Volume 43, Issue 5

The structure of the title compound has been determined by X-ray diffraction. The molecule has C 2 symmetry, containing two dithiaborolanyl groups in twist conformation. The normals of the two BS 3 planes of the molecules form an angle of only 17,6°. All BS bonds can be considered to be single bonds.

The lithium alkoxoamidosilane (Me 2 Si(O t Bu)(N t Bu)Li) 2 (4) and its trimethyltin derivative Me 2 Si(O t Bu)(N t Bu)SnMe 3 (7) have been used, to introduce the ligand Me 2 Si(O t Bu)(N t Bu) = L into molecular compounds of gallium and indium. The following molecules were synthesized: L-M(Me)Cl (M = Ga (5), In (6)), L-InMe 2 (8), L-InX 2 (X = Cl (9), Br (10)), L 2 InX (X = Cl (11), Br (12)) and L 2 Ga 2 Cl 2 (22). The ligand L is assumed to chelate the metal atom on the basis of temperature dependent 1 H NMR spectra. The chelating effect is more pronounced in the gallium derivatives than in the indium analogues. Equilibria between L 2 InX/InX 3 and LInX 2 have been observed in diethylether solutions. No metal(I) derivatives LGa or LIn could be isolated. L 2 Ga 2 Cl 2 (22), formally containing gallium(ll), can be sublimed without decomposition at 110 °C in vacuo.

The X-ray photoelectron spectra of some N,N′-thiobisamines and of two of its complexes with Cr(CO) 5 have been studied. The S(2p) binding energies are found to correlate with the effective nuclear charge on the sulfur atom as well as with the double bond character of the S-N linkage. The effect of the coordination on the N(1s) and S(2p) binding energies agree with sulfur coordination as well as with a π acceptor behaviour characteristic for thiobisamine ligands.

2,4,6-Tri-butylphenylphosphane reacts with CpFe(C 5 H 4 AsCl 2 ) in the presence of DBU to yield CpFe[C 5 H 4 As=PC 6 H 2 (t-Bu) 3 ]. The reaction of this arsaphosphene with (Ph 3 P) 2 PtC 2 H 4 yields , a three-membered ring containing arsenic, phosphorus and platinum.

Cesium hydroxide methanol, CsOH·CH 3 OH, was obtained by recrystallising CsOH·H 2 O in a mixture of liquid ammonia and methanol in sealed quartz ampoules. The colourless, air sensitive crystals are hexagonal (space group P6 3 /m) with a = 1362 pm, c = 430 pm, Z = 6. A structural model derived by Patterson methods was refined to R = 0.033. The structure comprises of trigonal prismatic columns of Cs + and hydrogen bonded chains of OH - and CH 3 OH along the c-axis. This leads to the tricapped prisms filled with Cs + and hydrophobic channels formed by the CH 3 groups.

1,3-Bis(4-ethoxyphenyl)triazenido silver(I) (1) is obtained from equimolar amounts of the triazenido anion and AgNO 3 in THF/CH 3 CN. 1 forms in pyridine the dimer [Ag(EtOC 6 H 4 NNNC 6 H 4 OEt)·py] 2 (2) which crystallizes as yellow pyridine solvate 2·2 py in the monoclinic space group P2 1 /n and a = 1067.1(7), b = 1764.5(9), c = 1373.0(9) pm, β = 106.46(7)°, Z = 2. In the centrosymmetric dimer 2, two triazenido ligands bridge two Ag(I) atoms with their atoms N1 and N3 forming an eight-membered heterocycle Ag 2 N 6 with a short Ag-Ag interaction of 272.6 pm. To each Ag atom an additional pyridine ligand is weakly coordinated with a distance Ag-N40 = 245.5 pm. The bond axis N1 - Ag-N3′ within the heterocycle is not linear (158.5°). The Ag-N distances to the N-atoms of the triazenido ligand are 217.6 and 218.5 pm.

