Band 39, Heft 10

A structural investigation on single crystals of SF 4 yielded the cubic space group Fm3m with a = 676.1(5) pm and Z = 4 and from this cubic close packing and at least sixfold disorder of isolated molecules. In one of the experiments of manipulating SF 4 unintentional hydrolysis of the compound in a Duran-glass vacuum line occurred. The products SiF 4 and SOF 2 could be characterized by structure analysis after a miniature zone-melting separation and crystal growth in one and the same thin-walled capillary. The results for SiF 4 [14̄3m, a = 547.6(1) pm, Z = 2 at -117 °C] confirm earlier work with a higher numerical accuracy. SOF 2 crystallizes in the monoclinic space group P2 1 /c with a = 524.7(1), b = 704.9(2), c = 1449.3(4) pm, β = 97.20(2)° at - 137 °C and Z = 8. Isolated molecules of pyramidal geometry are arranged in strongly folded layers with intermolecular S···O contacts.

The melting diagram of the system NOF-HF (HF-rich region) was studied by DTA and X-ray diffraction. The compounds NOF·3HF and NOF·4HF were confirmed as intermediate solid phases, and formation of a new one, NOF·7HF , was observed. The melting points are -1 °C (dec.), 5 °C and -106 °C (dec.), respectively. The crystal structures of NOF·3HF (space group R3c ,Z = 6 , a = 7.396 Å , c = 12.678 Å) and NOF·4HF (14 1 /a, Z = 4, a = 6.316 Å , c = 13.301 Å) were determined as those of nitrosonium hydrogen fluorides, NO[F(HF) 3 ] and NO[F(HF) 4 ], with orientational disorder of the cations and very strong F-H···F hydrogen bonds in the anions.

In the reaction of P 2 H 4 with n-BuLi the product pattern strongly depends on the stoichiometric ratio and the reaction temperature (-25 °C or -78 °C). The following polyphosphides have been detected by 31 P NMR spectroscopy: LiH 8 P 7 , LiH 4 P 7 , LiH 5 P 8 , Li 2 H 2 P 14 , LiH 2 P 7 , Li 2 HP 7 , Li 3 P 7 , LiH 4 P 5 , LiH 4 P 3 , LiH 3 P 2 , and a still unidentified compound Li x H y P z .

By the reaction of cyanogen with 2,2,2-trifluoroethanol in the presence of a base catalyst, bis(2,2,2-trifluoroethoxy)-1,2-diiminoethane (1) is obtained. 1 can be easily cyclized with halides to yield five-membered ring compounds. Triethylamine serves as an HCl-acceptor. The building elements of the rings are S 2, 3, Se 4, P 5 and As 6, respectively. 5 reacts with Mg to form the diphosphane 7.

The He I photoelectron spectra o f the group V trihydrides and trihalides are assigned on the basis of a qualitative D 3h /C 3v -MO model which includes the analogous group III trihalides. Trends and irregularities across the series by varying either the central atoms or the substituents are discussed. U sing experimentally fitted (PES) and optimized parametrization the new SCC -X α method yields results in excellent agreement with both measured ionisation potentials and dipole m om ents, especially for the heavier homologues. The electronic distribution and the trends in electronic and molecular properties are examined for the model series ER 3 (E=N→Sb; R=H,Cl) and AsR′ 3 (R′=H, Hal) within a complete SCC-X α (and EHT) population analysis. - The PE Spectrum of BiMe 3 is presented.

Polymeric phosphono-vanadates M I[ CH 3 PVO 5 ]·H 2 O (M=K, NH 4 ) and the acid H[CH 3 PVO 5 ]·H 2 O have been prepared. K[CH 3 PVO 5 ]·H 2 O crystallizes in the trigonal space group P3 1 21 with a = 1111.2(2) and c = 1004.0(3) pm, and consists of an open structure of corner sharing V-O- and CH 3 -P-O-polyhedra. Polyhedral chains form helices along the screw axis of the space group. The vanadium polyhedron can be described as highly distorted trigonal bipyramid with two terminal oxygen atoms.

