Volume 35, Issue 12

The structure of the title compound (a = 1185.4, b = 1197.7, c = 1764.8 pm, β = 73.96°, space group P2 1 /c) has been determined from X-ray diffractometer data. The molecule is structurally analogous to the tetraborate ion [B 4 O 7 ] 2- . The eight-membered ring is folded by 104° about the B - B vector. The boron atoms are more strongly bonded to the bridging oxygen [B-O(B) 139 pm] than to the other atoms [B-O(C) 155 pm, B-N 160 pm, B-Cl 182 pm].

1,3-Dilithio-5-trimethylsilyl-2,2,4,4,6,6-hexamethylcyclotrisilazane (1) reacts in a 1:2 molar ratio with difluorodimethyl- or trifluoromethylsilane to give substitution at the lithiated N atoms. The reaction of the bis(fluorodimethylsilyl)-substituted compound with more of 1 produces ring contraction, to form a silyl-bridged tris(cyclodisilazane). In the reaction of the bis(difluoromethylsilyl)-substituted cyclotrisilazane with more of 1, however, the title compound, a fused ring system, is formed. This compound has been characterised by crystal structure determination. The mechanism of its formation is discussed.

Potassium tetrachloroplatinate and asparagine form a paramagnetic complex in aqueous solution. This complex which displays a blue green color has been studied by ESR and IR spectroscopy. The ESR spectra are interpreted to be due to tervalent platinum in a low spin d 7 configuration. The IR data suggest that the doubly deprotonated ligand is coordinated through the COO - and CONH - groups.

NH 4 CuS 4 was prepared according to syntheses reported in the literature. Orthorhombic crystals could be grown (P2 1 2 1 2 1 , a = 5.249(1), b = 8.444(2), c = 12.782(2) Å , Z = 4), the structure of which was solved from X-ray diffractometer data (R = 0.031 for 767 obs. reflections). In the solid state (CuS 4 ) - -chelate rings are linked via additional Cu-S-bonds to form one-dimensional polymeric anions.

The reaction of 1,1,1-tris(diiodoarsinomethyl)ethane, CH 3 C(CH 2 Asl 2 ) 3 (1) with NaAs(C 6 H 5 ) 2 in the molar ratio of 1:3 gives 4-methyl-1,2,6-triarsa-tricyclo[2,2,1,0 2,6 ]-heptane, CH 3 C(CH 2 As) 3 (2). The previously synthesized CH 3 C(CH 2 AsS) 3 (4) can be desulphurated with triphenylphosphine to yield also 2. The reaction of 1 with NaSeH gives the new cage compound 6-methyl-1,3,4-triarsa-2,8-diselena-tricyclo[3,3,1,0 3 ,4 ]-nonane, CH 3 C(CH 2 As) 3 Se 2 (5).

The formerly described compound Ca 2 Sb is to be corrected to Ca 4 Sb 2 O as shown by X-ray diffractometer data of single crystals and neutron diffraction diagramms of powders. The compound crystallizes in the K 2 NiF 4 structure type.

Osmiumpentachloride is prepared by the reaction of osmiumtetroxide with sulfur - dichloride. X-ray powder data gave identical results with those of other authors; however, the IR spectrum differs from the reported data. With AsPh 4 + Cl - in trifluortrichlorethane suspension the complex AsPh 4 [OsCl 6 ] is formed, which can easily be reduced by dichloromethane to osmium(IV), forming the well known hexachloroosmate(IV), (AsPh 4 ) 2 [OsCl 6 ].

The reaction of PCl 3 with ClN 3 at -78 °C probably yields the extremely explosive PCl 4 N 3 ; at higher temperatures (-10, 20 °C) [Cl 3 PNPCl 3 ]Cl is formed. From PPh 4 [I(N 3 ) 2 ] and PCl 3 the cyclophosphazene (NPClN 3 ) 3 was obtained, probably via the intermediate PCl(N 3 ) 2 - (NPClN 3 ) 3 consists of a mixture of the syn and anti isomers and was characterized by its 31 P NMR, IR and Raman spectra.