Cs + (tolN 5 tol) - (1) is formed as a yellow crystalline precipitate after addition of a concentrated aqueous solution of CsCl to a concentrated solution of 1,5-Bis(p-tolyl)pentaazadiene(1,4) in ammonia. 1 crystallizes in the orthorhombic space group Pccn with a = 3169(1), b = 434.3(2), c = 1109.4(7) pm, Z = 4. The structure contains (tolN 5 tol) - anions and Cs + cations both occupying two-fold axes. The all-trans N 5 zigzag chain is planar with localized double bonds N1 - N2 and N2′ - N1′ of 127.7 pm and shortened single bonds N2-N3 and N3-N2′ of 136.9 pm. The tolyl substituents are titled by 25.5° against the plane of the N atoms. Cs + is surrounded in a square antiprismatic arrangement by eight N atoms of four N5 chains with distances Cs-N in the range of 314.6 to 366.2 pm.

The reaction of Fe(CO) 4 I 2 with Ag(tolN 5 tol) in THF yields dark violet, oxygen sensitive [Fe(tolN 5 tol) 2 ] 2 (1), whereas in the case of Ru(CO) 4 I 2 the reaction with Ag(tolN 5 tol) occurs under reduction to Ru(I), and brownish, air stable [Ru(CO) 3 (tolN 5 tol)] 2 (2) is obtained. 1 crystallizes from THF as 1·THF in the monoclinic space group P2 1 /c with a = 1395.7(4), b = 2226.5(9), c = 1973.5(7) pm. β = 105.10(2)°, Z = 4. In the binuclear complex four pentaazadienido anions act as (N1,N3)-η 2 , (N5)-η 1 bridging ligands coordinating the Fe atoms octahedrally. 2 forms triclinic crystals with the space group P1̄ and a = 1368.6(6), b = 1393.7(6), c = 1076.1(5) pm, α = 104.59(4)°, β = 107.36(4)°, γ = 73.90(3)°, Z = 2. Two pentaazadienido ligands bridge two Ru(CO) 3 + units with their atoms N1 and N3. In addition, the Ru atoms are connected by a Ru-Ru single bond of 267.5 pm. In 1 as well as in 2 the pentaazadienido ligands exhibit planar N 5 zigzag chains in the all-trans configuration. The N -N-distances are in the range of 124.2 to 137.4 pm.

The reaction of iron(III) acetylacetonate with molten benzoic acid yields Fe(C 6 H 5 COO) 2 (2) besides small amounts of Fe 3 (C 6 H 5 COO) 4 (acac) 2 (1), whereas cobalt(III) acetylacetonate or cobalt(II) carbonate quantitatively yield Co(C 6 H 5 COO) 3 (3). Complex 1 forms triclinic red crystals with the space group PI and the lattice constants a = 1016.0(3) pm, b = 1099.9(2) pm, c = 969.8(2) pm, α = 92.68(2)°, β = 105.67(2)°, γ = 117.57(2)°, Z = 1. 3 is obtained as monoclinic violet needles with the space group C2/c and the lattice constants a = 1739.2(4) pm, b = 1413.8(3) pm, c = 1045.3(3) pm, β = 96.26(2)°, Z = 8. 3 consists of polymeric chains with a zigzag arrangement of the cobalt atoms (Co -Co = 314.5 pm) and an octahedral coordination for Co 1 and (4+2)-coordination for Co2. The benzoato ligands act differently. One benzoate group functions as bridging ligand between adjacent metal atoms, the other acts as a four-dentate ligand by chelating one cobalt atom and bridging its neighbours. Complex 2 was not obtained in form of single crystals, but its properties as well as its IR and Mößbauer spectra suggest a similar structure as for 3. Complex 1 is also polymeric, the chain of iron atoms is nearly linear. The acetylacetonate ligand acts chelating and bridging as a four-dentate ligand, whereas the benzoate anion is only bridging neighbouring Fe atoms. The Fe atoms exhibit octahedral and trigonal bipyramidal coordination.

B(OC 2 H 5 ) 3 reacts with diols to give 2-ethoxy-1,3-dioxa-2-boracycloalkanes (1-4) which, on aceotropic distillation in toluene with amino alcohols, give mixed boric acid esters of the type (5-8, a-g). The structures of these compounds are discussed on the basis of IR and Raman spectra and MS, 1 H, and 11 B NMR data, and with reference to an X-ray investigation published previously. The presence of a boron ← nitrogen coordination is proposed in all cases.

