Volume 32, Issue 7

Propynal (2 a) reacts with water at temperatures of about —18 °C to give a single crystallized hydrate 1 a with the structure [xxx]. It decomposes at higher temperature into 2 a and water. No other hydrates of 2 a could be found. An analogous compound lb is obtained with H 2 S at about the same temperature. At room temperature it decomposes into H 2 S and 2 a, at higher temperatures into 3,3'-thiodiacroleine (6 a).

Malonaldehyde (2 a) is possibly an intermediate in the reaction of propynal (1) with itself, which ends up in 3-ethinyl-2,4-diformyl-pentanedial (6 a), a compound containing two malonaldehyde groups bridged by a substituted methylene group. The alkali salts of the unstable 1-thiomalonaldehyde (7 a) are obtained from 3,3′-thiodiacroleine (8 a) or S-acroleinyl-diphenylthiourea (8 b) and alkalisulfide or ammonia. 2-Chloro, 2-bromo- and 2-iodo-malonaldehyde (14 a-c) are prepared from 1 via 2,3-dihalogenpropenals (12).

AgAuCl 4 crystallizes in the monoclinic space group I2/c with Zi = 4. The crystal structure is built up by Ag + cations and square planar AuCl 4⁻ anions with Au-Cl bond length of 228 pm. The Ag + ions have an octahedral coordination of Cl atoms. AgAuCl 4 is topologically related to RbAuCl 4 .

The title compounds have been prepared and structurally characterized. Na 2 CuP crystallizes in the Na 2 CuAs-structure type/(Cmcm) forming infinite Cu—P-zigzag-chains. In the silver compounds we found analogous Ag—E(V)-chains in a cell with atomic positions, which slightly violate the above symmetry.

The phases LiFe 6 Ge 5 and LiFe 6 Ge 4 have been prepared and structurally characterized. They crystallize monoclinic (LiFe 6 Ge 5 : a = 8.74 4 Å, b = 5.04 5 Å, c = 14.84 1 Å, β = 101.42°; LiFe 6 Ge 4 : a = 8.73 9 Å, b = 5.04 5 Å, c = 7.17 0 Å, β = 113.94°; space group C 2/m), their structures show close relations to the structure of LiFe 6 Ge 6 and binary iron-germanium-phases.

As confirmed by X-ray data, the four ternary compounds CaZn 2 P 2 , CaCd 2 P 2 , CaZn 2 As 2 , and CaCd 2 As 2 crystallize trigonally in a CaAl 2 Si 2 -type structure. Some conditions for the existence of this structure type are given.

Dimethyl(tert-butyl)-, di(tert-butyl)methyl- and tri(tert-butyl)methylenephosphorane (CH 3 ) n [(CH 3 ) 3 C] 3-n P=CH 2 , 3a-c, (n = 2,1, 0) have been synthesized from the corresponding phosphonium bromides, using standard methods, but under mild conditions. 3 c was found to be thermally unstable, undergoing reductive elimination of isobutene already at room temperature, with di(tert-butyl)methylphosphine as a by-product. 3 b is decomposed similarly above 80 °C. A mechanism for this unusual mode of ylide decomposition is proposed, based on the extreme steric crowding of the molecules. Restricted P–C bond rotation has been detected by 1 H and 13 C NMR spectroscopy for 3 c in toluene solution. Traces of protic species cause a rapid intermolecular H 2 C(P) hydrogen exchange.

Dialkylmethylphosphines R 2 PCH 3 are metallated by tert-C 4 H 9 Li to give LiCH 2 PR 2 (la: R = CH 3 , lb: R. = tert-C 4 H 9 ). la introduces the e CH 2 P(CH 3 ) 2 -ligand into L 3 CoCl to give [xxx] (2). With diorganochlorophosphines R 2 PCl (R = CH 3 , tert-C 4 H 9 , C 6 H 5 ) and with triphenylphosphite P(O Ø) 3 the new biphosphinomethane derivatives (CH 3 ) 2 PCH 2 PR 2 (4 a-c) and P[CH 2 P(CH 3 ) 2 ] 3 (5) are formed, resp.. Tetramethyldiphosphinomethane (3 a) is also obtained from (CH 3 ) 2 PCl and Li 2 CH 2 . Some properties and spectroscopic data of these new materials are described.

Nuclear spin-spin coupling constants 1 J( 31 P- 183 W) are reported of trimethyl element (IVb)-phosphine substituted pentacarbonyl-tungsten complexes of the type [(CH 3 ) 3 E] n PR 3-n W(CO)5 (E = C, Si, Ge, Sn; R = t C 4 H 9 , C 6 H 5 ; n = 0, 1, 2, 3). Variations in the size of coupling constants are shown to depend mainly on the different ligand electronegativities.