The complex between the polyether ligand 1,11-bis(tropolone)-3,6,9-trioxaundecane and RbI crystallizes in space group P2 1 /c with cell dimensions a = 11.383(4), b = 14.493(5), c = 16.122(6) Å and β = 111.02(5)° with Z = 4. The structure was solved on the basis of 3734 X-ray reflections measured on a diffractometer with CuK α -radiation and refined to an R of 0.101. The polyether wraps around the Rb + in a circular structure. One of the tropolone rings is elevated in order to avoid collision. Rb + is located 1.224(6) Å above the plane formed by five oxygen atoms of the ligand, it is coordinated to I -(3.666(2)Å) and to all oxygens. The Rb + ··· O distances of the least electronegative “ester oxygens”, 3.14(1) Å and 3.18(1) Å are significantly longer compared to the other Rb + ···O distances in the range 2.81(1) Å to 3.08(1) Å. The conformation about the C-C and C-O bonds of the ligand are gauche and trans as generally found in such molecules. The two tropolone seven-membered rings are slightly non-planar and display an envelope-type structure.

In a heterogeneous electrolyte system of a strongly basic anion exchanger and solutions of NaBF 4 or NaClCO 4 we established the influence of the nature and concentration of the eluent in chromatographic experiments on chlorine isotope separation. Results show that when the electrolyte concentration is increased the degree of isotope separation decreases. With NaBF 4 the separation factor is greater than with NaClO 4 under conditions which are otherwise the same. For electrolyte solutions containing ClO 4 - , NO 3 - and BF 4 - there is a linear relation between the separation factor of the chlorine isotopes and the logarithm of the heat of anion hydration of the elution electrolyte.

Isotetrasilanes with the general formula XSi(SiY 3 ) 3 (X = F, Cl, Br, I, CH 3 , OCH 3 ; Y = CH 3 , OCH 3 , Cl) were studied by 29 Si and 13 C NMR. One-bond coupling constants between the silicon nuclei as well as between carbon and silicon were studied. It was found, that the magnitudes depend not only on the electronegativity of X and Y, but also on the steric effect of the substituent X.

The crystal structure of the complex compound of SbCl 3 with a chelating bipyridyl group was determined. Sb(C 10 H 8 N 2 )Cl 3 crystallizes in the space group P2 1 /c with a = 818.9(4), b = 695.8(7), c = 2331.3(12) pm, β = 103.59(4)° and Z = 4 molecules per unit cell. The SbCl 3 fragment is T-shaped with <Sb-Cl> at 254.7 pm. Taking into account also the N atoms of the chelating 2,2′-bipyridyl group (<Sb-N> = 228.1 pm) and an intermolecular Sb···Cl contact at 334.0 pm the Sb coordination is distorted octahedral.

Reaction of dichlorophenylarsane complexes with acetylacetone gives 1,3,2-dioxa arsorine systems, in which both chlorine functions are substituted by the oxygen atoms of one acetylacetone moiety bonded in its diene diol form. Properties and spectra of (CO) 5 CrAsPh(C 5 H 6 O 2 ) and η 5 -C 5 H 5 (CO) 2 MnAsPh(C 5 H 6 O 2 ) are described; the structure of the (CO) 5 Cr complex was established by an X-ray analysis.

Alcoholato complexes of cobalt(II) chloride with the general formula, COCl2 · xROH (where R = Me, Et, Pr i , Bu i , Bu n , Bu s and Bu t ) have been synthesised by the reactions of anhydrous CoCl 2 with an excess of the appropriate alcohols under reflux. Physicochemical studies such as electronic, infra-red spectra, magnetic and conductivity measurements have been carried out to throw light on the structure of these complexes. Magnetic and electronic spectra suggest an octahedral environment for cobalt(II) in the methanolato complex and tetrahedral geometry for all other complexes.

The aminolysis of (NPCl 2 ) 2 NSOPh by methyl-and ethylamine in diethylether proceeds mainly via a non-geminal substitution pattern. In acetonitrile both geminal and non-geminal substitution is observed. The preparation of the derivatives is described and the 1 H and 31 P NMR data are discussed. The interpretation of the NMR spectra is supported by the simulation of the spectra of NPClNHMeNPCl 2 NSOPh.

