Volume 29, Issue 7-8

The new compounds CaCuSb(Bi) and SrCuSb(Bi) were prepared and their structures determined. They crystallize in the „filled“ NiAs-(Ni,In)-structure.

The new compounds Ca 5 Si 3 and Ca 5 Ge 3 were prepared and their structure determined. They crystallize in the Cr 5 B 3 -structure type.

A new SrSi-modification and the new phase SrGe 0,76 were prepared and their structures determined. In these compounds the elementlVatoms form planar hexagons substituted in the 1, 2, 4, 5-positions by four additional Si(Ge)atoms. In the compound SrGe 0,76 there are defects in this unit in the positions 1, 2, 4, 5, while in SrSi no indications of such defects could be found.

The complexes [π-C 5 Η 5 Μ(CO) 3 ] 3 (M = Cr, Mo) and Tl(π-C 5 H 6 )Cr(CO) 3 have been prepared in quantitative yields by the reaction of [π-C 5 H 5 M(CO) 3 ] 2 (M = Cr, Mo) with metallic thallium. The reactions of Tl(π-C 5 H 5 )Cr(CO) 3 with I 2 and [π-Ο 5 Η 5 Cr(CO) 3 ] 2 are described.

The tetramethylammoniummolybdate [N(CH 3 ) 4 ] 2 Mo 8 O 25 · 5 H 2 O, obtained from an aqueous solution, belongs to an as yet unknown polymolybdate structure type. The manner of the water attachment was explored by thermal dehydration, wide line NMR spectroscopic methods as well as by the comparison of its IR spectrum with the deuterated analogs. The vibration spectra are discussed. Cell constants were determined by X-ray techniques.

The photoelectron (PE) spectra of five boron-substituted derivatives of tetrazadiborine are presented. They are discussed on the basis of a structural model (twist form of the ring system) which results from simple extended HÜCKEL calculations. Orbital energies calculated by the CNDO/S method agree quite well with observed ionization energies. According to these at least the first three bands correspond to ionizations from π-orbitals. Evidence for strong π-interactions can be deduced by comparison with PE spectra of diaminoboranes.

The ylides (CH 3 ) 2 C 6 H 5 P = CH 2 and CH 3 (C 6 H 5 ),P=CH, have been prepared via their trimethylsilyl derivatives in a pure and salt-free state. Their properties and some spectroscopic data are reported. The thermal decomposition leads to the corresponding methylphenylphosphines, the addition of methanol yields a phosphine oxide and alkane or a phosphine an anisol, depending on the number of aryl groups at phosphorus. There is evidence for a pentacoordinate tetraorgano-alkoxyphosphorane as an intermediate. Protic catalysts are found to cause rapid α-proton exchange in the ylides.

The electrochemical reduction of diazoacetone in 10 % water: ethanol solution, between pH = 3 and pH = 9, has been studied. Two waves have been observed in acid solution: the first is attributed to the reduction of diazoacetone to aminoacetone and the second one to the reduction of 2,5-dimethyldihydropyrazine (formed by dimerization of the aminoacetone) to 2,5-dimethylpiperazine. In neutral and alkaline media the first wave splits into two waves corresponding to a reduction of diazoacetone to hydrazone and aminoacetone.

A reinvestigation of the title compound is reported. The compound has been prepared by a modified method and characterised by infrared spectra, electronic spectra and magnetic susceptibility measurements. The infrared spectral data suggest that the two coordinated thiocyanate ions are bonded to chromium(III) through N atoms rather than the S atoms. The complex exhibits two ligand field bands at 20410 and 26660 cm -1 due to the transitions 4 A 2 g → 4 T 2 g and 4 A 2 g → 4 T 1 g (F) respectively. Electronic spectral and magnetic moment data suggest that the complex has an octahedral structure with d 2 sp 3 bonding.

29 Si NMR measurements show that in waterglass solutions the silicon exists mainly in the form of tetrafunctional branching groups (-107.2 ppm), trifunctional branching groups (—94.6 ppm), middle groups (—86.6 ppm) and end groups at —77.4 ppm. The ortho-silicate anion resonance was found between — 68.7 and —72.3 ppm. The variation is probably due to different degrees of ionization.

