Volume 60, Issue 3

Selective formation of 3,3,6,6-tetra- t butyl-1,4-dimethyl-3,6-digallium-1,4-diaza-norborane is achieved by the reaction of bis(lithiomethyl-methylamino)methane with di t butylgallium chloride by simultaneous formation of two dative metal-carbon and two metal-nitrogen bonds accompanied by two ring closures. Despite the high steric demand of the tbutyl groups, the norbornane-like structure is favoured over potential isomers containing three-membered rings and over polymeric aggregation. The compound was identified by elemental analysis, NMR spectroscopy ( 1 H, 13 C) and by determination of its crystal structure in which it is present as a monomer

The syntheses of di t butylaluminium and -gallium iodide via metathesis reactions of the respective chlorides with lithium iodide are reported. The compounds were identified by elemental analyses, multinuclear NMR spectroscopy ( 1 H, 13 C, 27 Al) and mass spectra (EI). The structures obtained by single crystal X-ray diffraction reveal that the new compound t Bu 2 AlI crystallizes in the monoclinic crystal system, space group P2 1 /n, as a dimer with a planar Al 2 I 2 four-membered ring. The crystal structure of the monoclinic structure of t Bu 2 GaI was redetermined. Its mass spectra reveal the existence of trimers and dimers in addition to the predominant monomeric species in gas phase

The reaction of the di(alkyn-1-yl)silanes Me 2 Si(C≡CSiMe 2 H) 2 1a and Me(H)Si(C≡CSiMe 2 H) 2 1b with triethylborane was studied. In the case of 1a, the 4-ethyl-3-diethylboryl-1,1-dimethyl-2,5- bis(dimethylsilyl)-1-sila-2,4-cyclop entadiene 2a was the sole product. In the case of 1b, the analogous silole 2b was formed along with two other products which were identified as di(alkenyl)silanes 3b and 4b, in which different types of electron-deficient Si-H-B bridges could be detected. All products were characterised by consistent sets of solution NMR data ( 1 H, 11 B, 13 C and 29 Si NMR). The coupling constants 1 J( 13 C, 13 C) were measured for 2a and calculated by using DFT methods (B3LYP/6-311+G(d,p) level of theory)

Trimethylborane (1), triethylborane (2), 1,3-dimethyl-1-boracyclopentane (3), 1-methyl-1- boracyclohexane (4), 9-methyl- and 9-ethyl-9-borabicyclo[3.1.1]nonane [5(Me) and 5(Et)], and 1- boraadamantane (6) were studied by 11 B and 13 C NMR spectroscopy with respect to coupling constants 1 J( 13 C, 11 B) and 1 J( 13 C, 13 C). Results of DFT calculations at the B3LYP/6-311+g(d,p) level of theory show satisfactory agreement with the experimental data. Hyperconjugation arising from C-C σ bonds adjacent to the tricoordinate boron atom is indicated, in particular for 1-boraadamantane (6), by the optimised calculated structures, and by the experimental and calculated data 1 J( 13 C, 13 C). The calculated magnitude of 1 J( 13 C, 1 H) for carbon atoms adjacent to boron becomes significantly smaller if the optimised structures suggest hyperconjugative effects arising from these C-H bonds

The rare earth metal (RE)-magnesium-thallides REMgTl (RE = Y, La-Nd, Sm, Gd-Tm, Lu) were prepared from the elements in sealed tantalum tubes in a water-cooled sample chamber of a high-frequency furnace. The thallides were characterized through their X-ray powder patterns. They crystallize with the hexagonal ZrNiAl type structure, space group P62m, with three formula units per cell. Four structures were refined from X-ray single crystal diffractometer data: α = 750.5(1), c = 459.85(8) pm, wR2 = 0.0491, 364 F 2 values, 14 variables for YMgTl; α = 781.3(1), c = 477.84(8) pm, wR2 = 0.0640, BASF = 0.09(2), 425 F 2 values, 15 variables for LaMgTl; α = 774.1(1), c = 473.75(7) pm, wR2 = 0.0405, 295 F 2 values, 14 variables for CeMgTl; a = 760.3(1), c = 465.93(8) pm, wR2 = 0.0262, 287 F2 values, 14 variables for SmMgTl. The PrMgTl, NdMgTl, GdMgTl, TbMgTl, and DyMgTl structures have been analyzed using the Rietveld technique. The REMgTl structures contain two cystallographically independent thallium sites, both with tri-capped trigonal prismatic coordination: Tl1Mg 3 RE 6 and Tl2Mg 6 RE 3 . Together the magnesium and thallium atoms form three-dimensional [MgTl] networks with Mg-Mg distances of 327 and Mg-Tl distances in the range 299 - 303 pm (data for CeMgTl)

