Volume 34, Issue 7

The tert-butyl cation is formed from tert-BuBr in concentrated solutions of AlBr 3 in CH 3 Br, CH 2 Br 2 and CHBr 3 and was characterized by 1 H NMR spectroscopy. Stabilization of the cation depends strongly on the AlBr 3 concentration: in CH 3 Br saturated with AlBr 3 , C(CH 3 ) 3 + is formed in 80% yield; in dilute solutions of AlBr 3 in CH 3 Br the usual de-composition occurs. In saturated solutions of AlBr 3 in CH 2 Br 2 and CHBr 3 the C(CH 3 ) 3 + yield is 60 and 40%, resp. The concentration of the cation decreases in all three solvents by 20 to 30% within 10 days at room temp. In concentrated solutions of AlBr 3 in CH 3 Br the formation of the methyl-tert-butylbromonium ion as a rapidly equilibrating species is suggested. The 1 H NMR chemical shift of C(CHs) 3 + in the presence of AlBr 3 (δ = 5.19 in CHsBr, δ = 5.23 in CH2Br2, δ = 5.35 in CHBr 3 ) indicates strong deshielding in comparison with shifts in SbF 5 and SbF 5 /SO 2

Evidence for the formation of (CH 3 ) 2 Br+ and (CH 3 ) 2 I+ in CH 3 Br and CH 3 I solutions saturated with AlBr 3 comes from the appearance of a second singlet in the 1 H NMR spectrum. The (CH 3 ) 2 Br+ ion is formed at -40 °C to about 5 mol%, the (CH 3 ) 2 I+ ion at -12 °C with 50 mol% yield. At higher temperatures the concentration of the halonium ions decreases rapidly. The (CH 3 ) 2 Br+ ion is not detectable at room temperature, the concentration of (CH 3 ) 2 I+ decreases to about 30 mol%. Dilution of the saturated solutions with methyl halide also reduces the halonium ion concentration. An AlBr 3 /CH 3 Br solution with a molar ratio of 1:3 at -40 °C shows no sign of (CH 3 ) 2 Br+ formation in the XH NMR spectrum. Both effects are best explained by formation of dimethylhalonium ions from the adduct CH 3 X-AIX 3 and by dependence of adduct concentration on temperature and dilution. Exchange of (CH 3 ) 2 Br+ and (CH 3 ) 2 I+ with methyl halide is slow on the NMR time scale at low temperatures similar to the results in SbF 5 /SO 2 . The 1 H NMR singlets of (CH 3 ) 2 Br+ and (CH 3 ) 2 I+ are shifted to lower field by 1.32 and 1.68 ppm in comparison with the chemical shifts in SbF 5 /SO 2 solution

The trimeric chlorotellurate(IV) ion Te 3 Cl 13 - is obtained in benzene solution as a degradation product of cubane-like tetrameric tellurium(IV) chloride Te 4 Cl 6 and can be isolated by crystallization in the form of salts with large cations. The crystal structure of the triphenyl-methyl salt (C 6 H 5 ) 3 CTe 3 Cl 13 (P2 1 /c, a = 1109.5, b = 1644.4, c = 2043.9 pm, β = 114.50°) shows the Te 3 Cl 13 - ion to have approximate C 3V symmetry; as a fragment of the Te 4 Cl 16 cube it consists of three edge-sharing octahedra with a central triply bridging Cl. Bond distances Te-Cl (tripl.br.) 292.4-298.4, Te-Cl (doubl.br.) 270.6-286.3, Te-Cl (term.) 232.0-238.8 pm. The vibrational spectrum of Te 3 C 13 - is discussed.

The o-hydroxyanile of cinnamic aldehyde reacts with methyl, phenyl, oxy-, and aminochlorophosphanes in a combined substitution and oxidative addition to give phosphoranes with the above mentioned bicyclic structure containing phosphorus as bridgehead. For the aminosubstituted species the reaction is followed by a 1.3 proton shift in the C 3 moiety from the cinnamic aldehyde. Whether the bicyclic system occupies meridional of facial positions of the phosphorus trigonal bipyramid is shown to depend on the nature of the phosphorus substituents. An X - ray structure determination of a tricyclic derivative with axial annelation shows the deviation from the ideal trigonal bipyramidal geometry to lie on the Berry pseudorotion pathway

