Volume 33, Issue 8

The new compound Li 5 Na 2 Sn 4 crystallizes trigonally, a = 472.3 ± 1 pm, c = 7178 ± 8 pm, space group R3̅m-D 5 3d . A quarter of the Sn atoms in the unit cell build up a puck­ered net of six-membered rings, another quarter is bound to the net-atoms forming a tetrahedral Sn coordination. The other half of the Sn atoms is ordered in layers of parallel Sn 2 pairs. The nets and layers are separated by the alkali atoms. The structural relations to the variants of the W-structure type of compounds in the system Li-Sn and Na-Sn are shown.

β-NaSbS 2 crystallizes monoclinically, C2/m, with a = 1284(2) pm, b = 582.5(8) pm, c = 581.3(3) pm, β - 118.74(7)°. In the structure there are ψ-SbS 5 -octahedra, which are connected by common edges to sheets separated by the Na ions.

CaAl 2 Se 4 and SrAl 2 Se 4 have been prepared and their crystal structures determined. They crystallize orthorhombically, space group Cccm, with the lattice constants: CaAl 2 Se 4 : a = 633 ± 1pm, b = 1048 ± 1pm, c = 1053 ± 1pm; SrAl 2 Se 4 : a = 627 ± 1 pm, b = 1082 ± 1 pm, c = 1085 ± 1 pm. The structures of these compounds are closely related both to each other and to the TlSe-structure.

(Pentane-2,4-dionato)-tetrafluorophosphorane crystallises in the space group P2 1 /c, Z = 8, with a = 8.896(2), b = 13.760(4), c = 13.316(2) Å, β = 93.42(3)°. The structure was refined to R = 0.053 for 2445 reflections. Small but significant differences are observed in the bond angles at phosphorus and in the chelate ring conformations of the two indepen­dent molecules. These display an approximate mirror plane perpendicular to the chelate rings, which are in the boat form with P and C(3) displaced from the plane of the remaining ring atoms. The average P-O distance of 1.719(2) Å is similar to that for a σ-bond. 19 F and 31 P NMR and mass spectral data are reported. The basis peak is formed by the cleavage of the two P-0 bonds resulting in the ion PF4 + (m/e 107).

Oxidation of 5,10-dihydro-5,10-dimethylphenazine and 5,10-dihydro-5,10-diethyl-phenazine under different reaction conditions leads to several iodine containing solids. The preparation and X-ray structure of two of them, 5,10-dihydro-5,10-dimethyl-phcnaziniumtriiodide (3) and 5,10-dihydro-5,10-diethylphenaziniumtriiodido (4) are reported here. Compound 3 crystallizes in space group P2 1 /n with lattice parameters a = 8.552(6) Å, b= 16.953(2) Å, c- 12.157(9) Å and β= 103.46(2)° with four formula units in the unit cell. The structure was refined to an R-value of 0.046 using 2387 independent reflections. The lattice constains distinct, slightly distorted triiodide ions and bent 5,10-dihydro-5,10-dimethylphenazinium radical cations. Compound 4 crystallizes in the same space group P2 1 /n with lattice parameters a = 8.531(6) Å, b = 8.332(21) Å, c = 13.320(15) Å and β= 94.44(19)° with two formula units in the unit cell. The structure was refined to an R-value of 0.076 using 1195 independent reflections. The lattice contains strictly linear symmetrical triiodide ions and planar centrosymmetrical 5,10-dihydro-5,10-diethyl- phenazinium radical cations.

The reaction of bis(diphenylglyoximato)platinum(IV) diiodide with AgClO 4 in benzene yields red brown needles of the compound bis(diphenylglyoximato)platinum(III) perchlorate (A) and crystals of bis(diphenylglyoximato)platinum(III) perchlorate which contains additionally between one and one and a half moles of benzene per formula unit (B). Both compounds are highly hygroscopic and instantaneously change their color to black-green in a humid atmosphere. Crystals of A are tetragonal, a = 20.325(2), c - 6.519(4) Å, space group D 8 4h -P4/ncc, Z = 4. The structure consists of stacks of [Pt(dpg) 2 ] + cations with equidistant Pt-Pt separations of 3.259(4) Å. The Perchlorate ions are disordered in channels formed by the cation columns. Crystals of B are triclinic, a = 14.29(3), b = 13.54(2), c -10.34(3) Å, a = 85.2(2), β = 113.2(2), γ = 93.9(2)°.

