Volume 59, Issue 3

The binary transition metal magnesium compounds RhMg 3 and Ir 3 Mg 13 have been synthesized from the elements in sealed niobium tubes and investigated on the basis of X-ray powder and single crystal data: Cu 3 P type, P6 3 cm, a = 790.5(4), c = 825.6(3) pm, wR2 = 0.0244, 344 F 2 values, 27 variable parameters for RhMg 3 , and R3̅c, a = 1607.0(2), c = 844.88(9) pm, wR2 = 0.0535, 656 F2 values, 29 variable parameters for Ir 3 Mg 13 . The rhodium atoms in RhMg 3 have coordination number 11. These polyhedra show an AB AB stacking sequence like in the hexagonal close-packed structure. The crystal chemical relation of the Cu 3 P type structure of RhMg 3 with the aristotype Na 3 As (IrAl 3 ) is discussed on the basis of a group-subgroup scheme. Ir 3 Mg 13 crystallizes with a new complex structure type with coordination numbers of 11, 14, 15, 14, and 12 for the Ir, Mg1, Mg2, Mg3, and Mg4 atoms, respectively

Single crystals of bismuth orthoborate, BiBO 3 , were grown from the melt in the system Li 2 OBi 2 O 3 - B 2 O 3 · BiBO 3 is confirmed to adopt at least two different structural modifications. The modification BiBO 3 (I) (corresponding to PDF Nr. 28-0169) crystallizes with space group P2 1 /c. The structure consists of [Bi 2 O 10 ] groups that are formed by two edge-sharing distorted [BiO 6 ] octahedra and that are interconnected by sharing common corners (oxygen). The [Bi 2 O 10 ] groups are further sharing corners with planar [BO 3 ] groups giving a three-dimensional framework

High-yield syntheses of the bromide (1a) and picrate salts (1b) of the 5-azonia-spiro[4]nonane cation [(CH 2 ) 4 N(CH 2 ) 4 ] + are reported. In the single crystal X-ray diffraction analyses of the two salts the spirocyclic quaternary ammonium cations have their five-membered rings in envelop and twist conformations modified by packing forces. The conformation found experimentally for 1a has C2-symmetry as predicted for the gas phase by quantum-chemical calculations (RI-DFT, RI-MP2), but the five-membered rings are intermediate between the expected envelop and the twist form. For 1b, both of the two independent cations can be described as a combination of rings in an envelop and a twist conformation. According to the NMR spectra, in solution the cations are highly flexible and pseudosymmetrical (point group D 2d )

The crystal and molecular structures of 2,4-dibromo-1-iodo-benzene (1) and 1,3-dibromo-2-iodobenzene (2) have been determined by single crystal X-ray diffraction. The proximity of two or three large halogen substituents (Br/I) induces only minor distortions of the C-C-Br/I angles (ca. 2°) and the halogen atoms remain in the plane of the molecules. These undistorted structures lead to short intramolecular, sub-van-der-Waals Br-I contacts [in the range 3.465(4) to 3.530(4) Å ]. The results suggest that the peripheral Br-I interactions have an attractive component which alleviates the repulsion out of steric crowding. The influence is associated with an absorption in the visible region and is possibly responsible for the enhanced reactivity of the 1,2-dihalobenzene molecules

The reaction of bis(lithiomethyl-methylamino)methane with ditbutylaluminium chloride leads to the formation of 3,3,6,6-tetra- t butyl-1,4-dimethyl-3,6-dialumina-1,4-diaza-norbornane by simultaneous formation of two metal-carbon and two metal nitrogen bonds accompanied by two ring closure reactions. The compound was identified by an NMR analysis ( 1 H, 13 C, 27 Al) and by determination of its crystal structure. Despite the high steric demand of the tbutyl groups, the norbornane-basket structure is favoured over potential isomers containing three-membered rings and over polymeric aggregation. The crystal structure of tri( t butyl)aluminium has been determined. t Bu 3 Al crystallizes as a monomer, with the molecules interconnected by weak secondary Al···C contacts (2.95 Å) leading to a slight deviation of the AlC 3 units from a planar coordination geometry at the Al atoms

