Volume 31, Issue 3

The title compound crystallizes in the monoclinic system with dimensions of the unit cell a = 14.09(2), b = 8.60(1), c = 11.34(1) Å and β = 101.7°. The space group was determined to be A 2/a with four molecules in the unit cell. The structure was solved by direct methods, and all hydrogen atoms were located. Full matrix refinement led to R = 0.059. The B 2 N 4 six membered ring is nonplanar as expected for an 8π electron heterocycle. The molecule possesses C 2 symmetry but the ring itself is near the D 2 symmetry as derived from earlier CNDO/S-calculations. The BN bond lengths are 1.43 A, the NN distances 1.43 Å and the average CN distances 1.44 A. The boron atoms and four of the six nitrogen atoms are trigonal-planarly coordinated while the remaining two N-atoms (N 1 ,N 2 ) deviate little, but significantly, from sp 2 hybridisation. The structure of the molecule can be interpreted as the best compromise between ΒΝ-π-bonding, nonbonding repulsion between adjacent CH 3 groups, and the interaction between neighbouring ‘free pairs of electrons’ of the ring N-N-units.

Halides and pseudohalides of formula π-C 7 H 7 M(CO) 2 X were synthesized by reaction of [π-C 7 H 7 M(CO) 3 ][BF 4 ] and π-C 7 H 7 M(CO) 2 Br, with NaX or KX (M = Mo, X = OCN-, SON-, N 3 -; M = W, X = Cl-, Br-, OCN-, N 3 -). In the OCN - and SCN - complexes the ligands are coordinated by the nitrogen atoms. The reaction of [π-C 7 H 7 W(CO) 3 ][BF 4 ] with KOCN yielded (besides π-C 7 H 7 W(CO) 2 NCO) a compound which proved to be the mono-tricarbonyl-tungsten derivative of bicycloheptatrienyl (C 7 H 7 ) 2 W(CO) 3 . This compound could also be isolated from [π-C 7 H 7 W(CO) 3 ][BF 4 ] and Na[NCNH]. Ring contraction occurred when [π-C 7 H 7 W(CO) 3 ][BF 4 ] was treated with Na 2 [NCN].

Tetraformatozirconium(IV), Zr(OOCH)4 and diformatoxozirconium(IV)dihydrate, ZrO(OOCH)2 · 2 H 2 O have been prepared by the reactions of tetrachlorozirconium(IV) and dichloroxozirconium(IV) with anhydrous formic acid, respectively. The compounds have been characterized by elemental analyses, molar conductance, thermogravimetry and infrared spectral data. The compounds are nonelectrolytes in nitrobenzene and have polymeric structures.

The reactions of 2-dimethylamino-[1,3,2]oxathiarsolane with secondary amines lead to the formation of 2-dialkylamino-[1,3,2]oxathiarsolanes. IR, 1 H NMR and mass spectral data are presented and discussed.

The reactions of the tri- and tetrafunctional alcoholes CH 3 C(CH 2 OH) 3 and C(CH 2 OH) 4 with the aminoarsines (CH 3 ) 2 As—N(CH 3 ) 2 , CH 3 As[N(CH 3 ) 2 ] 2 , and As[N(CH 3 ) 2 ] 3 are examined. The reactions lead by cleavage of the As—N-bond to the formation of acyclic and mono- and bicyclic arsinous acid esters.

Single crystals of the quenchable high pressure phase Tm 2 S 3 -II were grown from a TmJ 3 -flux at 10 kbar, 1600°C. The crystals are monoclinic, space group P2 1 /m, with a = 11.110(5) Å, b = 3.874(3) Å, c = 10.872(5) Å, β = 108.88(2)° and Z = 4. In Tm 2 S 3 -II, which is isotypic with Er 3 ScS 6 , the four independent thulium atoms are coordinated by six (2 x), seven and eight sulfur atoms.

The change of the yellowish solution of MoO 3 in concentrated sulfuric acid into a dark blue colour by diluting with water has its maximum at H 2 SO 4 · 2,85 H 2 O. Spectralphotometric measures show a significant difference to the colour of solutions containing molybdenum-blues.

Three different polymorphs of FeNbO 4 were prepared by chemical transport. One of them is a new modification, which crystallisizes in the GaNbO 4 -type, monoclinic, space group C2, a = 12.52 Å; b= 3.83 Å; c = 6.67 A; β = 107.5°. The detailed structure, composed of 2 x 2 ‘blocks’ of corner shared metal-oxygen octahedra, was investigated by electron-diffraction and two-dimensional high resolution electron microscopy.