The title compound contains the anions [TeBr 3 Cl 3 ] 2- and [TeBr 4 Cl 2 ] 2- in a 1:1 ratio. The corresponding point symmetries, detected by Raman spectroscopic methods, are 3 m and 4/mmm, respectively. The crystal structure analysis exhibits a random distribution of these anions: K 2 PtCl 6- type, space group Fm3̅m with a = 10.4602(5) Å and Z = 4, final R = 0.036 from 178 F 0 (MoKα).

The reaction of Li 3 P 7 (DME) 3 with crown ether 12-crown-4 and (CHT)Cr(CO) 3 yields a reddish oil, from which red crystals of [Li(12-crown-4) 2 ] 3 P 21 (THF) 2 (1), red crystals of Li 2 P 16 (12-crown-4) x (THF) 2 as well as a not yet identified yellow substance separates. From this mixture crystals of 1 could be isolated. [Li(12-crown-4) 2 ] 3 P 21 (THF) 2 (1) crystallizes in the space group P2 1 /a with a = 3021.1(6) pm, b = 1901.5(4) pm, c = 1603.0(4) pm, β = 95.98(3)° and Z = 4 formula units in the unit cell. The structure is characterized by isolated 1 ∞ [P 21 3- ] trianions and Li(12-crown-4) 2 cations. The trianion has approximately the symmetry mm2. The bond distances d(P-P) range from 213.9 pm to 226.8 pm and are differentiated by their function in the skeleton. The bond angles β(P-P-P) are in the range 86.1° to 107.7° and image clearly the influence of the repulsion of the non-bonded electron pairs of the strained anion. The curvature of the trianion is approx. 0.8 nm -1 and is three times larger than the curvature evaluated from structural models.

The reaction of 1-thia-4,7-diazacyclononane (C 6 H 14 N 2 S = L) with salts containing Tl(I) and (III), In(III) and Pb(II) ions yields 1:1 complexes, which can be crystallized as halide or Perchlorate salts. The structure of [LPb][PbBr 4 ] (5) has been determined: Crystal data: orthorhombic, space group P2 1 2 1 2 1 , a = 853.2(6), b = 1000.1(4), c = 1860(1) pm, Z = 4. Pb 2+ in the [LPb] 2+ cation is seven-coordinated by the tridentate ligand and a square of four Br - ions. The Pb-S distance, 286.0(5) pm, is rather short, the lone pair stereochemically activ. The PbBr 4 - ions are polymeric with octahedrally coordinated lead(II) atoms.

1,1-Bis(trichlorosilyl)ethane, CH 3 CH(SiCl 3 ) 2 (1) is readily available through catalytic hydrosilylation of vinyltrichlorosilane and silicochloroform (90% yield), or through the base-induced reduction of acetyl chloride using again silicochloroform (60%). 1 can be converted into the title compound 2 in 80% yield by lithium aluminium hydride in di-n-butylether. Compound 2 is a highly volatile liquid (bp. 40-42 °C), not spontaneously inflamable in air. which is of interest as a precursor for chemical vapour deposition of hydrogen-containing silicon/carbon alloys (a-Si, C:H) and silicon carbide. Based on thermodynamical data, it is the least stable isomer of the composition C 2 Si 2 H 10 .

Six of ten possible linkage and geometric isomers of the formula [Os(NCSe) n (SeCN) 6-n ] 3- , n = 0-3, have been obtained. The n = 0-2 complexes are prepared from the reactions of K 2 [OsX 6 ] , X = Br, I, and of K 2 [OsO 2 (OH) 4 ] in presence of ascorbic acid, with excess aqueous or methanolic KSeCN solutions at 20-40 °C. By heating the solid tetrabutylammonium salts, N-bonding of the ambident SeCN - is favoured, and the n = 3 species are formed. The complexes are separated by ion exchange chromatography and characterized by vibrational and electronic spectra. Characteristic group frequencies are: ν OsSe : 183 - 216, ν OsN : 224-246, ν CSe(Se) : 508-528, ν CSe(N) : 665-680, ν CN : 2081-2122 cm -1 .