The new oxynitride of molybdenum, Na 5 MoO 4 N was prepared from stoichiometric mixtures of the starting materials MoO 2 , Na 2 O 2 and NaN 3 which were heated in a special regime up to 500°C, and cooled down slowly. Its crystal structure was solved and refined from single crystal data (orthorhombic, Cmcm, a = 991.1(2), b = 574.3(1), c = 1067.7(2) pm, R 1 = 0.0153, wR 2 = 0.0427). The structure consists of isolated [MoO4N] 5− rectangular pyramids which are separated by Na + cations. This compound is structurally related to Na 5 WO 4 N which crystallizes in space group Cmc2 1

In contrast to the tetrachlorodigermane (tBu 3 Si)Cl 2 Ge-GeCl 2 (SitBu 3 ), the cis,transcyclotrigermane (tBu 3 SiGeCl) 3 is sensitive to oxygen. Its treatment with O 2 at ambient temperature leads to the trigermoxetane (tBu 3 Si) 3 Ge 3 Cl 3 O. According to an X-ray structure analysis of single crystals consisting of cocrystallized (tBu 3 Si) 3 Ge 3 Cl 3 O and (tBu 3 Si)Cl 2 Ge-GeCl 2 (SitBu 3 ) the trigermaoxetane contains an almost planar Ge 3 O-ring while the tetrachlorodigermane (tBu 3 Si)Cl 2 Ge- GeCl 2 (SitBu 3 ) possesses a Si-Ge-Ge-Si chain which is exactly all trans

Colourless single crystals of the compounds CdXO 4 · 2 HgO (X = S, Se) were obtained under hydrothermal conditions (250 °C, 5 d), starting from stoichiometric amounts of HgO, CdSO 4 ·7H 2 O and CdSeO 4 ·2H 2 O, respectively. The crystal structures were determined from X-ray diffraction data sets. The CdXO 4 · 2HgO compounds crystallise isotypically with two formula units in space group P1̅ (# 2) [CdSO 4 · 2HgO (CdSeO 4 · 2HgO): a = 6.793(2) (6.9097(5)) Å , b = 7.205(2) (7.1786(6)) Å , c=7.359(2) (7.4556(6)) Å ,α =73.224(6) (74.586(2))°, β =66.505(6) (68.229(1))°, γ =63.054(5) (63.886(1))°, 1670 (1786) structure factors, 92 parameters, R[F 2 > 2σ(F 2 )] = 0.0379 (0.0244)] and are made up from zig-zag [O-Hg-O]∞ chains with very short bonds of d̅(Hg-O) 2.025 Å , distorted [CdO 6 ] octahedra (d̅(Cd-O)= 2.297 Å ), and XO 4 tetrahedra (d̅(S-O)= 1.458 Å , d̅(Se-O)= 1.633 Å ) as the main building blocks. The CdXO 4 ·2HgO compounds reveal no structural relationship with the corresponding HgXO 4 ·2HgO phases

Calculations of spin-spin coupling constants 1 J( 17 O, 13 C) in carbon dioxide (1) carbon monoxide (2) and several derivatives using density functional theory (DFT) have been carried out. This coupling constant possesses a positive sign [reduced coupling constant 1 K( 17 O, 13 C)<0] except for the parent acylium cation [H-CO] + (4a). It is shown that the Fermi contact term (FC) is positive [< 0 for 1 K( 17 O, 13 C)] and that there are significant contributions from spin-dipole (SD) and paramagnetic spin-orbital (PSO) interactions

The reaction of Ga 2 (SO 4 ) 3 ·18H 2 O and excess 2,2′:6′,2″-terpyridine (terpy) in MeOH / H 2 O leads to [Ga(OH)(SO 4 )(terpy)(H 2 O)]·H 2 O (1·H 2 O] in good yield. The structure of the complex has been determined by single-crystal X-ray crystallography. The GaIII atom in 1·H 2 O is 6-coordinate and ligation is provided by one terdentate terpy molecule, one monodentate sulfate, one terminal hydroxide and one terminal H 2 O molecule; the coodination polyhedron about the metal is described as a distorted octahedron. There is an extensive hydrogen-bonding network in the crystal structure which generates corrugated layers parallel to bc. The new complex was characterized by IR and 1 H NMR spectroscopy. The spectroscopic data are discussed in terms of the nature of bonding