Pyridine π-complexes are prepared by treating 2,6-dimethylpyridine and 2,3,5,6-tetramethylpyridine with Cr(CO) 6 . Thus, tricarbonyl(2,6-dimethylpyridine)chromium(0) and tricarbonyl(2,3,5,6-tetramethylpyridine)chromium(0) are obtained. IR and 1 H NMR spectra are discussed together with those of tricarbonyl(pentamethylpyridine)chromium(0) and tricarbonyl(2,4,6-trimethylpyridine)chromium(0).

Mass spectra of several fluoroboron and phenylboron chelates were compared with regard to the influence of the boron substituent F and C 6 H 5 . The fragmentation pattern depends very strongly on the type of the substituent. In the case of the fluorine substituent, the three bonding states of boron will be reached preferably by opening the chelate ring. For the substituent C 6 H 5 this state of boron will be reached by elimination of C 6 H 5 .

Crystalline complexes of some alkali and alkaline earth perchlorates and picrates with macrocyclic polyethers have been synthesized. With the alkyl substituted aromatic macrocyclic polyethers bis(3,5-di-tert-butylbenzo)-18-crown-6 and bis(4-hexadecylbenzo)-18-crown-6 it was not possible to isolate all the complexes in the crystalline form. In fact the steric hindrance, caused by the alkyl substituents, affects the stability of the complexes and hinders the possibility of isolation. It has been observed that also the molecular structure and the electronic configuration of the anion are important factors in determing the formation of crystalline complexes. The complexes obtained were identified and characterized by elemental analysis, IR, UV and 1 H NMR spectra, conductivity and x-ray powder analysis.

The complicated and partially controversial formulations of the various steps and branchings in the hydroformylation process are comprised in a reaction scheme that neglects the production of different isomers and isomerisations of olefins and is a compromise between the given complexity and a theoretical tractability. Special consideration is devoted to the inhibition of the process by one of its substrates, CO. In a first approximation complete inertness of the Co-tetracarbonyls is assumed and the existence of bistability and hysteresis for particular parameter combinations is proved. In the further treatment this approximation is again relaxed. Technological consequences of the analysis are discussed.

Using three dimensional X-ray data collected on a four circle diffractometer, the structure of (CO) 9 Co 3 COBBr 2 N(C 2 H 5 ) 3 was solved by Patterson and Fourier methods. Least squares refinement with a block-diagonal matrix leads to a reliability index of R = 10.7%. Crystal data: α = 13.277(6) Å, b = 10.17(1) Å, c = 9.22(2) Å; α = 91.12(6)°, β = 87.61(4)°, γ = 98.79(2)°; space group P1̅; Z = 2; V = 1229,7 Å 3 ; D x = 1.97 gcm-3.

UV irradiation of 2-bromothiophene or 3-bromothiophene in various organic solvents produces thiophene as one of the reaction products. The likely mechanism in the case of 2-bromothiophene involves the formation of a π-complex between the thienyl radical and the bromine atom.

The kinetics of the chlorine exchange between antimony (III)-chloride and hexachloropropene has been studied in systems SbCl 3 /C 3 Cl 6 /CH 2 Cl 2 /electron donor. Donors are benzene, toluene, ethylbenzene, n-propylbenzene, cumene, naphthalene, anthracene, biphenyl, p-terphenyl. A decrease of the velocity of the chlorine exchange ist effected by the donors. Studies with benzene as donor show, that the decrease depends only on the concentration of the donor. For benzene and alkylbenzenes a donor constant is defined which correlates with the Taft constant for the substituents.

The axial preference of fluorine substituent at phosphorus involved in 4-methyl-1,3,2-dioxaphosphorinanyl ring system was established. Cis-trans geometry in this family of compounds was assigned by chemical correlation and by means of 1 H, 13 C, 19 F and 31 P NMR.