The rare earth metal (RE)-nickel-cadmium intermetallics RE 2 Ni 2 Cd (RE = La, Pr, Nd, Sm, Tb, Dy) were prepared from the elements in sealed niobium or tantalum tubes in a water-cooled sample chamber of a high-frequency furnace. They crystallize with a tetragonal Mo 2 FeB 2 type low-temperature modification, space group P4/mbm, and an orthorhombic Mn 2 AlB 2 type hightemperature modification, space group Cmmm. The cadmium compounds were characterized through their X-ray powder patterns. Five structures of the low-temperature modifications were refined from X-ray single crystal diffractometer data: α = 763.76(9), c = 387.26(8) pm, wR2 = 0.046, 205 F 2 for La 2 Ni 1.67 (1)Cd; α = 752.93(7), c = 380.95(6) pm, wR2 = 0.061, 260 F 2 for Pr 2 Ni 2 Cd; α = 750.88(9), c = 378.33(7) pm, wR2 = 0.051, 195 F 2 for Nd 2 Ni 2 Cd; α = 743.6(1), c = 374.0(1) pm, wR2 = 0.036, 386 F 2 for Sm 2 Ni 1.93 (1)Cd; α = 734.9(1), c = 366.1(2) pm, wR2 = 0.030, 252 F 2 for Dy 2 Ni 1.94 (1)Cd, with 13(12) variables per refinement. The 4g nickel site is only fully occupied in the neodymium and the praseodymium compound. Both modifications can be considered as intergrowths of distorted AlB 2 and CsCl related slabs. In both modification the nickel and cadmium atoms build up two-dimensional [Ni 2 Cd] networks. In the low-temperature modifications the nickel atoms form pairs, while nickel zig-zag chains occur in the high-temperature modifications. These nickel fragments are condensed via the cadmium atoms. The crystal chemistry and the chemical bonding in these intermetallics is discussed

The new compounds K 4 Ge 9 ·9 NH 3 and Rb 4 Ge 9 ·5 NH 3 were prepared by the extraction of K 4 Ge 9 and Rb 4 Ge 9 with liquid ammonia and characterized by low temperature X-ray structure analysis. They both contain monocapped square antiprismatic Ge 9 4− anions. Cs 6 Ge 18 ·4 NH 3 was prepared by the extraction of K 2 Cs 2 Ge 9 with liquid ammonia in the presence of [(Bu) 3 MeN](Br 2 I) as an oxidizing agent, and contains a [Ge 9 -Ge 9 ] 6− dimer in which two Ge 9 4− anions are linked by a single Ge-Ge bond

A new Ti 5 Te 4 -type compound, Zr stabilized hafnium telluride was discovered and characterized with electron crystallography. Microanalyses and preparative work show that Zr stabilizes Ti 5 Te 4 - type hafnium telluride and destabilizes the competing phase, Hf 3 Te 2

The mercury(II) complexes of 2,2′-bipyridine (bpy), [Hg(bpy)(NO 2 ) 2 ], [Hg(bpy)(NO 2 ) (CH 3 COO)], and [Hg(bpy)(NO 2 )(NCS)] have been synthesized and characterized by elemental analysis, IR, 1 H NMR and 13 C NMR spectroscopy. The structure of [Hg(bpy)(NO 2 ) 2 ] has been confirmed by X-ray crystallography. The complex is a monomer and the Hg atom has an unsymmetrical six-coordinate geometry, formed by two nitrogen atoms of the bpy ligand and four oxygen atoms of the two nitrite anions. There is a short intermolecular π-π stacking interaction between parallel aromatic rings