Quantitative analysis by high-pressure liquid chromatography shows that all commercial samples of elemental sulfur besides S 8 contain traces of S 7 (up to 0.56%) and in some cases also S 6 , S 9 , and polymeric sulfur (S ∞ ). Pure S 8 can be obtained by recrystallization from CS 2 . Elemental sulfur minerals also quite often contain traces of S 7 (up to 0.3%). Since neither irradiation by daylight at 20 °C nor heating to 90 °C for 41 days did convert α-S 8 into S 7 , the reactive sulfur molecules S n (n≠8) are believed to origin from liquid or gaseous sulfur which are known to be complex equilibrium mixtures of many S n species. Sulfur melts slowly cooled (within 0.6 to 145 h) from 122 to 20 °C in fact contain S 7 (minimum 0.2%) and at cooling rates of <24 h also other non-S 8 molecules. Solid solutions of S 7 in α-S 8 have also been prepared by cocrystallization of the compounds from CS 2 . In contrast to pure α-S 8 , these solid solutions are pale-yellow at 77 K, and the implications of these findings for the surface composition of Jupiter’s satellite Io and for the mechanical properties of “formed sulfur” (Prills, Rotoform, Slates, etc.) are discussed.

In this paper we report two improved preparation methods for [(CH 3 ) 2 N] 6 W 2 (W≡W) (1), one starting from WCl 4 (yield 51%), and a second one starting from W 2 C 16 (THF) 4 (ca. 60% yield). We have studied the reactions of 1 with different nucleophiles, among them triphenylalkylidenphosphoranes (like Ph 3 P=CH 2 and Ph 3 P=CHPh·LiCl; Ph = phenyl), sulfur and CS 2 . 1 reacts with S 8 and CS 2 in hexane to yield the two new compounds (Me 2 NCS 2 ) 2 WS(S 2 ) (4) and W(CS 2 H)(Me 2 NCS 2 ) 2 (5), both containing dithiocarbamato ligands formed by insertion of CS 2 into the W-N bond. The two mononuclear compounds were characterized spectroscopically, in the case of 4 an X-ray diffraction structure analysis was performed. The reaction of 1 with Se and CS 2 , leads to the compounds 4, (Me 2 NCS 2 ) 2 W 2 S 4 (6) and [(Me 2 N) 2 C]CS 2 (7), which were also characterized spectroscopically. No Se-containing compounds could be isolated. 4 crystallizes monoclinically, C 5 2h -P2 1 /n, with a = 648.6(3), b = 1346.7(6) and c = 1745.9(7) pm, β = 91.85(3)°, V = 1524x10 6 pm 3 , Z = 4. The structure of the seven-coordinate tungsten compound is discussed and compared to complexes with similar ligands and geometry.

The title compounds 4 and 5 were prepared by reaction of 1,4-dimethoxy-2,5-bis(3,4-dimethoxyphenylthio) benzene (8) with sulfur dichloride and selenium dioxide, resp., and characterized by 1 H NMR and MS spectra. An X-ray analysis of 4 shows the compound to have a chair form, i.e. each of its two thianthrene units are folded at their SS axes in such a way that the two peripheral rings are found at different sites of the central ring plane (angles of fold 130.5°). The methoxy groups of the peripheral rings are coplanar, those of the central ring perpendicular to the corresponding ring planes. Bond distances and angles of 4 are in the normal range (CS 177.5 pm, CSC 100.2°).

3,6-Diaryl-1,2-dithiines and their precursors, (Z,Z)-1,4-bis(organylthio)-buta-1,3-dienes, are investigated by 1 H and 13 C NMR spectroscopy. The chemical shifts and coupling constants, which are relevant to the investigated problem, are determined and assigned, respectively, by different techniques (shift increments, spectrum simulation, heteronuclear 2D J-resolved and heteronuclear shift correlated 2D NMR spectra, anomalous off-resonance splittings and selective decoupling experiments). The NMR parameters are discussed in relation to the molecular structure. The 13 C shift values prove the ring structure of 1,2-dithiines and exclude existence of the valence isomer (Z)-but-2-ene-1,4-dithione (absence of thiocarbonyl resonances). The vicinal 1 H, 1 H coupling constants of the C 4 unit of the investigated compounds verify (1) the (Z,Z) configuration of the organylthio groups in 1,4 position of butadiene, (2) the s-transoid conformation of acyclic butadienes and (3) the forced s-cis structure in the cyclic 1,2-dithiines.

