A were determined by X-ray diffraction methods. All amino acids belong to the L-series, 3-hydroxy proline has trans-configuration. As indicated by the UV-spectrum, the 14-membered ring system is considerably strained.

Trimethylchlorosilane reacts with magnesium in hexamethylphosphortriamide yielding hexamethyldisilane. An organosilylmagnesium compound is proposed as reactive intermediate in this reaction. Further evidence for the existence of trimethylsilylmagnesium compounds could be obtained in the reaction of trimethylchlorosilane with highly reactive magnesium in tetrahydrofurane as solvent.

From the essential oil of Pimpinella anisum fruits a hitherto unknown type of phenylpropane was isolated. The mass, infrared, and 13 C NMR spectra indicate, that the unknown is a 2-methyl-butyric acid ester of 2-hydroxy-5-methoxy-trans-propenylbenzene.

Electrical conductivity of thiantrene monocrystals was observed. The experimental results were interpreted as a “hopping” mechanism between the molecules of crystal.

The reduction of imides with sodium borohydride affords ring cleaved products instead of the corresponding carbinol lactams suggested previously.