The 2-methylenimidazolines ImC(CN) 2 (6a - c, Im = 1,3-dialkyl-4,5-dimethylimidazol-2-ylidene) are prepared by the reaction of the imidazolium salts [ImBr]Br (5) and malodinitrile while ImC{C(O)Ph} 2 (7) is obtained from ImCH 2 (2) and benzoic fluoride. Both the structural data of 6b, 6c, and 7 and the 13 C NMR data demonstrate the influence of steric and electronic effects on the charge separation and the nonplanar arrangement of the substituents attached at the carbon atoms of the central olefinic bond

Lead(II) complexes with 2,2′-bipyridine (bpy) containing two different anions, [Pb(bpy)(CH 3 - COO)X] (X = I - , NO 3 - , and ClO 4 - ), have been synthesized and characterized by CHN elemental analysis, IR-, 1 H NMR- and 13 C NMR spectroscopy. The structure of [Pb(bpy)(ClO 4 )(CH 3 COO)]n was confirmed by X-ray crystallography. The complex is a one-dimensional polymer as a result of perchlorate ligand bridging. The Pb atom has an unsymmetrical eight-coordinate geometry. The arrangement of the bpy, acetate and nitrate ligands leaves a coordination gap at the Pb(II) ion, occupied probably by a stereo-active lone pair of electrons. There is a π- π stacking interaction between the parallel aromatic rings that may be formed by influence lone pair activity

Two new vanadyl(IV) carboxylate complexes have been obtained: Na 2 [VO(Fer) 2 (CH 3 OH) 2 ] and Na 2 [VO(Cin) 2 (CH 3 O) 2 ] and characterized by elemental analysis and UV-vis, diffuse reflectance and IR and Raman spectroscopies (FerH 2 = ferulic acid, CinH= cinnamic acid). The thermal behavior was also investigated. The inhibitory effect on alkaline phosphatase activity was tested for the compounds and ferulic and cinnamic acids as well as for the vanadyl(IV) complex of quinic acid for comparison. The ferulic complex together with the free ligands exhibited the lowest inhibitory effect, while the VO/quinic and VO/cinnamic complexes showed an intermediate inhibition potential

The commercial zeolite sodic mordenite was chemically and thermally treated in order to obtain materials with different physico-chemical properties to be employed as support for the metallocene bis(cyclopentadienyl)zirconium dichloride used for ethylene polymerization. The supports obtained were characterized regarding their chemical composition, textural properties as well as Lewis and Brφnsted sites concentrations. It was verified that the original zeolite without dealumination treatment was the most active catalyst followed by the material dealuminated with steam. All the supported catalysts produced polyethylene with higher molecular weight in relation to that obtained with the homogeneous counterpart

Sulphadiazine, [4-amino-N-(2-pyrimidinyl)-benzenesulfonamide], reacts with (dppe)Au 2 Cl 2 and triethylamine in methanol to produce [(SDAZ) 2 Au 2 (dppe)]. The structure of this novel complex was analyzed by single crystal X-ray diffraction. In [(SDAZ) 2 Au 2 (dppe)] the ligands SDAZ− and dppe have approximately the same bond distances and angles as found for the protonated and free ligand, respectively. The compound is assembled essentially of two gold atoms bonded to the phosphorus centers of one 1,2-bis(diphenylphosphanyl)ethane molecule (in an anti conformation). The coordination sphere is completed with a trans sulphadiazine ligand on each gold atom. Because of their fairly high reactivity, the two aromatic amine groups in the SDAZ ligands represent important sites for the chemical modification of the complex with biological purposes

