Volume 56, Issue 6

The reaction of Te, TeCl 4 and BiCl 3 in a sealed evacuated glass ampoule in a temperature gradient 160 to 90 °C yields Te 8 [Bi 4 Cl 14 ] as black platelike crystals with a golden lustre which are deposited in the temperature zone 150 to 130 °C. The best yield is obtained with a Te/TeCl 4 /BiCl 3 molar ratio of 15/3/4. The crystal structure determination (orthorhombic, P2 1 2 1 2 1 , a = 879.9(3), b = 1642.3(4), c = 2267.3(8) pm, Z = 4) shows that Te 8 [Bi 4 Cl 14 ] consists of a novel one-dimensional (Te 8 2+ )„ polycation and a two-dimensional chlorobismutate anion Bi4Cl 14 2- . The structure of the cation consists of boat shaped Te 6 rings which are connected in the 1,4-positions by Te 2 groups to a one-dimensional polymeric strand. The structure is substantially different from the previously reported Te 8 2+ polycations in Te8[WCl 6 ] 2 and Te 8 [MCl 6 ] (M = Zr, Hf, Re) where discrete bicyclic clusters with only weak interionic interactions are present. The Bi 4 Cl 14 2- ion can be described as built up of BiCl 3 molecules which are connected by Cl - ions to a two-dimensional network [(BiCl 3 ) 4 (Cl - ) 2 ] n .

The reaction of N,N′-di( t butyl)-ethane- 1,2-diamine with NaH followed by anhydrous GaCl 3 (molar ratios 1:2 :1) gives mainly an insoluble bis(diamido)gallium chloride together with a low yield (28%) of a soluble monocyclic dichlorogallium-[2-( t butylamino)-ethyl-( t butyl)amide], Cl 2 Ga( t BuNH-CH 2 CH 2 -N t Bu) 1, the structure of which has been determined. Metallation of the same diamine with t butyl-lithium and GaCl 3 (1:2:1) gave small quantities of the corresponding dinuclear, bicyclic gallium(II) compound 2, [( t BuNH-CH 2 CH 2 -N t Bu)GaCl] 2 with a Ga-Ga single bond connecting the two units, as again shown by a single crystal X-ray diffraction analysis.

The metal-rich intermetallic compounds NblrSi, NblrGe, and TalrSi were synthesized by arc-melting of the elements and subsequent annealing in glassy carbon crucibles in a high-frequency furnace. The three compounds were investigated by X-ray diffraction on powders and single crystals: TiNiSi type, Pnma, a = 641.27(3), b = 379.48(2), c = 727.70(3) pm, wR2 = 0.0773, 430 F 2 values for NblrSi, a = 645.48(3), b = 389.21(2), c = 741.11(4) pm, wR2 = 0.0981, 297 F 2 values for NblrGe, and a = 638.11(3), b = 378.69(2), c = 726.78(3) pm, wR2 = 0.0887, 290 F 2 values for TalrSi with 20 variables for each refinement. The iridium and silicon (germanium) atoms form a three-dimensional network of puckered Ir 3 Si 3 and Ir 3 Ge 3 hexagons in which the niobium (tantalum) atoms fill larger cages. Magnetic susceptibility measurements on NblrSi and TalrSi indicate Pauli paramagnetism with room temperature susceptibilities of 0.30(5)·10 -9 and 0.97(5)·10 -9 m 3 /mol, respectively.

Four differently methyl-substituted tetraphenyl imidodiphosphates [(H 3 C)nC 6 H 5-n ] 2 PO-NH-PO[C 6 H 5-n (C 3 ) n ] (n = 1, 2), i. e. the 4-, 3,4-, 3,5-and 2,3-derivatives, have been crystallized and their structures determined to gain information on the spatial requirements as ligands in the corresponding cesium salts. According to the packing coefficients calculated from the structural data, they increase in the sequence 4<3,5<3,4<2,3. The most perturbed structural motif is the hydrogen bonded, eight-membered of each the dimer subunits.

In alkali-tetraphenylimidodiphosphate ion aggregates, the size of the cation determines the curvature of the ligand and, therefore, whether hexameric ellipsoidal clusters or polymeric chains are formed. To further characterize the ligand spatial requirements, the phenyl rings have been methylsubstituted in 4-, 3/5-, 3/4- or 2,3-positions, their conformations structurally analyzed and correlated with the van der Waals substituent profiles. In addition, relativistic density functional theory potential curves have been calculated for the Cs⊕ ··· Cs⊕ interactions in simplified model systems.

