Volume 33, Issue 3

Molecular orbital calculations for [C 7 H 7 Fe(CO) 3 ]-predict a η 3 -allyl anion Fe(CO) 3 complex with un-coordinated diene part of the C 7 H 7 ligand to be more stable than the alter-native η 4 -butadiene Fe(CO) 3 form, the cyclopolyenyl ligand being nonplanar in either case. The tiny energy difference between both coordination modes accounts for the observed high fluxionality of the anion.

The crystal structure of the [C 7 H 7 Fe(CO) 3 ] - anion stabilized with the [(C 6 H 5 ) 4 As] + cation has been determinated by X-ray diffraction. The crystals are monoclinic, space group P2 1 /n. The unit cell with lattice constants a = 1607.9 pm, b = 1386.8 pm, c = 1249.1 pm and β - 91.52° includes four formula units. The Fe(CO) 3 group is bonded to the allyl anion part of the C 7 H 7 ring system, while the diene part is unco-ordinated.

cis-Dioxo-dipicolinato-vanadate(V), Crystal Structure, IR, Raman The crystal structure of Cs[V(O) 2 (dipic)]·H 2 O (dipic = pyridine-2,6-dicarboxylate) has been determined by single crystal x-ray diffraction analysis. The compound crystallizes in the monoclinic space group P2 1 /a, with cell constants a =737.8(3), 6=1917.5(5), c = 792.9(3) pm, β= 94.87(6)°, and Z = 4. The geometry about vanadium is a distorted trigonal bipyramid containing a cis-dioxo moiety (∢ O-V-O 109.9(3)°, V=O bond lengths 161.0(6) and 161.5(6) pm). Vibrational absorptions ν s (V - 0) and ν as (V=O) were found at 956 and 947 cm -1 in the IR and Raman spectrum, resp.

The structures of two modifications of CuZrF 6 by means of neutron diffraction on powder samples in the temperature range from 298-560 K are reported. All modifications consist of octahedra, which share corners in three dimensions and which are centered alternately by Cu 2+ or Zr 4+ . The high temperature α-modification crystallizes in space group Fm3 (No. 202) with α = 7.939 Å. There is experimental evidence, that the CuFe-octahedra are distorted by a static Jahn-Teller-effect. The space group P1̄ (No. 2) with Z = 2 is proposed for the low-temperature γ-modification.

The crystal structures of Na 9 Sn 4 and Na 15 Sn 4 have been determined. Na 9 Sn 4 crystallizes orthorhombic, a=542 ±1, b = 939 ±2, c = 2962 ± 6 pm, isotypic with LigGe 4 . Na 15 Sn 4 crystallizes cubic, a = 1314 ± 2 pm, isotypic with Na 15 Pb 4 (Cu 15 Si 4 -type). The structural relationship of Na 9 Sn 4 to the variants of the W-Structure type is shown.

Redox properties of layer type chalcogenides of main group V elements were investigated in molten salt and organic Li + -electrolytes. Even at room temperature, Bi 2 S 3 , Bi 2 Se 3 and Bi 2 Te 3 can be reduced with about 100% material efficiency to Li 3 Bi as final product. The reduction of Bi 2 S 3 to Bi 0 and Li 2 S can be reversed in organic electrolytes.

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 α π SN can be deduced, which proves to be useful in the discussion of other SN compounds like R 3 C-N=S=O and RN=S=NR.

Mandelic Acid, Osmium(VIII) In the reaction between mandelic acid and Os(VTII), the rate of Os(VIII) disappearance was found to be proportional to the concentration of mandelate ion and Os(VIII). At low and high hydroxyl ion concentration the rate shows second and zero order dependence respectively. The reaction was studied at different temperatures and various activation parameters ⊿E, PZ, ⊿S* etc. were evaluated.

The reactions of diluted aqueous solutions of SO 2 resp. HSO 3 -ions with MnO 4 -or Ce 4+ 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 HSO 3 radicals -of a lifetime of about 1 second -appears as precursor of electronically excited SO 2 molecules. The participation of singlet oxygen can be excluded because at least the reaction with Ce 4+ ions proceeds also in the absence of oxygen.

(NSOF) 2 (CH 3 NSO 2 ) 2a reacts with methanol to give sulfuric acid, aminosulfuric acid and SO 2 (NHCH 3 ) 2 as final products. The primary reaction was studied by 1 H and 19 F NMR spectroscopy. A 1:1 adduct 2a · CH 3 OH (=3) and a monosubstituted product which has the formula (NSOF)(NSOOCH 3 )(CH 3 NSO 2 ) 4 were detected to be intermediates. As 2 a is chiral, the reaction with racemic butanol-2 proceeds via diastereomeric inter-mediates which were identified by their 19 F NMR spectrum. The reaction pattern of 2a is explained.

Several spin-labeled oxyphosphoranes have been prepared by oxydative addition of biacetyl and hexafluoroacetone to phosphites containing the 4-oxy-1-oxyl-2,2,6,6-tetra-methylpiperidine group. The new compounds have been characterised by ESR and 31 P NMR spectroscopy as well as by mass spectra.

The reaction of PH 3 , MePH 2 , and Me 2 PH with hexafluoroacetone was re-investigated. The already reported compounds H 2 PC(CF 3 ) 2 OH and Me(H)PC(CF 3 ) 2 OH as well as the two other products HP[C(CF 3 ) 2 OH] 2 and MeP[C(CF 3 ) 2 OH] 2 were formed. No Me 2 PC-(CF 3 ) 2 OH could be isolated from the reaction of Me 2 PH and hexafluoroacetone, however. Me 2 PPMe 2 , Me2P(O)OCH(CF 3 ) 2 and the phosphorane Me 2 PF[OCH(CF 3 ) 2 ] 2 which exhibits non-rigidity at room temperature according to the 1 H and 19 F NMR spectra, were obtained. For all compounds IR, NMR, and MS data are given.