4-Nitrobenzylidenedimethylsulfurane, a semi-stabilized sulfonium ylide has been generated by the attack of methylsulfinyl carbanion in dimethyl sulfoxide and reacted with a series of substituted benzaldehydes, furfural and benzylideneacetophenone to afford trans-1,2-disubstituted epoxides in fair to good yields. The structural assignments of the products are based on IR and NMR spectral evidences.

The structure elucidation of 8-hydroxy-4-methoxy monothioquinaldic acid -a meta-bolite from Pseudomonas fluorescens -is described.

In order to study the structure dependence of the 13 C,H couplings in the fulvene system the 1 H-coupled 13 C NMR spectra of 6,6-disubstituted fulvenes (R = R′ = C 6 H 5 , CH 3 , cyclopropyl and N(CH 3 ) 2 ) were recorded and the interesting couplings determined with high accuracy by complete analysis. They have values typical for unsaturated five membered rings with vastly localised double bonds like cyclopentadiene-1,3 and spiro[2.4]heptadiene- 4,6 and show characteristic correlations with structure parameters.

Chromic acid oxidation of diosgenin acetate yielded 7-ketodiosgeninacetate. Oximation of the ketone followed by Beckmann rearrangement of oxime afforded the title compound.

The major radiation-induced degradation products of 5,6-dihydrothymine (1) in aqueous solutions saturated either with O 2 or N 2 O/O 2 (75/25 v/v) were identified as thymine (10), the trans-and cis-isomers of 6-hydroperoxy-5,6-dihydrothymine (5, 7), 5-hydroperoxy-5,6-dihydrothymine (9), and their corresponding hydroxy derivatives (4, 6, 8). The formation of these compounds is explained in terms of initial H-abstraction from the C(5) and C(6) carbons which gives rise respectively to the transient 5-yl and 6-yl radicals. Thymine hydroxy-hydroperoxides (11-14) and their decomposition products (17-20), which are derived from hydroxyl radical attack at the 5,6-ethylenic bond of thymine (10), were also characterized.

The preparation of 4,4,4-Trichloro-⊿ 2 -l-butenyl-dichlorophosphate and -dichlorophosphite from the corresponding P(V) and P(III) compounds is described.

Osmiumtetroxide and antimony pentachloride form a donor acceptor complex, OsO 4 · 2 SbCl 5 . According to the IR spectrum the complex contains OsOSb bridges. With VCl 4 , TiCl 4 , MOCl 5 and osmiumtetroxide rapid ligand exchange reactions occur, forming VOCl 3 , TiOCl 2 and several oxochlorides of molybdenum and OsCl 4 , respectively.

Impure tungsten nitrido bromide, WNBr 3 (1) is prepared by the reaction of iodine azide with WBr 6 . PPh 4 [WNBr 4 ] (2) can be obtained by the solvent induced decomposition of PPh 4 [WBr 5 N 3 ], which is probably an intermediate in the reaction of WBr 5 with PPh 4 N 3 or in the reaction of PPh 4 [WBr 6 ] with iodine azide. 2 reacts with acetonitrile to form the solvate WNBr 3 · CH 3 CN (3). According to the IR spectra, in all complexes (1-3) W ≡ N triple bonds are present.

A very simple preparation method for the complex [Cl 2 FeS 2 MoS 2 FeCl 2 ] 2- is described and Fe 2+ /MoS 4 2- interactions are discussed. The Resonance Raman Effect is a sensitive probe for the doubly bridging MoS 4 2- ligand.

A series of new ternary intermetallic compounds of the general composition Ca 16 M 18 IB(IIB) -Hg 18 (M = Zn, Cd, Hg, Cu, Ag and Au) has been identified. The X-ray powder diffraction patterns were indexed on a basis of primitive cubic unit cells. From the X-ray data and density measurements it is concluded that these phases belong to the partially disordered (M IB(IIB) and Hg) gamma-brass structure type D8 3 .