The halogenated acylphosphines RC(O)PPh 2 (1a-f) [R = ClCH 2 (a), FCH 2 (b), F 2 CH (c), C 2 F 5 (d), C 3 F 7 (e), C 6 F 5 (f)], which can be oxidized by rigorously dried oxygen to the phos­phine oxides RC(O)P(O)Ph 2 (2a-f), are obtained by reaction of NaPPh 2 with the acyl chlorides RC(O)Cl. From 2a-f and stoichiometric amounts of water the alcohols RC[Ph 2 P(O)] 2 OH (3a-f) are formed. While 3c-f are isomerized into the phosphinates RC[Ph 2 P(O)][OP(O)Ph 2 ]H (4c-f), the alcohols 3a, b are stable. The hydrolytic and thermal behavior of the phosphine oxides 2 and the alcohols 3 are discussed regarding the nature of the acyl residue.

1-Organyl-1-boracyclopentanes react with alkynyltrimethylstannanes to give 1-bora-cyclohexylid(2)enes as the only products. The analogous reaction with methylbis (tert-butyl)borane leads to a nonstatistical distribution of organoboration products. Structure and stereochemistry of the new compounds are discussed on the basis of methanolysis reactions and 1 H, 11 B and 13 C NMR data.

CH 3 NH 3 SnBr x l 3-x : (x = 0-3) has the cubic perovskite structure with the unit cell parameters a = 5.89 Å (x = 3), a = 6.01 Å (x = 2) and a = 6.24 A (x = 0) and Z = 1. The compounds show intense colour and conducting property. The 119 Sn Mössbauer data are consistent with the high symmetry environment of the Sn(II)-ion. A bonding model, using a “p-resonance-bonding”, can explain the properties of the cubic system. The synthesis is described.

A single crystal of Ag 8 GeTe 6 was found to be rhombohedral, pseudocubic, space group R3m, with a = 817.6 pm, a = 60° and Z= 1. The anion lattice consists of three-dimen­sionally connected Frank-Kasper polyhedra with C. N. 12 and 16. The structure comprises isolated GeTe 4 -tetrahedra and silver ions, statistically distributed over a number of sites with distorted tetrahedral, trigonal and linear co-ordination. Structural data for some other compounds of the argyrodite family are given.

The conversion of calcium phosphate into calcium diphosphate through cyanate in an aqueous suspension, discovered by Miller and Parris [1], has been reinvestigated thor-oughly. The reaction is initiated through the disproportionation of calcium hydrogen phosphate to give hydroxylapatite and calcium dihydrogen phosphate, which reacts with cyanate via carbamoylphosphate to yield calcium diphosphate and urea. In particular, it could be shown that the process of phosphate condensation may also be initiated when cyanate is generated by a photochemical oxidation of hydrocyanic acid. -The importance of this reaction with respect to the prebiotic synthesis of biopolymers is discussed.

The hexagonally crystallizing compounds MgFe 6 Ge 6 and LiCo 6 Ge 6 were prepared and structurally characterized by single crystal investigations. The lattice constants are a = 506.7 pm, c = 804.5 pm, c/a= 1.58s for MgFe6Ge6 and a = 504.8 pm, c = 772.9 pm, c/a = 1.531 for LiCo 6 Ge 6 . The structures (space group P6/mmm) are closely related to the structure of LiFe 6 Ge 6 and the B 35-type structure of FeGe.

By the weak acid interaction of polymeric phosphanes the condensation of ethylendi-amine yields in a small amount bicyclo-[4,4,0]-1,4,6,9-tetraazadecane C 6 H 14 N 4 . The compound crystallizes triclinic in the space group P1̅ with a = 841.6 pm, b - 463.6 pm, c = 529.2 pm, a= 109.05°, β= 108.35°, γ = 84.13° and Z= 1 formula unit per unit cell. The two condensed six-membered rings have chair conformations. The mean N-C bond lengths are 146.0 pm, the bridging C-C bond is 150.3 pm, whereas the other C-C bonds are 155.1 pm. Structure and condensation reaction are discussed.

A simple, quick and reliable method is derived to calculate values of [(O,F)/Me] for block structures. The method of calculation is exemplified using ideal and real (defect) block structures and inconsistent published data. The method represents a simple means to systematically classify block structures.

The reaction of trimethylsilylamidines with 2-chloro-1,3,4,5,6-pentamethylborazine leads to the corresponding amidinoborazines and chlorotrimethylsilane. 1 H, 11 B, 11 F NMR spectra, mass spectra and characteristic IR group frequencies are reported.