Vanadium-51 NMR chemical shifts δ V for a variety of VO 3+ compounds have been found to range from —432 ppm (liquid VOBr 3 ) to + 786 ppm (VOF 3 /CH 3 CN) relative to a liquid VOCl 3 standard. The δ V values and hence the shieldings of the vanadium nucleus are shown to increase in the order VOBr 3 ≪ VOCl 3 < VO(NEt 2 ) 3 < VO(OR) 3 < VOF 3 (1); VOCl 3 < VOCl 2 (OEt) < VOCl(acac) 2 < VOCl(OEt) 2 < VO(OEt) 3 (2); VOCl 2 (OMe) < VOCl 2 (OEt) < VOCl 2 (OPri) < VOCl 2 (OBu t ) (3); VO(OEt) 3 < VO(OBu n ) 3 < VO(OPr n ) 3 ≲ VO(OBu i ) 3 < VO(OPr i ) 3 (4). These trends are elucidated by considering the energy separation between highest occupied and lowest unoccupied molecular orbitals (1,2), inductive and π-transmittance of electron density (1, 2), and hindered σ-donation and expansion of the coordination sphere due to ligand bulkiness (3, 4). High solvent shifts in THF solution suggest complete or partial removal of the halogen from the VO 3+ moiety for VOBr 3 and VOCl 2 (OBu t ). For other compounds, solvent shifts of approximately 30 ppm are likely caused by solvation effects. In the case of VOCl 3 , an equilibrium between solvated VOCl 3 and a species containing THF molecules directly bonded to VO 3+ is proposed. VOCl 3 · 2 RCN (R = Me, Ph) in THF show intact VOCl 3 units : solvent-solute interaction is restricted to the second coordination sphere.

The rate constants of the reaction between benzyl chloride and acetate ion, generated from several alkali acetates and a series of macrocyclic polyethers, were measured under equal conditions. It appears that aminopolyethers are superior to crown ethers in rate acceleration. This behaviour is correlated to the amount of ion-pair separation by certain macrocyclic polyethers, as detected by 1 H NMR spectroscopy, which is a simple method to evaluate the anion activation of every ligand/cation-combination.

The reaction between benzyl chloride and acetate ion, generated from several alkali acetates and a series of macrocyclic polyethers was carried out under similar, heterogeneous solid/liquid phase-transfer conditions. The ability of anion activation of several important polyether ligands is compared. The differences of reactivity among the macrocyclic polyethers in the presence of the same cation are reported. Each ligand can be combined with one certain alkali cation to generate the most reactive species. A model of anion activation under phase-transfer condition is discussed.

As the first ternary calcium chromium sulfide Ca 0,29 Cr 0,48 S was synthesized by firing of stoichiometric mixtures of CaS and Cr 2 S 3 at 950 °C. From strontium and barium only the well-known compounds SrCr 2 S 4 and BaCr 2 S 4 could be obtained. The best methods of preparation for these compounds are the reactions of SrCrO 4 or BaCO 3 and Cr 2 S 3 resp. with H 2 S/H 2 at 950 °C. Whisker-like single crystals of BaCr 2 S 4 are formed by heating of crude BaCr 2 S 4 with AICl 3 . X-ray and IR data of the ternary chromium sulfides are given.

Temperature programmed desorption of pyridine and benzene was carried out on NaX-13, CaNaX and NiNaX. This was correlated with IR investigation of pyridine adsorption according to WARD 3 and with microcatalytic investigations of 2-butanol dehydration and butene isomerisation. Pyridine showed three definite desorption maxima for each of the three zeolites. While the catalytically inactive NaX-13 desorbed pyridine up to 385 °C, the comparable desorption maxima of the active CaNaX and NiNaX were situated at 490 and 470 °C, respectively. IR investigations showed zeolitic cations for these adsorption centres (bands at 1443-1444,1443-1445,1447-1448 cm -1 ). The lower desorption temperature of the system pyridine/NiNaX, compared with CaNaX, is incompatible with the higher acidity of Ni 2+ and the higher IR band level, while the desorption temperature on NaX-13 and CaNaX is conform with the acidity of the ions and the IR band. Benzene on NiNaX behaves in the same way as on NaX-13 (highest desorption temperature 160 °C) while a desorption peak still occurs at 375 °C on CaNaX. The special case of NiNaX is explained by migration of the Ni 2+ into the sodalite cave.

UV irradiation of C 5 H 5 Re(CO) 3 in tetrahydrofuran (THF) yields the THF complex C 5 H 5 Re(CO) 2 THF and traces of [(C 5 H 5 ) 2 Re 2 (CO) 5 ]. C 5 H 5 Re(CO) 2 THF is stable at room temperature, its reaction with N 2 /100 bar yields C 5 H 5 Re(CO) 2 N 2 , which also forms in the reaction with N 2 O whereby the THF complex is partially oxidized and decomposed. The reaction with an excess of N 2 H 4 yields C 5 H 5 Re(CO) 2 N 2 H 4 , the oxidation of which leads to C 5 H 5 Re(CO) 2 N 2 and the by-product trans-N 2 H 2 [C 5 H 5 Re(CO) 2 ] 2 , in which the under ambient conditions unstable HN=NH molecule could be stabilized in a rhenium complex for the first time. In contrast to the analogous manganese complex C 5 H 5 Re(CO) 2 N 2 H 4 disproportionates easily to C 5 H 5 Re(CO) 2 N 2 and C 5 H 5 Re(CO) 2 NH 3 at room temperature; the NH 3 complex can be synthesized directly only by irradiating C 5 H 5 Re(CO) 3 in hexane in the presence of NH 3 . The complexes are characterized spectroscopically and by elemental analyses; the different electronic influence of the nitrogen ligands on the C 5 H 5 Re(CO) 2 system is discussed.