The reaction of antimony(III) oxide with ethylamine, in molar ratios from 1:1 to 1:10, in concentrated hydrobromic acid leads to the formation of one product - bis(ethylammonium) pentabromoantimonate( III). The structure of (C 2 H 5 NH 3 ) 2 [SbBr 5 ] was determined at 298 and 90 K, below and above the phase transition that occurs at about 158.5 K. The orthorhombic system was found in both phases, space groups Cmca and Pbca at 298 and 90 K, respectively. At both temperatures the structure consists of [SbBr 6 ] 3− octahedra connected via cis bromine atoms forming one-dimensional zig-zag [{SbBr 5 } 2− ]n chains. The ethylammonium cations fill the space between polyanionic chains. The organic and inorganic substructures are held together by a system of N(-H)···Br interactions. Their influence on the deformation of [SbBr 6 ] 3− octahedra is well reflected in differences in the corresponding Sb-Br bond lengths and Br-Sb-Br angles in both phases. The phase transition is of the first order and the order-disorder type. It is related to changes in the molecular dynamics of the ethylammonium cations. In the low-temperature phase the organic cations are ordered, while at 298 K both crystallographically independent cations are disordered. The type of disorder is realized by the presence of two positions of the methyl carbon atoms

Two unnatural α-amino acid esters were prepared in good yields via phase transfer catalyzed Michael addition of ethyl N-acetylaminocyanoacetate to chalcone and benzalketone. For both α- enones, a progressive increase in product diastereomeric excess (d.e.) was observed during the course of reaction, even in the absence of quaternary ammonium salt. However, for a fixed reaction time, higher d.e. values were obtained under phase transfer catalytic condition. Analogous reactions were performed using S-aryl thiocinnamates as Michael acceptors, affording a 2-pyrrolidinone in good yield but low d.e. These results were interpreted on the basis of the reversibility of the Michael reaction

An iron(II) mixed-ligand complex with 1,10-phenanthroline (phen) and dipyrido[3,2-a:2’,3’- c]phenazine (dppz), [Fe(phen) 2 (dppz)] 2+ , has been synthesized. The DNA-binding properties of the mixed-ligand complex have been studied in terms of equilibrium binding constant, thermodynamic parameter, thermal denaturation as well as Pfeiffer effect upon binding to DNA. The spectrophotometric titration of [Fe(phen) 2 (dppz)] 2+ with calf thymus DNA (ct-DNA) has shown that the iron(II) mixed-ligand complex binds effectively to ct-DNA in an intercalation mode as indicated by remarkable hypochromicity (ca. 36%) and moderate bathochromic shift (8 nm) of the absorption spectra. This intercalative mode is supported by a significant increase (Δ Tm = 21 °C) in the melting temperature (Tm) of ct-DNA at R([complex]/[ct-DNA]) = 1.5. The binding of [Fe(phen) 2 (dppz)] 2+ to ct-DNA is entropically driven as characterized by a positive enthalpy change and a large negative TΔ S term. An intense CD signal in the UV and visible region develops upon addition of ct-DNA to the racemate solution of [Fe(phen) 2 (dppz)] 2+ . This has revealed that a shift in diastereomeric inversion equilibrium takes place in the solution to yield an excess of one enantiomer of the DNA-iron(II) complex (Pfeiffer effect). The striking resemblance of the CD spectral profiles to those of the corresponding Δ -enantiomer indicates that Δ -[Fe(phen) 2 (dppz)] 2+ is preferentially bound to ct-DNA

The microbial transformation of oral contraceptive norethisterone (1) by Cephalosporium aphidicola afforded an oxidized metabolite, 17α-ethynylestradiol (2), while the microbial transformation of 2 by Cunninghamella elegans yielded several metabolites, 19-nor-17α-pregna-1,3,5 (10)- trien-20-yne-3,4,17β -triol (3), 19-nor-17α-pregna-1,3,5 (10)-trien-20-yne-3,7α,17β -triol (4), 19- nor-17α-pregna-1,3,5 (10)-trien-20-yne-3,11α,17β -triol (5), 19-nor-17α-pregna-1,3,5 (10)-trien-20- yne-3,6β ,17β -triol (6) and 19-nor-17α-pregna-1,3,5 (10)-trien-20-yne-3,17β -diol-6β -methoxy (7). Metabolite 7 was found to be a new compound. These metabolites were structurally characterized on the basis of spectroscopic techniques