The first Re NQR spectra of rhenium oxygen compounds with rhenium atoms in the pseudo-octahedral environment of Re 2 O 7 (H 2 O) 2 and Re 2 O 7 (H 2 O) 2 · 2(1,4)-dioxane were found. The values of the Re NQR coupling constants of these rhenium atoms are the highest measured until now. They show, that the gradient of the electrical field is much more sensitive to distortions of an octahedral crystal field than to distortions of a tetrahedral field.

The reaction of ASCl 3 with the transition metal anions [η 5 -C 5 H 5 (CO) 3 M] ⊖ (M = Cr, Mo, W) yields the arsenic transition metal complexes η 5 -C 5 H 5 (CO) 3 M-AsCl 2 , which readily form trans-η 5 -C 5 H 5 (CO) 2 LM-AsCl 2 in the presence of phosphorus donors [L = P(OCH 3 ) 3 , P(CH3)2C 6 H 5 ]. Addition of M(CO) 5 -groups on the trivalent arsenic occurs with THF · M′(CO) 5 (M′ = Cr, Mo) leading to the arsenic bridged dinuclear complexes η 5 -C 5 H 5 (CO) 3 Cr-AsCl 2 -M′(CO) 5. Controlled Cl/F-exchange at the bridged species can be achieved by use of AgBF 4 .

Substitution of an acetylacetonate by a carboxylate in the neutral (acac) 2 Cu(II) was achieved by its reaction with tri- and dichloroacetic acid in benzene (HCO 2 R where R = CCl 3 or CHCl 2 ; Hacac = acetylacctone) which led to the formation of the mixed chelate square planar complex (acac)Cu(OCOR). The later complex, R = CCl 3 , reacted with heterocyclic bases to produce the square pyramidal complexes (acac)Cu(OCOR) (base), (base = 2- methylpyridine or quinoline); with ethylenediamine (en) to give the octahedral [(en) 2 Cu(OCOR)]Cl, and with methanol and piperidine or boiling methanol alone to give the methoxo-bridged (acac)Cu(OCH 3 ) 2 Cu(acac). The reaction of acetylacetonate-carboxy- late-copper(II) complex (R = CHCl 2 ) with heterocyclic bases led to the cleavage of the acetylacetonate ligand and the formation of the octahedral Cu(OCOCHCl 2 ) · 2 base (base = pyridine, 2-, 3- or 4-methylpyridine). The same cleavage reaction took place, and also with R = CCl 3 , in their reaction with 8-hydroxyquinoline to form the mixed chelates (ROCO)Cu(Oxinate). These formulations are based on chemical analyses, electronic and vibrational spectra, and on conductance measurements.

Low temperature photolysis of (η 5 -C 5 H 5 )Co(CO) 2 with diphenyldiazomethane in tetrahydrofurane yields μ-carbonyl-μ-diphenylmethylene-bis(η 5 cyclopentadienylcobalt) (Co-Co) and μ 3 -earbonyl-μ 3 -(diphenylmethylenehydrazido)(N.N.N)-cyclotris(η 5 -cyclo-pentadienylcobalt) (3 Co-Co). The bridged μ-diphenylmethylene complex is also formed by thermal reaction of (η 5 -C 5 H 5 )Co(CO) 2 with diphenyldiazomethane in boiling benzene.

Technical Toxaphene can be separated in two fractions by recrystallisation which are investigated with the help of GC/MS and toxicological methods. Especially the Retro-Diels-Alder-fragmentations give specific informations on the structure of highly chlorinated bornane derivatives representing the main components of the technical mixture. For this study lower chlorinated bornanes are used as model substances. Toxicological investigations show that both fractions have lower activity than technical toxaphene.

The (Z,Z,Z)-configuration of the mono-lactim-ether of an alkyl substituted bilatriene-abc, Etiobiliverdin-IV-γ, was established for chloroform solutions. Moreover the conformation of this molecule is a helical one (syn-syn-syn) with a twist along the single bonds at the methine groups of approximately 20°. The two tautomeric lactam-forms with a proton on one or the other nitrogen atom of the pyrromethene subsystem are indistin-guishable by the methods used in this investigation: 1 H NMR pattern, Lanthanide induced shift technique and Nuclear Overhauser Effect measurements.