A series of mononuclear complexes of ruthenium containing the cyclic triamine ligand 1,4,7-triazacyclononane ([9]aneN 3 = L; C 6 H 15 N 3 ) have been prepared: [Ru II L (dmso) 2 Cl]Cl (dmso = dimethyl sulfoxide), [Ru III LX 3 ] (X = C1 - , Br - ), [RuL 2 ](PF 6 ) 2 , [RuL(C 2 O 4 )I]. Hydrolyses of RuLCl 3 under a variety of reaction conditions afford dinuclear species: [Ru III 2 L 2 (μ-OH) 2 (μ-CH 3 CO 2 )]I 3 ·H 2 O , [Ru III 2 L 2 (μ-OH) 2 Cl 2 ](PF 6 ) 2 , and the mixed-valence species [Ru 2 L 2 (μ-Cl) 3 ](PF 6 ) 2 . The complex [Ru 2 L 2 (μ-OH) 2 (μ-CH 3 CO 2 )]I 3 -H 2 O has been characterized by a single-crystal X-ray diffraction study. The compound crystallizes in the monoclinic space group P2 1 /c with a = 14.70(1) Å , b = 19.00(1) Å , c = 9.714(7) Å , β = 99.62(7)°, and V = 2674 Å 3 , d calcd = 2.37 g cm -3 for Z = 4, and mol wt 952.3. The structure was solved by direct methods using 2519 unique reflections with I > 2σ(I). Final residuals were R 1 = 0.0615 and R 2 = 0.075. The structure consists of μ-hydroxo- and μ-acetato- bridged dinuclear cations and iodide anions. The observed diamagnetism and a short Ru-Ru bond distance of 2.572(3) Å are indicative of a Ru-Ru single bond. The electrochemical properties of [Ru 2 L 2 (μ-OH) 2 (μ-CH 3 CO 2 )] 3+ and [Ru 2 L 2 (μ-Cl) 3 ] 2+ have been investigated by cyclic voltammetry, and by coulometry. Two one-electron redox processes have been identified for both complexes the first of which exhibits a reversible wave, whereas the second wave at more negative potentials is irreversible. The blue mixed valence species [Ru 2 L 2 (μ-OH) 2 (μ-CH 3 CO 2 )] 2+ has been characterized in solution.

The molecular and crystal structures of the nor-heteroadam antanes CH 3 C(CH 2 As) 3 [C(COOCH 2 CH 3 ) 2 ] 2 (1) and CH 3 C(CH 2 As) 3 Se 2 (2) have been investigated in order to obtain confirmation of the rare structures deduced earlier from mass, 1 H NMR and vibrational spectroscopy. Crystals of 1 are triclinic, space group P1̄-C 1 i with a - 769.27(30), b = 1036.09(14), c = 1599.18(17) pm, α = 98.236(10)°, β = 97.987(18)°, γ = 103.633(20)° and Z = 2. On the basis of 1821 unique reflections the structure was refined to a weighted R value of 5.28%. The crystals of 2 are monoclinic, space group P 2 1 /c-C 5 2h with a = 1102.73(23), b - 727.49(14), c = 1281.27(42) pm. β = 98.803(21)° and Z = 4. On the basis of 1065 unique reflections the structure was refined to a weighted R value of 5.93%. Several attempts to synthesize CH 3 C(CH 2 As) 3 Te 2 failed.

The novel 5-exo-phosphino-η 4 -cyclopentadienyl complexes (η 4 -C 5 H 5 PR 1 R 2 )Fe(CO) 3 (4) (a: R 1 =R 2 =SiMe 3 ; b:R 1 =t-Bu; R 2 =SiMe 3 ) are obtained by the nucleophilic addition of LiPR 1 R 2 to the carbocyclic ligand in [(η 5 -C 5 H 5 )Fe(CO) 3 ]PF 6 . At room temperature 4a, b are converted into (η 5 -C 5 H 5 )(CO) 2 Fe-PR 1 R 2 (5a, b).

Preparation and properties of the title compound are described. It is present as a mixture of the isomers I and II. The 1 H, 13 C, 19 F, and 31 P NMR spectra are discussed in detail. For amino fluoro phosphoranes rules for the estimation of NMR chemical shifts and coupling constants are given.