By means of a spectrophotometric titration at many wavelengths it is possible to determine the uniformity („Einheitlichkeit“) of the system, respectively, the number and kind of dissociable groups. Isosbestic points, absorbance-, absorbance-difference diagrams and other graphs are used for the analysis of spectrophotometric titration data. Different methods for determination of absolute pK-values of one-step titration systems are compared critically. To avoid the problems of electrometric pH-measurements some new methods are proposed to evaluate relative pK-values ( Δ pK -values) by means of a simultaneous titration of a protolyte together with a standard substance. The efficiency of these relative methods is demonstrated using two compounds with a very small pK-difference (o- and p-nitrophenol, Δ pK = 0.1). The results are controlled by simulation with a digital computer.

The near and far UV spectra of the aminoboranes (Me 2 N) n B X 3-n , n = 1, 2, 3, Me=CH 3 , X= H, Me, F, Cl, Br are presented. In most of the monoamino boranes the π→π * transitions dominate. In the di- and triamino boranes there were additionally found a Rydberg series and some single Rydberg transitions, partly preceding the π→π * band. The Rydberg assignments were settled particularly by comparing the band positions of the compounds relatively to their ionization energies.

The magnetic susceptibilities and magnetic moments of the ammonium salt of cupferron and manganese, cobalt, nickel and copper divalent complexes are investigated. The ammonium salt of cupferron is diamagnetic while the divalent transition metal cupferron complexes exhibit paramagnetic behaviour. For manganese, cobalt and nickel cupferrates the magnetic moment is smaller than the spin-only value, which reflects the effect of the orbital angular momentum and electron delocalization. For copper cupferrate the magnetic moment is nearly equal to the spin-only value.

Coordination compounds of formula Ni(Iz) n X 2 (H 2 O) m , in which Iz=imidazole, n = 1, 2, 4, 6, m = 0-4, and X = Cl-, Br-, I- and NCS-, are described. The anhydrous compounds are prepared from ethanolic solutions of Iz and nickel(II) salts in stoichiometric amounts in the presence of the dehydrating agent triethylorthoformate. Without this dehydrating agent hydrates are isolated for n = 2,4 and 6 with X = Cl, Br. The compounds were identified by means of infrared spectra (4000-25 cm -1 ), ligand-field spectra (35000-4000 cm -1 ) and X-ray powder diagrams. Compounds of formula [Ni(Iz) 6 ]X 2 all contain octahedrally coordinated Ni 2+ , for which the spectrochemical parameters were obtained. Tetragonal Ni 2+ ions occur in [Ni(Iz) 4 X 2 ] in which X = Cl and NCS, and in [Ni(Iz) 4 (H 2 O) 2 ]X 2 in which X = Cl and Br. These compounds are paramagnetic and the crystal-field parameters for tetragonal symmetry have been calculated. In [Ni(Iz) 4 ]X 2 with X = I and Br, the Ni 2+ ions are square-planar coordinated with anions in the second coordination sphere, resulting in orange-coloured diamagnetic compounds. Anion-bridged distorted octahedrally coordinated Ni 2+ ions probably occur in the compounds of formula Ni(Iz) 2 X 2 , in which Iz takes the axial positions. Similar structures are suggested for the mono-imidazole compounds, NiIzX 2 .

Quinine free base forms the following complexes with transition metal chlorides: 2 quinine · 3 CuCl 2 , quinine · 2 CuCl 2 , quinine · 2 NiCl 2 · 8 H 2 O, quinine · 2 NiCl 2 , quinine 2 CoCl 2 and quinine · 3 CrCl 3 · 6 H 2 O. Comparison of the IR spectrum of the quinine free base with the spectra of the complexes leads to the assumption that the transition metal ion is coordinated with the quinuclidinic and quinolinic nitrogens. Chelation with the hydroxyl oxygen is tentatively proposed. The visible UV spectra and the magnetic moments of the complexes are also reported and discussed.

The synthesis, IR spectra and UV-visible diffuse reflectance spectra of the complexes [Cu(abeda)]Cl 2 and [Ni(abeda)]Cl £ , where abeda = N,N′-bis(o-aminobenzyl)ethylenediamine, as well as the magnetic moments of the complexes in the solid state are reported and discussed.

