Volume 52, Issue 12

KAl 2 (PO 4 ) 2 (OH)·4H 2 O could be obtained by the reaction of gibbsite with a potassium-phosphate solution of pH = 5.5 at 333 K. A single crystal X-ray structure analysis showed that KAl 2 (PO 4 ) 2 (OH)·4H 2 O is isotypic with the mineral minyulite. Crystal data: orthorhombic space group Pba2, a = 934.7(1), b = 982, 1 (1), c = 551,0(1) pm, Z = 2. It possesses dimeric units of Al-octahedra which are bridged by an OH-and two bidentate phosphate groups. The dimers are linked by phosphate to plane polar layers. Cavities in the layers are occupied by K ions. One corner of each phosphate tetrahedron is not connected to Al but accepts four hydrogen bonds from water molecules bound to Al of the adjacent layer. A powder neutron scattering experiment with KAl 2 (PO 4 ) 2 (OD)·4D 2 O showed that four D atoms and P coordinate the hydrogen bond accepting O in KAl 2 (PO 4 ) 2 (OD)·4D 2 O like a square pyramid. Analogous dimeric building units are found in the Al phosphate minerals minyulite and morinite; similar dimers of Fe octahedra occur in the mineral copiapite, a number of Fe containing enzymes and numerous synthetic iron complexes. High-resolution 31 P solid-state NMR spectra show only one isotropic line at δ iso = -9.6 ppm and confirm the presence of one symmetry independent phosphorus site in the unit cell. In the 1 H-MAS-NMR spectra the water molecules and the bridging OH groups show signals at 5.4 and 1.4 ppm, respectively

KAl 2 (PO 4 ) 2 (OH)·2H 2 O was obtained by the reaction of gibbsite with a potassium-phosphate solution of pH = 5.5 at 373 K. A single crystal X-ray structure analysis showed that it is an ordered, F-free K-analog of the microporous compound AIPO 4 -CI 2 . Crystal data: orthorhombic space group P2 1 2 1 2 1 , a = 920.5(1), b = 970.7(2), c = 982.8(2) pm, Z = 4. The structure consists of dimeric units of AIO 6 octahedra and AIO 5 trigonal bipyramids, bridged by an OH and two bidentate phosphate groups. The dimers are linked by phosphate to form corrugated layers which are topologically related to the layers in KAl 2 (PO 4 ) 2 (OH)·4H 2 O and minyulite. The layers are connected by Al-O-P and hydrogen bonds to a three dimensional framework structure with K ions in channel-like cavities. A neutron powder scattering experiment with KAl 2 (PO 4 ) 2 (OD)·2D 2 O showed that the bridging OD group and only one D of each water molecule are involved in hydrogen bonding. 31 P MAS NMR spectra show two isotropic lines at δ iso = -6.9 and -18,7 ppm of the intensity ratio 1:1 and confirm the presence of two crystallographically independent P atoms in the unit cell. In the 1 H MAS NMR spectra the water molecules and the bridging OH group show signals at 5.9 and 1.1 ppm, respectively.

Single crystals of the compounds Cd(pyrazine)Br 2 , Cd(pyrazine)I 2 , Cu(pyrazine)Cl 2 and Cd(pyrimidine)(NO 3 ) 2 ·2H 2 O were obtained by crystallisation from aqueous solutions of the metal salts and solutions of the respective diazine in an organic solvent. The structures of the pyrazine complexes consist of “supramolecular” networks of -M-pyrazine-M-and -M -(μ 2 -Hal) 2 -M-chains. The pyrimidine complex shows a three dimensional network due to -M-pyrimidine-M-chains connected via hydrogen bonds between H(H 2 O) and O(ONO 2 ).

The phase Bi 2 O 2 Te exists in the pseudobinary system Bi 2 O 3 /Bi 2 Te 3 . The thermal behaviour of Bi 2 O 2 Te was determined by DTA and X-ray analysis: The phase exists up to 620 °C and decomposes into the solid phases Bi 12 TeO 20 , Bi 10 Te 2 O 19 [1] and liquid BiTe. The relations of the phase coexistences in the pseudobinary system and in the ternary area Bi 2 O 3 /TeO 2 /Bi 2 Te 3 /Te were investigated by solid state reactions, chemical transport reactions, and by total pressure measurements.

The five compounds LnZnSbO (Ln = La - Nd, Sm) were prepared by annealing cold-pressed pellets of the lanthanoids, zinc oxide, and antimony, or by reacting these components in a NaCl/KCl flux. They crystallize with the tetragonal ZrCuSiAs type structure, which was refined from single-crystal X-ray data of CeZnSbO : P 4/nmm, a = 419.76(4), c = 947.4(1) pm, Z = 2, R = 0.022 for 165 structure factors and 12 variable parameters. Chemical bonding in this and the formally isotypic compound CeZn 1-x Sb 2 is briefly discussed.