The photoionization process of indole in alkaline aqueous solutions at 77°K and the recombination process of trapped electron with its mother molecule were investigated. The fluorescence spectrum of indole in these glassy media depended on the NaOH concentration; the disappearance of the 325 nm band at the NaOH concentrations higher than 5 M with the appearance of a fluorescence band at 375 nm. The latter emission is possibly ascribed to the fluorescence of indole anion formed by proton dissociation in the excited singlet state of indole. The intensities of the 375 nm band and the ESR signal due to trapped electrons were dependent on the NaOH concentration and increased steeply with increasing the NaOH concentration. There was a parallel relation between the indole anion concentration and the trapped electron density to some extent. The dependence of the ESR signal intensity on irradiation intensity suggested that the photoionization of indole in alkaline aqueous solution occurred through a two photon process. The presence of a photoactive intermediate for absorbing the second photon was further investigated with simultaneous irradiation of two different wavelength lights. The trapped electron was detrapped with the irradiation of visible light (e.g. 580 nm), and its recombination with mother molecule caused an emission with the same spectrum as indole phosphorescence. The molecular species of the photoactive intermediate in alkaline aqueous solutions seems to be the indole anion. The photoionization in NaOH aqueous solution at 77°K was also compared with that in methanolic glassy solution.

Electrophilic substitution of 2,5-diphenyltellurophene (1) affords 2,5-diphenyl-3,4-chloromethyl-tellurophene (2). The reaction of 2 with nucleophilic reagents leads to the tetrasubstituted derivates (3-6). Oxidation of 5 with seleniumdioxide affords 2,5-diphenyltellurophene-3,4-dicarbaldehyde (7).

Condensation of 2-arylhydrazones of indandione-1,3 with malononitrile in alkaline medium leads to 3-aryl-1-cyano-5-dicyanomethylen-2-imino-2,3-dihydro-5 H-indeno[2,1-c]-pyridazines (2). Starting with 2-arylhydrazones of cyclohexanedione-1,3 the reaction is accompanied by dehydrogenation and 2-amino-4-cyano-8-dicyanomethylene-2-aryl-2,8-dihydro-cinnolines (5) are yielded.

The arylidene derivatives (1) of 3-phenyl-1,3-thiazolidine-2,4-dithione undergo 1,4-cycloaddition reaction with acrylonitrile, ethyl acrylate, ω-nitrostyrene, styrylethyl ketone and N-arylmaleimides leading to substituted tetrahydrothiopyrano-7 H[2,3-d]thiazole-2-thiones (2) and (3). The bactericidal and fungicidal activities of the new products were tested.

2-Phenylhydrazono-4-thiazolidinone (1) and its 5-substituted derivatives (4) and (6) were cyclized by formaldehyde or aromatic aldehydes to afford the corresponding 2-phenyl-tetrahydrothiazolo[2,3-c]-1,2,4-triazol-5-ones (2, 3) and (7). Compounds 3 were also obtained by the action of aromatic aldehyde on 2-phenyltetrahydrothiazolo[2,3-c]-l2,4-triazol-5-one (2).

In the temperature range from 54 to 75°Ca new modification of KNH 2 was found, which crystallizes tetragonally a = 4.282 ± 0.003 Å, c = 6.182 ± 0.003 Å, and c/a = 1.444 (60°C), in P4/nmm - No. 129-, Z = 2, 2 K in 2c 0 1/2 z, z = 0.202(5), 2 N in 2c 0 1/2 z, z = 0.737(15). Its structure is of a deformed sodium chloride type.

A catalytical system for homogeneous hydrogenation of unsaturated compounds, operating under mild conditions can be prepared with H 2 PtCl 6 -SnCl 2 · 2 H 2 O and the additives HBr and H 2 O in iso-propanol. Reaction rates up to 32 mMol · l -1 · min -1 were observed. After hydrogenation of one batch new substrate can be injected several times without noticeable desactivation of the system. Hydrogenation rate of 2-tr-cis-hexene is only 0,5 times less than of 1-hexene. Mesityloxide is selectively hydrogenated regarding the double bond.

It has been reported from this Laboratory that 1 J PH and 1 J PSe absolute values showed the clear dependence on the spatial orientation of H and Se substituents in several pairs of ring C-substituted 2-X-2-Y-1,3,2-dioxaphosphorinans and may therefore provide information about conformation of the ring and configuration at phosphorus atom 1 .

Isolation, Diphenylpicrylhydrazyl Products and yields for the electron radiolytical decomposition of DPPH in tetranitro methane have been determined. Reaction occurs via attack of NO 2 radicals, the dinitro adduct being the main product at the lowest doses investigated.

Various naphthacenequinones can be synthesised by hydrogenation of the Diels-Alderadducts of p-benzoquinone with Zn/acetic acid followed by a condensation of the formed diketones with o-phthalaldehyde.

Synthesis of a few bis(diguanido-oxy)-alkanes which are likely to possess good bacteriostatic properties have been reported.