A final decision between the 2-and 3-oxide structure of the thermally or photo-chemically accessible monoxides of 1,2,3-thiadiazoles is given with the aid of an X-ray analysis of 4-phenyl-1,2,3-thiadiazole-3-oxide. The compound crystallizes in the ortho-rhombic space group Pbca, Z = 8, with a = 7.598(6), b= 18.865(5) and c= 11.225(6) Å. The structure was solved by the heavy atom method and refined to R = 0.042 for 1643 independent reflections. The heterocyclic ring is planar within experimental error and the bond distances S-C and S-N are rather short. In the crystal the molecules are linked by an unusual short contact distance between sulphur and oxygen (2.75 Å).

Using the pulse radiolysis technique the OH adducts of cytosine, 5-methyl cytosine and 2'-deoxycytidine were investigated in alkaline N 2 O saturated aqueous solutions. Ab-sorption spectra were recorded and their change with time was correlated with the change in conductivity. An OH -induced reaction (1.4·10 8 )·mol -1 ·s -1 ) was observed with OH adducts of cytosine and 5-methyl cytosine leading to radicals (pK=10.3), the G-values of which were 3.2 and 1.6 respectively (conductivity measurements). These intermediates were assigned to the C-5 OH radical adducts. After completion of the free radical reactions (2k = 6 · 10 8 )·mol -1 ·s -1 ) the resulting product mixture showed pK-values of 8.3 (cytosine, G=0.6), 10.5 (5-methyl cytosine, G=0.8), 10.7 (cytosine, G=1.5; 2′-deoxycytidine, G=1.5) and 12.4 (cytosine, no G-value, determinable with optical detection). Ammonia, which is a product measured after γ-radiolysis of all the three compounds investigated (G(NH 3 ) = 0.6 ± 0.1), is not released within 15 ms after the pulse.

Oxygenated 1M aqueous solutions of 2-methyltetrahydrofuran (MTHF) or D-glucose were γ-irradiated, and G(total peroxide) was determined as a function of dose rate and temperature. Whereas MTHF was oxidized by a chain process, D-glucose was not. The peroxyl radicals derived from D-glucose rapidly eliminate HO 2 ·. At natural pH HO 2 ·(pK=4.75) is largely deprotonated. O2- does not propagate a chain.

Using bisisochinolin derivatives and related compounds it is shown that information about the fluorescent state can be obtained by comparison of experimental fluorescence data and calculated energies of the Si-state assuming various geometries.

2-Chloro-5-methoxy-p-benzoquinone [1] reacts with zinc mercaptide [2] to give 2-tri-fluoromethyl-8-methoxy phenothiazin-7-one (1), which on reduction with sodium di-thionite provided 2-trifluoromethyl-8-methoxy phenothiazin-7-ol. Synthesis of various acylated and alkylated derivatives (3 to 6) and their sulphoxides (7 to 8) have been described (Scheme 1).

Triphenylphosphinimine and cadmium iodide form a complex containing the dimeric molecule [CdI 2 HN:PPh 3 ] 2 . These dimers are centrosymmetric, with an eight membered ring containing the hydrogen bonded system N-H···I.

Two tri- and tetraseleninato complexes of tin, RSn(O 2 SeR) 3 (1) and Sn(O 2 SeR) 4 (2) (R =C 6 H 5 ), are obtained from trichlorophenyltin and tetra-chlorotin ,resp. with sodium benzeneseleninate. On the basis of the IR and Raman spectra 1 and 2 probably are polymeric mixed seleninato-O,O′-seleninato-O complexes (c.n. = 6).

By Potentiometrie titration the dissociation constants of 3-alkyl-2-benzofurancarboxylic and 2-alkyl-5-methyl-3-furancarboxylic acids are determined. It has been established that the acids of the acids of the benzofuran series are stronger than those of the furan series. The difference of the acidity of the compounds in each series is in accordance with the generally employed conception on inductive and mesomeric effects of the substituents.

Bentonite is used as an heterogenous catalyst in the liquid-phase alkylation of benzene and toluene.

Prosopis juliflora, Piperidine Alkaloids The isolation of three new alkaloids from Prosopis julifiora is reported. A structure for the minor alkaloid julifloridine is suggested.

The potential ⊿ 8 -tetrahydrocannabinol meta-bolites (6a, b) were synthesized starting from (+)-trans-p-menthadien-(2,8)ol(1) (2) and the resorcyl-alkyl esters (3a, b).

Mn(CO) 5 Br and (Me 3 Si) 3 P react to give Mn 2 (CO) 8 (μBr) (μP(SiMe 3 ) 2 ) 3. Using methanol, both Si-P bonds of 3 can be cleaved, forming Mn 2 (CO) 8 (μBr) (μPH 2 ) 4. On dissolving 4 in CCl 4 a P-H, C-Cl̲ exchange reaction is observed, yielding Mn 2 (CO) 8 (μBr) (μPCl 2 ). IR and NMR data are reported.

Using a newly developed technique that employs highly deuterated compounds and 2 H broadband decoupling the 13 C, 1 H spin-spin coupling constants for naphthalene have been measured from the 13 C NMR spectra of α-and β-H-[D 7 ]naphthalene. A linear dependence of the 3 J( 13 C, 1 H) data on the central π-bond order is indicated.