Consolidated stoichiometric mixtures of graphite fluoride (1) and magnesium (2) upon igni­ tion under argon atmosphere (0,1 MPa) yield very high flame temperature of ~ 5600 K as determined by infrared emission spectroscopy. The combustion product was analysed by X-ray powder diffraction and revealed the presence of magnesium fluoride and graphite as well as structurally low ordered carbon. A possible reaction mechanism is discussed.

A novel heptacoordinated thiosemicarbazonato lead(II) complex [Pb(4ML)(SCN)] (4ML = 2-Acetylpyridine- 4 N-methylthiosemicarbazonato) was synthesized and characterized by conventional methods (IR and elemental analysis) and single-crystal X-ray diffraction. [Pb(4ML)(SCN)] shows an unusual polymeric structure in which the lead atom is hexa-coordinate, the deprotonated thiosemicarbazone both chelates and bridges, and the thiocyanate group acts as bridge between lead(II)-thiosemicarbazonate fragments. There is hydrogen-bonding between the polymeric chains. The complex crystallizes in the triclinic space group P 1̅̅ with a = 7.461(2), b = 9.572(2), c = 11.235(2) Å, α = 66.51(3), β = 84.01(3), γ = 68.75(3)°, V = 685.1(2) Å 3 , Z = 2.

N ,N-Dimethylethylenediammonium pentachloroantimonate(III) crystallizes in the monoclinic system, in space group P2 1 /c (a = 12.460(2), b = 10.252(2), c = 10.330(2) Å, β = 97.75(3)°, V = 1307.5(4) Å 3 , Z = 4, d c = 1.997, d m = 1.99(2) g/cm 3 ). The crystal structure of [(CH 3 ) 2 NH(CH 2 ) 2 NH 3 ][SbCl 5 ] consists of isolated [SbCl 5 ] 2- anions and [(CH 3 ) 2 NH(CH 2 ) 2 NH 3 ] 2+ cations. The [SbCl 5 ] 2- anion has a distorted square pyramidal geometry, presenting one short axial and four long equatorial Sb-Cl bonds. The square pyramids are characteristically stacked one close to the other, parallel to the c axis. The voids between the anionic sublattice are filled by [(CH 3 ) 2 NH(CH 2 ) 2 NH 3 ]2+ cations. The five non-equivalent Sb-Cl bond distances within the [SbCl 5 ] 2- square pyramid are significantly different. The equatorial Sb-Cl bonds are in the range 2.427(2)-2.968(2) Å, whereas the axial one is 2.384(1) Å long. The study reveals that N-H...C1 hydrogen bonds are responsible for the deformation of equatorial Sb-Cl bonds from the mean value of 2.654(7) Å. Analysis of intermolecular interactions between the [SbCl 5 ] 2- pyramids in the structure, reflected in changes of Sb-Cl bond lengths from the values characteristic of non-interacting pyramids, leads to the conclusion that the van der Waals radius of Sb is significantly smaller than that estimated by Pauling.

The acid-labile 5-[(9-aminoxanthen-2-yl)oxy]valeric acid was prepared in a six-step route. The usefulness of the resulting handle was investigated with solid-phase peptide synthesis of cholecystokinin-8 sulfate and the phosphorylated fragment of the ζ-subunit of the T-cell receptor complex 138-144.

The α-dicarbonylmonophenylhydrazones 1 and 8 do not react as simple ,,CH-acidic compounds“ in the Mannich condensation reaction. In a concerted reaction with aminals in absolute dioxane they give rise to the products 5a-e and 10a-e with better practicability and much higher yields compared with the conventional method. The formal Mannich bases 5a/5b/5d and 10a/10b/10d with a cyclic amine part show in the dehydrogenation, using mercury- EDTA , a neighbouring group participation of the phenylhydrazono moiety yielding the corresponding lactams. With 5c only cyclization occurs leading to 1,2,4-triazine 19 in low yield, while 10c shows no dehydrogenation but an amine elimination to the vinyl-azo com pound 21 with consecutive cycloaddition leading to the 1,2-diazine 23.

Cbz protected α-aminonitriles 1 or α-aminocarboxamides 2 were converted to imidates 3 either by Pinner reaction or by Meerwein’s reagent. Sulfhydrolysis of 3 produced α-aminothiocarboxylic O-esters 4 which in turn were reacted with hydroxylamine to give Cbz protected (E)-α-aminocarbohydroximic esters 5. Hydrogenolysis of 5 furnished the target compounds 6 .

A new synthesis of the racemates of two naturally occurring neolignans 1 and 2 was achieved via the 2,3-dihydrobenzo[b]furan derivative 3, starting from the commercially available materials o-vanillin (6) and acetovanillone (9).