The molecular structure of 3,5-dimethylbenzoic acid has been accurately determ ined by X-ray crystallography. The crystals are monoclinic, space group P2 1 /n, with a = 8.165(2), b = 6.992(1), c = 14.422(2) Å , β = 93.21(2)°, Z = 4. The structure has been refined by full-matrix least-squares techniques to R = 0.0415 on 1662 counter intensities. The carbon skeleton of the benzene ring has C 2v symmetry within experimental error. The six aromatic C-C bond distances do not differ significantly from each other; some of the internal ring angles, however, deviate from 120° by as much as 2°. After correction for systematic effects, such as the asphericities of the electron density distribution and the libration of the molecule in the crystal, the mean aromatic C-C bond distance is 1.401(1) Å , and the two independent C-CH 3 bond distances are 1.509 and 1.511(3) Å. These values are in outstanding agreement with the corresponding r g distances measured by gas electron diffraction in p-xylene (1.400±0.003 Å and 1.512±0.003 Å , respectively) and mesitylene (1.401 ±0.002 A and 1.509±0.002 Å, respectively). The deviations of the ring angles from 120° are interpreted fairly well as arising from the superposition of separate, independent angular distortions from each substituent.

In the system 1-sila-2,4-cyclohexadiene (l)/tert-butyllithium/trimethylchlorosilane the following reaction types have been observed: nucleophilic substitution, metallation, addition of tert-butyllithium to the diene fragment, addition of lithium hydride to the diene fragment, silicon-carbon bond cleavage, and transmetallation. The resulting products 2-11 have been characterised by their 1 H and 13 C NMR data; the compounds 2, 3, 6, 8 and 10 could be isolated in a pure form. The relative quantities obtained of the compounds 2-11 depend on the reaction conditions (solvent, temperature, order of addition).

Phenylenedioxydiacetamides are examples of noncyclic ionophors that are able to form 2:1 complexes with the cations Ca 2+ and K + in acetone, methylene chloride or acetonitrile solution. The chelation abilities and coordination modes of 12 derivatives were investigated systematically by IR, 1 H NMR and 13 C NMR spectroscopy. The results indicate that only the 1,2-phenylenedioxydiacetam ides function as ligands; while the 1,3-derivatives do not coordinate. The ionophors 1-8 act as tetradentate chelating ligands with all four oxygen atoms involved in bonding to the cation. Irrespective of its charge, each cation is coordinated by two ionophors.

The synthesis of formaldehyde complexes (OC) 2 L 2 FeCH 2 O(L=P(OEt) 3 (2b), L = P(OiPr) 3 (2c)) and CpRe(CO) 2 CH 2 O (3) is reported. A(OC) 2 [P(OMe) 3 ] 2 FeCH 2 O compound (2a) reacts with CO,PPh 3 and C 2 H 4 substituting the CH 2 O ligand. CH 3 I and H 2 also cause elimination of formaldehyde with oxidative addition to the Fe(CO) 2 [P(OMe) 3 ] 2 fragment. HI adds to 2c to give a iodomethyl complex 5, which has been characterized by an X-ray structure determination.

The preparation of cyclo-(CF 3 CN)(NSCl) 2 (2) from CF 3 CN and (NSCl) 3 is reported. Dechlorination of 2 by Zn in liquid SO 2 is found to yield either CF 3 CN 3 S 2 or mainly CF 3 CN 2 S 2 , depending on the reaction conditions. The structure of 2 was determined from single crystal data.

Pyrryl-heptadecyl-carbinol and Pyrryl-9-anthracenyl-carbinol are cyclised in acidic medium to the corresponding meso-tetra-substituted porphyrins. The meso-tetra-substituted porphyrins are transfered to the iron complexes.

9-Trifloxyacridinium salts 3a, b and 9,9′-oxy-bis(acridinium ) salts 4a, b which are easily obtained from the 9-acridones 2 a, b react readily with halides, pseudohalides and sulfur nucleophiles to give 9-substituted acridinium ions. This reaction represents an efficient alternative to the commonly used transformation of 9-chloroacridinium into other substituted acridinium salts; the two-step conversion of the carbonyl com pound into a (pseudo)halide-substituted carbenium ion or into a thione may be generally applicable to ketones which can be transformed either into trifloxy carbenium ions or into dication ethers.