Proton addition to the spirobi(cyclotriphosphazene) anion 1 gives the neutral species 2. An X-ray structure determination shows the proton to be located at a nitrogen atom next t o the spirocenter. The structural consequences of this protonation can be demonstrated by comparisons of intramolecular bond distances and angles and can be understood in terms of structure-determining repulsive N/N interactions in the central PN 4 unit

The 2-hydrido-2-methyl-cyclotri(phosphazene) (1) reacts with perthiophosphonic anhydrides (2) to give cyclotri(phosphazene)diene-2-thiones (3). When 2 contains R ≠ CH 3 , mixtures of CH 3 -3 and R-3 are obtained. This must be due to a competition of sulfur transfer from 2 to 1 and the insertion of a RPS unit from 2 into 1 involving the opening and reclosure of the N 3 P 3 ring. The unusual lability of the cyclotri (phosphazene) ring probably arises from the prototropy in 1

The species R-C 7 H 7 Cr(CO) 3 (R = -CH 2 COCH 3 , -CH(CH 3 )COCH 3 , -CH(CH)CH 3 ) 2 COCH 3 ) have been synthesized by reaction of [η 7 -C 7 H 7 Cr(CO) 3 ][BF 4 ] with suitable ketones in the presence of bases like OH- and F- , suggesting a nucleophilic addition of the enolate ion to the cycloheptatrienyl ligand. 1 H NMR spectra revealed the CH 3 -CO-CH(CH 3 ) group being bonded to the cycloheptatriene ligand via the a-carbon atom of the ethyl group

The new compounds BaMn 2 Sb 2 , BaZn 2 Sb 2 and BaCd 2 Sb 2 have been prepared and structurally characterized. The crystallographic data are: BaMn 2 Sb 2 : I4/mmm, a = 441.8 ± 0.6 pm, c = 1440 ± 2 pm, ThCr 2 Si 2 structure, BaZn 2 Sb 2 : Pnma, a = 1053.9 ± 0.8 pm, b = 450.2 ± 0.2 pm, c = 1163.9 ± 0.8 pm, BaCu 2 S 2 structure, BaCd 2 Sb 2 : P3̅m 1 , a = 477 ± 1 pm, c = 808 ± 2 pm, Ce 2 O 2 S structure

Tetrakis(trimethylsilyl)distibane, (Me 3 Si) 4 Sb 2 is produced by reaction of tris(trimethylsilyl) stibine, (Me 3 Si) 3 Sb, with three or less than three equivalents of t-butyl iodide, with trimethyliodosilane, Me 3 SiI and iodine. The reaction of (Me 3 Si) 3 Sb with three or more equivalents of i-butyl iodide and methyl iodide also yields tri-t-butylstibine, trimethylstibine and Me 3 SiI

The synthesis of dinuclear complexes of the types [(CO)4FeSiR 1 R 2 ]2 and Fe2(CO)7(SiR 1 R 2)2 is described. IR, mass and Mössbauer spectroscopic data are discussed.

The hitherto unreported compound NH 4 CrF 4 could be prepared by applying hydrothermal high pressure techniques. X-ray powder data show NH 4 CrF 4 to crystallize tetragonally with a = 743.2, c = 650.4 pm, similar to CsFeF 4 and other TIAIF 4 -related structures. The magnetic behaviour was studied below room temperature and proved NH 4 CrF 4 to become antiferromagnetic (TN = 34 K ) within the range known from other A I CrF 4 compounds. The thermolysis of NH 4 CrF 4 , as investigated by X-rays and TG/DTA, begins at about 400 °C and yields CrF 3 and also Cr 2 F 5 , if extended to 1000 °C

The mixed Sn(II)/Pb(II) compounds of the type CH 3 NH 3 [PbwSn 1-n X 3 ] (X=Cl, Br, I) have the cubic perovskite structure which is established by X-ray powder data and 119 Sn Mössbauer spectroscopy. With exception of the chloro system the coloured compounds show electrical conductivity which increases with increasing Sn(II) content. Their physical properties can be interpreted by means of a "p-resonance bonding". Replacement of Sn(II) by Pb(II) and I by Br and Cl decreases this bonding effect, which is produced by the interaction of filled X p-orbitals with empty p-orbitals of Sn(II) or Pb(II). The synthesis is described