Bi 2 O 2 (OH)(NO 3 ) is the first bismuth oxynitrate containing [Bi 2 O 2 ] 2+ layers for which the crystal structure has been determined. The current study presents its synthesis, formula determination using powder XRD, thermogravimetric analysis and nitrate assay, and finally, crystal structure refinement from twinned crystals. Bi 2 O 2 (OH)(NO 3 ) crystallizes in the orthorhombic system, a = 5.3878(11), b = 5.3984(10) and c = 17.136(2) Å , with the space group Cmc2 1 . The structure refinement based on 1257 independent reflections converged to R I (obs) = 0.0321 and R Iw (obs) = 0.0765. The Bi 2 O 2 (OH)(NO 3 ) structure is based on [Bi 2 O 2 ] 2+ sheets in the (ab) plane. The interlayer space is composed of two slices containing OH − and (NO 3 ) − groups, respectively. Within the nitrate layers, the disorder over two possible NO 3- orientations (related by a four fold axis) involves half occupied positions for two of the oxygen atoms. An attempt to lower the symmetry and/or enlarge the unit cell, looking for an (NO 3 ) − ordering, failed

From the aerial parts of Marrubium velutinum, two new phenylethanoid glycosides, velutinosides III-IV have been isolated together with four known phenylethanoid glycosides, as well as one new acylated flavone and five known flavonoids. The structures of the isolated compounds were established by means of NMR, MS, and UV spectral analyses

A new pigment, phlegmacin A 8,8’-di-O-methyl ether (1), was isolated from fruiting bodies of Xylaria euglossa (Ascomycota) along with the known fungal pigments (S)-torosachrysone-8-O-methyl ether (2) and emodin-6,8-di-O-methyl ether (3). The structure of compound 1 was established on the basis of its spectroscopic data and the absolute configuration determined as P and 3’S by comparing the CD and 1 H NMR spectra of 1 with those of the phlegmacins 4 and 5. Compound 1 represents the first phlegmacin type pigment isolated from the ascomycete

O-Alkyl (N-phenylanthranilo)hydroxamic acids 2, easily available by condensation of Nphenylanthranilic acid 1 with 1,1’-carbonyldiimidazole and the appropriate hydroxylamine in tetrahydrofuran, are cyclized by oxalyl chloride in the presence of imidazole to give 4-alkoxy-2,3,4,5- tetrahydro-1H-1,4-benzodiazepine-2,3,5-triones (3) in fair to good yields

Steroidal galactoside 1 and aryl esters 2 and 3 have been isolated from Buddleja crispa, along with ginipin 4, gardiol 5, 1-heptacosanol 6, and methyl benzoate 7, isolated for the first time from this species. The structures of all of the compounds were determined by spectroscopic techniques and chemical studies. The steroidal galactoside 1 is an inhibitor of lipoxygenase. Compounds 1- 3 displayed inhibitory activity against butyrylcholinesterse, while compounds 2 and 3 further showed inhibition against acetylcholinesterase

A new triterpenoid, glaucinoic acid (2α, 3β, 19α, 24-tetrahydroxyolean-12-en-30-oic acid) (1) along with several known compounds, arjunic acid (2), arjungenin (3), sericoside (4), and friedelin (5) were isolated from the stem barks of Terminalia glaucescens. These compounds showed β - glucuronidase inhibitory activity. The structures were identified on the basis of spectroscopic techniques

The fruits of Cipadessa fruticosa Bl. afforded two new limonoids: methyl 8α,30α-epoxide-3β - (2’-methylbutyryloxy)-1-oxomeliacate (cipadesin A) and methyl 21,23-dihydro-23-hydroxy-21-oxo- 3β -tigloyloxy-1-oxomeliac-8(30)-enate (febrifugin A), along with the known limonoids cipadesin, khayasin T, febrifugin, ruageanin A and mexicanolide. Their structures were elucidated on the basis of spectroscopic methods

Two new prenylated flavonoids (1, 2), together with five known compounds, were isolated from the stem bark of Pongamia pinnata. Their structures were characterized on the basis of spectral data

Complexes of the general composition Rh III (phpy) 2 (S∪E) with phpy − = 2-(2-pyridyl)phenyl and S∪E− = diethyldithiocarbamate, 2-pyridinethiolate and 2-quinolinethiolate were prepared and characterized. The complexes with S∪E − = diethyldithiocarbamate and 2-pyridinethiolate show a low-temperature luminescence which originates from a phpy ππ ∗ intraligand triplet. For the complex with S∪E − = 2-quinolinethiolate (or thiooxinate) the lowest-energy excited state is of the quinolinethiolate intraligand type. This complex displays a fluorescence as well as a phosphorescence under ambient conditions