trans-Bromotetracarbonyl(phenyl- or -methylcarbyne)chromium react at elevated temperatures to yield tolane and dimethylacetylene, respectively. On warming trans-bromo-tetracarbonyl(phenyl- and -p-tolylcarbyne)chromium phenyl-p-tolylacetylene is formed as well as both the symmetrical alkynes tolane and di-p-tolylacetylene.

An one-step synthesis of benzocyclobutene (2) by gas-phase pyrolysis of indane-2-one (1) has been found. By the same method indane-1-one (3) and naphthoquinone(1,4) (5) gave indene-1 -one (4) and fluorene-9-one (7) formed biphenylene (8).

The hydrolysis of benzyltriesters of adenosine 3′,5′-cyclophosphate with H 2 18 O was undertaken. The mass spectra of the benzylalcohol fragments contained the label whereas the cAMP after derivatisation with trimethylsilyl-groups did not show an enhanced M + 2 peak. This clearly indicates that the benzylic C–O bond is broken during hydrolysis.

The eight epimeric 3,4-dimethyl-l,2-cyclopentanediols have been investigated as bistrimethylsilyl (TMS) ethers and as diacetates by means of isobutane chemical ionization (CI). Correlations between stereochemistry and CI spectra appear to be limited in the case of the TMS ethers. All eight diacetates, however, can be unequivocally identified from their isobutane CI spectra.

The 13 C NMR spectra of 1-hydroxynaphthalene-3,6-disulphonic, 1-hydroxynaphthalene- 3,8-disulphonic, 2-hydroxynaphthalene-3,6-disulphonic, and 2-hydroxynaphthalene-6,8-disulphonic acids were determined with and without noise-decoupling. The fine splitting caused by the long-range couplings pattern was used in the identification of the resonances lines of the 13 C nuclei. The combined influence of the mesomeric effect of the hydroxyl group and that of the sulphonate groups have been discussed.

7,14-Diacetyl-6,13-dihalo-3,10-diethoxytriphenodithiazines have been synthesised by reductive acetylation of 6,13-dihalo-3,10-diethoxytriphenodithiazine with Zn dust (Ac 2 O) pyridine. Attempts to synthesis 7,14-dihydro-6,13-dihalo-3,10-diethoxytriphenodithiazine is failed. Oxidation with 30% H 2 O 2 in AcOH of 7,14-diacetyl-6,13-dihalo-3,10-diethoxytriphenodithiazine did not produce its S,S-dioxide. 3-Acetoxy-7-ethoxy-1,2,4-trihalophenothiazine on treatment with 30% H 2 O 2 in AcOH regenerated 7-ethoxy-1,2,4-trihalo-3H-phenothiazine-3-one by oxidative deacetylation. Their R i values and IR spectral data have been recorded.

Quantitative kinetic results of the intermediates and end products of the formose reaction are obtained for the first time by the application of high pressure liquid chromatography. A mechanism for the secondary reaction step of the formose reaction in the presence of excess formaldehyde is derived from these results : Formaldehyde adds successively to intermediates and the formation of xylose is highly favoured. All results are characteristic for typical aldol-type reactions. Almost no cleavage of the intermediate and end products is observed.

Single crystals of the hitherto unknown compound CaFe 6 Al 6 O 19 were examined by X-ray work. It is isotypic with the magnetoplumbite structure (a = 562.8, c = 2208. 4 pm, space group D 6h 4 -P6 3 /mmc). A discussion of the statistical distribution of Fe 3+ and Al 3+ with respect to other compounds of this type is given.

Ba 2 MnTe 3 has been prepared and analytically and structurally characterized. It crystallizes orthorhombic with a = 972(2) pm, b = 473(1) pm, c = 1898(4) pm, Pnma and is isotypic to Ba 2 MnS 3 and Ba 2 MnSe 3 .

Force field calculations of a series of bridgehead olefins give nonplanar double bond deformation energies which are correlated with chemical stability (reactivity) properties. Minimum potential energies allow an interpretation of experimental relative yields of isomeric bridgehead olefins with the same carbon skeleton. Pyramidal distortions (outof-plane bending) at the sp 2-carbon atoms are often found to contribute more prominently to the non-planar double bond deformations than pure twisting. Qualitative rules proposed in the past as to reactivity, thermodynamic stability, and structure of bridgehead olefins do not always agree with the computational results.