Tungsten nitride chloride-POCl 3 solvate, [WNCl 3 • POCl 3 ] 4 • 2 POCl 3 is prepared by the reaction of WNCI 3 with excess POCI 3 . With equimolar amounts of POCI 3 in dichloromethane suspension the complex [WNCI 3 • POCl 3 ] 4 • 2 CH 2 CI 2 is formed, which is easily decomposed leaving pure [WNCI 3 • POCl 3 ] 4 . The IR spectra of these complexes were recorded and assigned. A new preparative route to WNCI3 from tungsten hexachloride and iodine azide is described. [WNCI 3 • POCl 3 ] 4 • 2 POCl 3 crystallizes in the triclinic space group P1̅ with two tetrameric units per unit cell. The crystal structure was solved by X-ray diffraction methods (Å = 0,087; 3085 observed reflexions). The structure consists of planar and almost square W 4 N 4 -eight-membered rings with alternating W-N bond lengths. The distorted octahedral environment of the tungsten atoms is completed by three terminal Cl-ligands and by the oxygen atom of a POCI 3 molecule, which is coordinated trans to the W = N triple bond. The two additional POCI 3 molecules are weakly linked to two of the four POCI 3 solvate molecules, giving rise to an increase of the W-O bond lengths to these donor groups

Some bis(η 5 -methylcyclopentadienyl) N-aryl-dithiocarbamato chloro titanium(IV) compounds of the general formula η 5 -(Mecp) 2 Ti(S 2 CNRH)Cl (R = phenyl; o-, m- and p-tolyl; p-methoxy phenyl; o- and p-ethoxy phenyl; o-, m- and p-chlorophenyl; p-bromophenyl and p-iodophenyl groups) have been prepared by the reaction of bis(η 5 -methylcyclopentadienyl) titanium(IV) dichloride with ammonium N-aryl-dithiocarbamates. A study of the molecular weight, conductance, infrared and electronic spectra, and magnetic susceptibility in addition to elemental analysis has been carried out to throw some light on the probable structure of these derivatives

Rb 2 AgAu 3 I 8 can be prepared in the presence of ether by the reaction of stoichiometric amounts of RbI, AgNO 3 and Au with an excess of I 2 and concentrated HI. It crystallizes monoclinic in the space group C 2/c. The structure consists of Rb+, Ag+, AuI 2 - and AuI 4 ions. Short distances of 304 pm between the gold(I) atoms can be interpreted by weak bonding interactions. Rb 2 AgAu 3 Is shows a very close structural relationship to Rb 3 Au 3 Is. The substitution of one third of the Rb+ ions by Ag+ leads only to small changes in the structure, which generate a suitable tetrahedral coordination for the Ag+ ions. The result of the structure determination supports the assumption that the monovalent gold prefers a linear coordination and covalent bonds, whereas silver tends to a more ionic character and higher coordination numbers

Na 2 S 2 CO 3 crystallizes in 4 modifications. The familiar monoclinic a-form stable at ambient temperature transforms into the trigonal β-form at 330 °C which at 388 °C converts to b ccy-Na 2 S 2 O 3 . These transformations are reversible. Unstable orthorhombic α'-Na 2 S 2 CO 3 (Pna2 1 ) is obtained by dehydration of the pentahydrate or by cooling the β-phase. The γ-phase decomposes in sealed ampoule to Na 2 SCO 4 and NaS 5 ; decomposition is slow below and rapid above 440 °C. Equilibrium displacement by distillation of sulphur accelerates decomposition even for β-Na 2 S 2 O 3 , and maintaining low sulphur pressure by pumping gives Na 2 SO 3 . β- and γ-Na 2 S 2 CO 3 are superionic conductors; a dynamic model is presented for the β-structure with Na + conduction pathways originating from oscillation of the S 2 O 3 2- tetrahedra. Structural relationships can be derived with respect to the arrangement of the thiosulphate groups.