The photochemical reaction between 1,4-naphthalenedicarbonitrile (NDN) and toluene in acetonitrile is extended to bibenzyl (4), 3- and 4-fluorotoluene (8, 7), and 3- and 4-m ethoxytoluene (9, 10). The product distribution obtained with com pounds 4, 7 and 10 is similar and includes 4-benzyl-1-naphthalencarbonitriles (1a -c), 1-benzyl-1,2-dihydro-1,4-naphthalenedicarbonitriles (5a-c), cis 2-benzyl-1,2-dihydro-1,4-naphthalenedicarbonitriles (2a-c) (with com pound 10 also the trans isomer 12), 12-substituted 6,11-dicyano-5,11-methano-5,6,11, 12-tetrahydrodibenzo[ a,e]cyclooctenes (3a, b) (not obtained with com pound 10), besides the hydrocarbons arising from the coupling o f the respective benzyl radicals (products 6a-c). With com pound 9 the only process observed is reduction of NDN to 1,2-dihydronaphthalene-1,4-dicarbonitrile (11). The results obtained fit into the previously proposed mechanistic scheme, involving electron and proton transfer follow ed either by in cage radical coupling to form products 2, 3, 5 and 12 or radical escape leading to products 1 and 6. The effect of substituents on the various phases of the reaction is discussed.

Diarylthallium hydroxides react very smoothly in organic solvents with hydroquinones to stable paramagnetic complexes. This reaction has been investigated with two ligands and several organometallic compounds in 8 different solvents. In basic solutions clearly two paramagnetic species can be detected by ESR spectroscopy. One component exhibits a large doublet splitting assigned to the thallium counterion and the second radical does not show any metal coupling. The relative concentrations of both radicals depend strongly on the solvent and the temperature. Therefore, a slow equilibrium betw een a contact ion pair and a solvent separated ion pair is assumed. The thermodynamic parameters are determined to ⊿H = 0.8 kcal/mol, ⊿G 293 = -0.1 kcal/mol, ⊿S = 3.04 cl/mol. The proton and thallium coupling constants as well as the g-value of the contact ion pair show a rem arkable temperature dependence. The signs of proton splitting constants are determined by ENDOR-TRIPLE investigations. The change of the electronic structure of the radical anion by formation of a contact ion pair is discussed. For interpretation of these results we assumed a fast equilibrium between different conformations of the contact ion pair according to behaviour of comparable aroxyl radicals. Therefore, the systems investigated allow a simultaneous observation of solvent separated and different contact ion pairs.

Tetratriacontanyl palmitate, tetratriacontanyl nonadecanoate and 2″-O-glycoside of 5-acetonyl- 7-hydroxy-6-glucosyl-2-methyl chromone have been isolated from the seeds of Cassia spectablis.

Chlorination of the di-tert-butylation product of 2-naphthol leads to 3,6-di-tert-butyl-1,1-dichloro- l,2-dihydronaphthalen-2-one (4a) instead of 1,6-di-tert-butyl-1,3-dichloro-1,2-dihydronaphthalen-2-one (2) as reported [2], The structural proof was mainly offered by 13 C NMR spectroscopy. The influence of annelation and chlorine substitution in 1,2-dihydronaphthalen-2-ones on δ 13c=o is discussed, which is of importance for the use of δ 13c=o for a general discrimination between ortho- and para-quinolide structures.

The role of singlet oxygen ( 1 O 2 ) in the photo-oxidation of the furocoumarin im peratorine was investigated in vitro. Irradiation with visible light and sensitization with methylene blue yielded the imperatorine oxidation product isogosferol and the corresponding ketone as main products. The involvement of 1 O 2 was dem onstrated by studying the rate of oxidation under conditions that affect the lifetime of 1 O 2 . Com pared to a range of other furocoumarins, im peratorine appeared to be moderately active as a 1 O 2 generator. The extent of 1 O 2 production correlated with the skin sensitizing activity. Upon irradiation of im peratorine itself with UVA light (360 nm) no isogosferol formation is observed, probably as a consequence of its photochemical instability. Irradiation with visible light (λ > 400 nm) of a chlorophyll chromophore containing sensitizer in the presence of imperatorine, yielded isogosferol and the corresponding ketone product. This dem onstrates that in the formation of 1 O 2 oxidation products of imperatorine in plants naturally occuring sensitizers e.g. chlorophyll and visible light are involved, rather than 1 O 2 produced by im peratorine or other furocoumarins and UVA light. The protective effect on the chlorophyll sensitized im peratorine oxidation by the 1 O 2 - and chlorophyll triplet quencher β-carotene was demonstrated in a lipophilic solvent.

Regiochemistry and site specifity of [4+2] cycloaddition reactions of 4,4-bis(trifluoromethyl)-1,3-diazabuta-1,3-dienes with enolethers, enamines and heterocumulenes are described. IR, 1 H , 13 C, and 19 F NMR data of the compounds obtained are discussed.