The electrochemical synthesis and physico-chemical properties of neutral zinc(II) complexes of bidentate Schiff bases derived from salicylaldehydes are presented together with the X-ray structure of bis[N-(4-methylphenyl)salicylaldiminato]zinc(II). The crystal is monoclinic, a = 21.877(3), b = 8.801(2), c = 12.027(5) Å, β = 96.55(3)°, space group C2/c. The complex is a monomer, and the zinc atom is tetrahedrally coordinated.

The epoxyketone 3 is reduced by borohydride or a Wittig reagent to the oxiranes 6 or 9 respectively, which on acid hydrolysis yield 8a and 8b as derivatives of the title compound 1.

The Separation of the enantiomers of D,L-allo-threoninol, necessary in racemization studies of peptide hydrolysates, gave a surprising result with respect to the elution series of the antipodes. Contrary to the rule (L before D on Chirasil-L-Val) D-allo-threoninol is eluted before its mirror image. This behaviour can only be explained by the differing importance of the asymmetric centres contained in the molecule. As a result of this and taking into account the chromatographic behaviour of allo-compounds refined model concepts of enantiomer separation must be devel-oped in future. The separation of allo-compounds of threonine, isoleucine and cystathionine is considered from this aspect.

DNA decamers containing 2-aminoadenosine were synthesized. Oligonucleotide duplexes including the 2 NH 2 A-T base pairs were prepared and their Tm profile examined. Contrary to expectation, elevation of the Tm value by the 2 NH 2 group is very small in DNA/RNA duplexes. From the CD spectra measurement, we assume that the distortion of the B-DNA structure caused by scattered DNA/RNA base pairing diminishes the efficient hydrogen bonding and base stacking of the duplexes. It was also found that the DNA duplexes containing 2-aminoadenosine hybrids are considerably resistant to ribonuclease T2 or nuclease P1 digestion.

In our search for the antiinflammatory activ principles of fat of badger and alp-marmot, used in folk-medicine as remedies against rheumatism and arthritis, eight known corticosteroids have been detected and identified in the lipophilic fraction of body fats of both animals. Enrichment and detection succeeded by using TLC, straight phase HPLC with diode array equipment, HR-GC on OV-1 capillary columns and GC/MS of the methyloxime-trimethylsilylated steroids. The amount of the detected steroids ranges from 30-40 mg/kg. The whole antiinflammatory activity of the fat, as measured in the rat paw edema test, results from these and further hitherto unidentified cortico-steroids.

[(η 3 -C 4 H 7 )PdCl] 2 reacts with Se(SiMe 3 ) 2 to form [(η 3 -C 4 H 7 ) 6 Pd 6 Se 3 ] (1). 1 has been characterized by X-ray crystal structure analysis. It contains a distorted trigonal prismatic Pd 6 -cluster. Three faces of the Pd-prism are occupied by μ4-Se ligands. 1 crystallizes in the space group Pnma with 4 formula units per unit cell. The lattice constants at 200 K are: a = 1175.1(8), b = 1611.4(12), c = 1720.3(12) pm.

Manganese(III) complexes with 2-[bis(benz-imidazol-2-ylmethyl)amino]ethanol were prepared. Based on the analytical data, IR, magnetic and ESR (“16-line ESR signal” was observed in the frozen state) properties, these complexes are assumed to be of the binuclear structure with μ-oxo and di-μ-acetato bridges.

The IR spectrum of solid Se 4 N 4 has been recorded in the region of 100- 4000 cm -1 . The assignment has been made on the basis of slightly deformed D 2d symmetry, which is in agreement with the X-ray structure determination.