Four-bond proton-proton coupling constants in allenes are reported. The substituent effects on the coupling constants are discussed on the basis of the dual-substituent parameter approach. Furthermore, the coupling constants are related to quantum-chemical indices (electron densities, overlap populations) obtained from semiempirical CNDO/S and ab initio STO-3G calculations. The magnitudes of the coupling constants depend upon the polar natures of the substituents as well as upon their charge-transfer abilities (resonance effects) to a com-parable amount. In general, the coupling constants in 1,3-disubstituted allenes are nonadditive in ligand -specific parameters.

5-Arylazo-2-thiohydantoin derivatives (2a,c) were cleaved and rearranged by aqueous sodium hydroxide to give the corresponding 1-aryl-⊿ 2 -1,2,4-trazole-5-imino-3-carboxylic acids (3a-c). 3 a was decarboxylated to 1-phenyl-⊿ 2 -1,2,4-triazoline-5-imine (5). Hydrolysis of 5-arylazo-1-phenyl-2-thiohydantoins (6a-c) behaved in different manner affording 1-aryl-4-phenyl-⊿ 2 -1,2,4-triazoline-5-thione-3-carboxylic acids (7a-c). Fusing (2a-c) with aromatic amines at high temperature gave the corresponding anilides (8a-h). Treatment of 5-arylidene-2-thiohydantoin derivatives (9a-c) with hydrazine hydrate gave colourless products of thioureido cinnamic acid hydrazide derivatives (10a-c), while refluxing 5-arylidene-2-methylmercaptohydantoin (11a-d) with hydrazine hydrate and/or benzo-phenone hydrazone gave the corresponding glycocyamidine derivatives (12a-g).

The main products of the 185 nm photolysis of neat liquid tetrahydropyran are pent-4-en-l-ol (7) (∅ = 0.40), 2-(5′-hydroxypentyl)tetrahydropyran (10) (0.21), valeraldehyde (6) (0.13), and pentan-1-ol (8) (0.08). These products are thought to be formed via the biradical ·O(CH 2 ) 4 ĊH 2 and/or through intramolecular (6, 7, 8) and intermolecular (10) photoreactions. In the case of 10, the probability of a specific intermolecular photoreaction involving two tetrahydropyran molecules is suggested by the fact that in the photolysis of solutions of tetrahydropyran in cyclohexane and formaldehyde dimethyl acetal products analogous to 10 made up of a tetrahydropyran and a solvent molecule moiety, are not formed.

The synthesis of hydroxy-xanthone-3-O-β-glycosides by condensation of the appropriate aglycone and the acetyl-α-D-glycosyl bromide in pyridine solution in presence of silver carbonate is described. The naturally occurring l-hydroxy-3-O-β-primeverosyl-7-methoxy xanthone (gentioside) has been synthesized and its structure thereby confirmed.

In the reaction of lithio-aminofluorosilanes with trimethylsilylisocyanate or trimethylsilylthionylimide LiF is eliminated and carbodiimides and sulfurdiimides are formed, respectively.

Black hexagonal platelets growing on strontiumoxide in the presence of chromium (III)-oxide and air at temperatures from 1250 to 1400 °C have been shown to belong to the rhombohedral space group R3̅m. In hexagonal orientation the elementary cell has the axes a 0 = 1115.8 ± 0.9 pm and c 0 = 4037 ± 3,6 pm and Z = 24, D x =4.26. Structurally the compound is closely related to Ba 3 (PO 4 ) 2 , with the exception, that there are defects in the metal sub-lattice. At temperatures below 1200 °C Strontiumchromate(V, VI) decomposes into the dis-crete chromates(V) and -(VI). At temperatures from 113 to 338 K the compound is an electronic semiconductor with an activation energy of 0.26 eV.

Equimolar mixtures of Sr 3 (PO 4 ) 2 and SrCrO 4 form two high-temperature compounds with different ranges of thermal stability. A rhombo-hedral defect-bariumphosphate structure with hexagonal axes a o - 1091 pm and c0 = 3978 pm is stable at 800-1100 °C. At higher temperatures (1200-1400 °C) it changes reversibly to a cubic Eulytite-type structure with a o = 1031 pm. At room temperature both modifications are meta-stable. The thermal stability of the rhombo-hedral form is raised by minute concentrations of gaseous chromium oxides or by partially ex-changing phosphate by chromate(V). With more than 6 mole% of Sr substituted by Ba, the cubic modification only can be obtained.

A cubic polymorph (SrSi2 type of structure) is obtained if orthorhombic (BaSi2 type of structure) Sro.5Bao.5Si2 is treated in a belt type apparatus (40 kbar, 1000 °C): P4332 (or P4i32), Z = 4, a = 662.2 pm, xSi = 0.419.