The reaction of trimethylsilylsulfonamides with halodiorganylboranes leads to the corresponding sulfonamidoboranes and halotrimethylsilane. Trimethylsilylsulfonamides are prepared by reaction of the corresponding sulfonyl chlorides with primary amines, followed by the addition of chlorotrimethylsilane in the presence of excess triethylamine. 1 H, 11 B NMR spectra and mass spectra are reported

The reaction of l,l,l-tris(diiodarsinomethyl)ethane, CH3C(CH2Asl2)3 (1), with H2O, H2S and CH3NH2 in THF gives the adamantane cage compounds CH3C(CH2ASO)3 (4), CH3C(CH2ASS)3 (5) and CH3C(CH2ASNCH3)3 (6) in high yields. The crystal structure of 5 has been determinated by X-ray diffraction. The unit cell (space group P2i/w) contains 4 isolated molecules in a cubic closest packing. The heteroadamantane 5 has an enlarged cage structure with extremely spread C-C(H2)-As bond angles of 124° at the methylene carbon atoms. Some pharmacological properties of the adamantane derivatives 4 and 5 have been studied. All compounds have been characterized by mass spectrometry and infrared, Raman and X H NMR spectroscopy.

Zolon Red, Mercury(II) The extraction of mercury(II) from the aqueous solutions of mercury(II) nitrate and mercury(II) chloride with zolon red (HZR) dissolved in w-butanol has been studied. The extraction of mercury (II) from the aqueous nitrate system has been found to be much better compared to that from the aqueous chloride system in the pH range of 1 to 6. The extraction of mercury with zolon red is simple, fast and selective. The composition of the extracted mercury zolon red compound has also been studied. Regeneration of the extracting solution of zolon red is readily achieved by stripping the mercury(II) with an aqueous cyanide solution.

The partially oxidized form of Magnus' salt has been studied by resonance Raman spectroscopy (RRS) and it has been established that the oxidized form is a chlorine bridged chain polymer. The spectra show intense progressions, υν, where ν, is the symmetric ···X-Pt(IV)-X··· stretching mode, and v the quantum number

A series of copper and nickel biuret complexes has been studied by X-ray photoelectron spectroscopy (XPS). The results include one of the first reports of the XPS spectrum of a copper(III) complex. Significantly, this diamagnetic complex exhibits intense satellite structure in both the Cu 2P3/2 and Cu 2Pi/2 regions. The isoelectronic nickel(II) complex shows no comparable satellite structure.

During UV irradiation of nitrobenzene and some derivatives in benzene solution biphenyls are formed as in the case of the corresponding iodobenzenes. Using fluorobenzene as a solvent, isomeric fluorobiphenyls (o, m, p) will be found as reaction products having a definite distribution (o >m > p), which is characteristic for substitution by radicals. Therefore, we conclude that the CN-bond is split homolytically. Besides the biphenyls, other important reaction products of the aromatic nitro compounds - phenols and nitrophenols - are identified

Tris(ethylthio)borane (1) is a convenient donor for ethanthiol, esp. for the ketalization of carbonyl compounds. With amides, amide thioacetals are obtained

The photolysis of twelve aromatic ethers in solution has been studied by CIDNP and product analysis. The primary step is the scission of the C-O bond in the excited singlet state. The partners of the resulting radical pair (Ph-O' and R 1 ) undergo three major reactions: (i) geminate recombination and out-of-cage combination resulting in the reformation of the starting material, (ii) geminate recombination and out-of-cage combination resulting in cyclohexa-2,5- dienones and cyclohexa-2,4-dienones which are isomers of the starting material, (iii) H-abstraction from the solvent by the more reactive ones of the two radicals (mainly RO") and combination of the less reactive ones {e.g. benzyl) in the bulk solution. The quantum yield of photodecomposition is low for diphenyl ether ( Ø ~ 0.002) but approaches unity (0.3-0.9) in benzyl aryl ethers where the benzyl-oxygen bond is cleaved. If the aroxyl radicals are substituted in ortho (para) position the resulting ortho (para)- disubstituted cyclohexadienones are stable. Otherwise they swiftly rearrange into the phenols. The cyclohexa-2,4-dienones which are the precursors of the ortho-substituted phenols isomerize faster than the cyclohexa-2,5-dienones that give the para-substituted phenols. The rates of these rearrangement reactions are enhanced by acid catalysis