A new metabolite, 6-(4’-hydroxy-2’-methyl phenoxy)-(-)-(3R)-mellein (1) was isolated from the ethyl acetate extract of Aspergillus terreus culture medium along with three known isocoumarin derivatives, (-)-(3R)-6-methoxymellein (2), (-)-(3R)-6,7-dimethoxymellein (Kigelin) (3) and (3R, 4R)-6,7-dimethoxy-4-hydroxymellein (4). Metabolites 1 and 4 showed significant activity against human pathogenic dermatophytes, Microsporum canis and Trichophyton longifusus. Metabolite 1 also exhibited potent antioxidant activity. The structures of metabolites were characterized on the basis of spectroscopic techniques. 13C NMR data of metabolites 2 - 4 are also being reported for the first time

Two new ceramides have been isolated from Tanacetum artemisioides, besides the known constituents β -sitosterol and β -sitosterol glycoside. The structure elucidation of the isolated new compounds was based primarily on 1D and 2D NMR analysis, including COSY, HMQC, HMBC correlations. The compound 1 and 2 showed inhibitory activity against acetylcholinesterase

Bioactivity-directed fractionation led to the isolation of a new N-(methoxycarbonyl) phenanthrene alkaloid, romucosine I (1), along with three known N-(methoxycarbonyl) alkaloids, romucosine C (2), tuduranine (3), and promucosine (4). The structures of these compounds were identified on the basis of spectral data and chemical evidence. A proposed biogenesis about these isolates is also reported in this paper

A rapid, easy, regio- and stereoselective synthesis of 3-halo-3-deoxy sugars using titanium tetrahalides is described. To fully confirm the stereochemistry of the synthetic products, the X-ray structure of benzyl 3-chloro-3-deoxy-β -L-xylopyranoside was determined

Two new cyclolignan glycosides, (+)-lyoniresinol 3a-O-α-D-galactopyranosyl-(1 → 6)-β -D-glucopyranoside (1) and (+)-lyoniresinol 2a-O-α-D-galactopyranosyl-3a-O-β -D-glucopyranoside (2) were isolated from the aerial parts of Acanthus ilicifolius. Their structure elucidation is based on the analyses of spectroscopic data

The title compound, As[C 6 H 3 (CF 3 ) 2 ] 3 , has been synthesised by Grignard reaction from arsenic trichloride and 3,5-bis(trifluoromethyl)phenylmagnesium bromide. It crystallises in the triclinic space group P1̅ with two formula units in the asymmetric unit. The most prominent feature of the crystal structure is the protrusion of a phenyl group of one molecule into the cavity at the base of the pyramid of a second molecule. The crystal structure is then built up by densely packing these units of interlocked molecules to form columns, which are arranged in parallel in a distorted hexagonal pattern

The yellow titanium(IV) carbene complex [TiCl 4 (1)], 2 (1 = N,N’-bis(2,2-dimethylpropyl)benzimidazol-2-ylidene) was synthesized by reaction of TiCl 4 and the benzannulated carbene 1 in toluene. The X-ray structure analysis revealed a mononuclear complex with a titanium(IV) center coordinated in a distorted trigonal-bipyramidal fashion by the carbene ligand in an equatorial position and four chloro ligands

The reaction of phenylpentazole, C 6 H 5 -cyclo-N 5 , with n-butyl lithium in tetrahydrofuran or in diethylether does not yield a lithium pentazolide such as Li(THF) 4 + N 5 −. Instead, a mixture of several primary products is obtained, which probably include lithium 1-n-butyl-5-phenyl-pentaazadienide, Li + [n-C 4 H 9 − N=N−N−N=N−C 6 H 5 ]− and di-n-butyl-phenylhydrazide, Li + [(n-C 4 H 9 ) 2 N−N−C 6 H 5 ]−. After hydrolysis 1,1-di-n- butyl-2-phenylhydrazine, (n- C 4 H 9 ) 2 N−NH−C 6 H 5 , is ob- tained with good yield. This compound is an oil that was characterized by NMR, mass and IR spectroscopy