Coordination compounds of some nickel (II) salts derived from 1,3-bis(di-n-propyl-phosphinyl)guanidine (DPPG) have been synthesized and characterized from their chemical analyses, infrared spectra, electronic spectra, conductance and magnetic moment measurements. With nickel perchlorate, an octahedral complex of the type [Ni(DPPG) 2 ](ClO 4 ) 2 has been prepared, while with corresponding chloride and iodide square planar compounds of the type [Ni(DPPG)X]X have been obtained. With nickel sulfate a 1:1 diamagnetic complex is formed in which sulfate ion is unidentately bound. In all the complexes DPPG acts as a tridentate ligand and bonding takes place from two P = O groups and the imino nitrogen atom. The solvation behavior of the complexes has also been studied.

The photoelectron spectroscopic investigation of the unconjugated spiroketone of 1,3-oxathiol (1) shows that there is no significant interaction between the carbonyl group and the hetero-π-system, whereas in the UV-spectrum of this compound a long-wave band is measured, which can be assigned to an intramolecular charge-transfer and which causes the yellow colour of this aliphatic ketone.

The direct synthesis of (iso)alloxazine N-oxides using trifluoroperacetic acid in situ is reinvestigated, showing sensitivity towards steric (peri) hindrance. The photoreduction of these N-oxides in the presence of 1,4-cyclohexadiene yields the parent (iso)alloxazine. The reduction of the N-oxides by initially formed dihydro (iso)alloxazine is ruled out for the photoreduction.

Reactions of N-pyridinium phenancylides with different a, β-unsaturated ketones give 2,4,6-triarylsubstituted pyridines, 2,6-diphenyl-4-(2-pyridyl) pyridines, 2-benzylidene-4,6-diphenyl pyridines and 2,4,6-triphenyl-3-bromopyridine. Ammonium acetate in acetic acid was used as cyclization agent. The structure of the products are supported by IR and NMR spectra.

Four molecules of quaternary salts of nicotinamide form a condensation product of structure 2. It has been studied with the model substances 1d—q which elements of structure promote or prevent formation of the cyclocondensation product.

Gold(III)oxidchloride AuOCl is obtained by the treatment of Au 2 O 3 with concentrated perchloric acid at 160°C in a sealed pyrex tube. The crystals have been characterized by X ray and IR spectrum. Above 290°C AuOCl decomposes to Cl 2 , O, and Au.

Disproportionation, Denitration Disproportionation dominates the second order reactions of the OH adduct to acinitromethane and leads to production of nitrite ion.

Hydrostannation of diethylamino-dipropinylborane leads to the new heterocyclic system of a 1-bora-4-stannacyclohexadiene.

The magnetic susceptibilities of some newly syntesized Al(III) and Si(IV) complexes of Schiff bases derived from the condensation of o-hydroxyacetophenone or 2-dydroxy-1-naphthaldehyde with hydroxyalkylamines or diamines have been measured and the data indicate their diamagnetic character.

According to equations (1) and (2) new bis(organosulfinato)mono and bis(pyridine) complexes of zinc with coordination numbers 4, 5 and 6 are described. The structures are discussed pn the basis of the IR spectra of the compounds.

The pulse radiolysis of aqueous solutions of selenomethionine has been studied under both neutral and acid conditions and the transient optical absorption spectra have been observed. The reactivities of both eāq and OH radicals have been measured as well as the formation and the decay kinetics of the transient species.

The coupling constants 2 J( 1 H -115 Sn) of 14 methyltin compounds have been measured. They show a good agreement with the calculated values.

Two isomers of the linear tetratertiary phosphine (C 6 H 5 ) 2 ΡCH 2 CH 2 Ρ(C 6 H 5 )CH 2 H 2 Ρ(C 6 H 5 )CH 2 CH 2 Ρ- (C 6 H 5 ) 2 with widely differing solubilities and melting points can be obtained from the base-catalyzed addition of C 6 H 5 P(H)CH 2 CH 2 P(H)C 6 H 5 to two equivalents of diphenylvinylphosphine; these appear to be the dl and meso diastereoisomers arising from the two equivalent asymmetric phosphorus atoms.

By the reaction of two equivalents of butyllithium with N-benzyl-N,N′-diorganylureas, no dimetallated ureas were recovered; rather intensive-coloured solutions were formed, with subsequent identification of N, α-diorganylbenzylamnines and lithiumcyanate.