Synthesis of isoponcimarin, 7-(3'-methyl-2',3'-epoxy-butiloxy)-8-(3"-methyl-2"-oxobutyl) coumarin, a natural coumarin isolated from Poncirus trifoliata L., was obtained starting from acetyl osthenol. From the intermediate 7-acetoxy-8-(3'-methyl-2'-oxobutyl) coumarin, the coumarin derivatives isomeranzin and dihydrooroselone were also prepared

cts-Dichlorodiammine platinum(II), which is known to be an active anticancer compound, and tryptophan form paramagnetic complexes in aqueous solution. These can be detected by means of electron spin resonance spectroscopy (ESR) after a reaction time of several hours. The ESR spectra are interpreted to be due to Pt(III) in a low spin d7 configuration. The optical results obtained are in accordance with the assumption of columnar structures of the paramagnetic complexes

3-Pyridinecarboximidamide gave with alkylating agents quaternary salts (2), that rearrange on addition of anionic base to 2-amino-pyridinecarbaldehyde (3). Derivatives of 3 can be obtained by reaction of 3-cyano-pyridinium salts with primary amine on addition of anionic bases

The glycosidic component of cinerubin A, an anthracycline antibiotic, has been replaced by a polyoxyethylene (POE) chain. The resulting POE-bound e-pyrromycinone was readily soluble in water and exhibited full biological activity

The structural requirements for the regioselective photochemical ring-opening of chlorin derivatives and the corresponding rate of formation of the pertinent photobilins are reported. The structure of one of the photobilins is verified by X-ray analysis.

The syntheses of the new compounds dimethylpentathiane, cyclohexylidenepentathiane, dibenzylpentathiane, 1,2,3,5,6,7-hexathiocane, 4,8 -dimethyl-1,2,3,5,6,7 -hexathiocane and bis (cyclohexylidene) -1,2,3,5,6,7 -hexathi - ocane are described. The main mass spectral fragmentation paths are given for both classes of compounds

Two new intermetallic compounds K 3 Ag 3 As 2 and K 3 Cu 3 As 2 have been prepared and their crystal structures determined. They crystallize in the rhombohedral space group R3̅m with K 3 Cu 3 As 2 : a = 576(2) pm, c = 2026(5) pm, K 3 Ag 3 As 2 : a = 599(2) pm, c = 2135(4) pm. and are isotypic to K 3 Cu 3 P 2

A low temperature (-110°C) X-ray structural analysis of PCI 3 yielded the bond distances P-Cl = 203.43(12) and 201.86(23) pm and bond angles Cl-P-Cl = 100.04(7)° and 100.19(7)°. The shortest intermolecular contacts P ··· Cl and Cl ···C1 are in the range of the sum of van der Waals-radii

Methylbismuth-bis(diethyldithiocarbamate), X-ray The crystal structure of the title compound, recrystallized from ethanol, was solved by means of X-ray diffraction methods and could be refined to an i?-value of 0.050 with 2126 reflections observed. In contrast to its behaviour in benzene solution, where the compound is monomeric, in the crystalline state dimeric units are formed by intermolecular Bi-S-interactions. The bismuth atoms are coordinated in form of a slightly distorted pentagonal pyramid with the free electron pair presumably directed opposite the apical C-atom.

ReO 3 Cl with AICI 3 and NbCls, respectively, forms the donor acceptor complexes AlCl 3 · ReO 3 Cl and NbCl 5 • ReO 3 Cl. According to their IR spectra the complexes contain Re = O-Metal bridges. GaCl 3 also forms a weak donor acceptor complex with ReO 3 Cl, which catalyzes the reaction of ReO 3 Cl with CCl 4 forming COCl 2

Perthiophosphonic anhydrides (1) and phos-phorus(V) sulfide react with benzo-phenylhydra-zonoyl chloride (2) eliminating HCl and yielding the title compounds 3 and 4, which formally are cycloadducts of the monomeric units RPS 2 and P 2 S 5 , respectively, and diphenyl nitrilimine. The corresponding cycloreversion is observed in their mass spectra.

Using a strongly acidic cation exchanger resin, the dependence of the calcium isotope separation on the HNO 3 eluant concentration is investigated on column experiments. The elementary separation effect of the isotope ratios 44 Ca/ 40 Ca and 48 Ca/ 40 Ca is determined. Up to HNO 3 concentrations of about 1.5 M the lighter calcium isotopes are enriched in the resin phase, whereas, using more concentrated HNO 3 solutions, the heavier isotopes are enriched in the ion exchanger. A comparison of these results with those using hydrochloric acid and perchloric acid show, that there is a strong dependence of the isotope separation on the concentration and the counter ion of the eluant solution