Trichloro-[tris(2-(diphenylphosphanyl)ethyl)amine]-trigold(I) (1) has been prepared by treating the tripod ligand tris(2-(diphenylphosphanyl)ethyl)amine with three equivalents of chloro(dimethylsulfide)gold(I) in dichloromethane. Treatment of solutions of 1 in dichloromethane with potassium bromide or potassium iodide resulted in the formation of the tribromo (2) and triiodo (3) derivatives. All compounds were crystallized and X-ray structure analyses have been performed. Complexes 1 and 2 are isomorphous and crystallize in the rhombohedral space group R3̄. An aggregation into layers through Au-X′ contacts of 3.734 (X = Cl) and 3.711 Å (X = Br), but no Au-Au contacts were observed. Compound 3 on the other hand crystallizes in the monoclinic space group P2 1 /c. The molecules are linked into strings through short intermolecular Au-Au contacts of 3.1072 Å.

The reaction of chloro(dimethylsulfide)gold(I) with (2-hydroxybutyl)diphenylphosphine (L) (racemic mixture) in dichloromethane affords high yields of the racemic chiral complex (L)AuCl. Metathesis reactions with KBr or KI, respectively, in a two-phase solvent mix­ ture (CH 2 CI 2 /H 2 O) lead to a conversion into the corresponding bromide and iodide complexes (L)AuBr and (L)AuI. Treatment of silver chloride with the ligand L in acetonitrile yields the analogous 1:1 adduct (L)AgCl. The compounds have been characterized by their analytical and spectroscopic data, and the structures of (L)AuCl and (L)AuBr have been determined by single-crystal X-ray diffraction. The compounds build isomorphous crystal lattices (monoclinic, P2 1 /c) in which pairs of enantiomers (R-and S-configuration of L) are aggregated by two long hydrogen bonds between the hydroxyl group of the ligand and the halogen substituent of the neighbouring molecule. Cationic, linear two-coordinate 1:2 complexes (L) 2 Au + X - (X = BF 4 , CIO 4 , SO 3 CF 3 ) and (L) 2 Ag + X - (X = BF 4 ) are obtained in good yields by reaction of L with Me 2 SAuCl and AgX (molar ratio 2:1:1) or with AgBF 4 (molar ratio 2:1), respectively. 31 P NMR studies at variable temperature show an equilibrium between all possible stereoisomers (RR, SS, RS, SR) in solution with rapid ligand exchange at ambient temperatures.

[Ti 3 Cl 8 (NPMe 3 ) 3 ]Cl has been prepared by the reaction of TiCl 3 (THF) 3 with Me 3 SiNPMe 3 in dichloromethane forming green moisture sensitive crystals. According to the crystal structure determination the titanium atoms of the cation [Ti 3 Cl 8 (NPMe 3 ) 3 ] + are linked by two μ 3 -N atoms of two NPMe 3 - groups forming a distorted trigonal-bipyramidal arrangement. The third NPMe 3 - group and two of the chlorine atoms have μ2-bridging functions. The mixed-valence complex [V 2 Cl 4 (NPPh 3 ) 3 ] is formed as dark green moisture sensitive crystals by the reaction of vanadium trichloride with Me 3 SiNPPh 3 in boiling toluene. According to the crystal structure determination the vanadium atoms are linked by two μ 2 -N atoms of two NPPh 3 - groups forming a nonplanar V 2 N 2 four-membered ring with a V-V distance of 266.8(1) pm which corresponds to a (σ, 1/2π) bond type. This is confirmed by the measurement of the magnetic susceptibility which leads to a magnetic moment of 1.45(5) B. M., corresponding to the remaining d 1 -electron.

The bromosilanes RMe 2 SiBr (R = Me, Et, n-Pr and i-Pr) form ionic 1:1-compounds with N-trimethylsilylimidazole (NTMSI), stable at room temperature. Crystals of the compounds with R = Et, n-Pr and i-Pr are obtained by sublimation. From the product of the reaction of 1,1-dibromosilacyclopentane with NTMSI single crystals of N,N′-bis(trimethylsilyl)imidazolium-bromide (R = Me) were obtained. In the new adducts both silicon atoms are tetracoordinated.

The reaction of CuI or Lil with Cdl 2 in the polar solvent acetonitrile results in the formation of the iodocadmates [Cu(CH 3 CN) 4 ] 4 [Cd 6 I 16 ] · 1.5CH 3 CN (1) and [Li(CH 3 CN) 4 ] 4 [Cd 6 I 16 ] · 1.5CH 3 CN (2) with the oligomeric anion [Cd 6 I 16 ] 4- . This new type of halometallate anion, which is found in both isotypic structures, is built up by six alternating corner and edge sharing Cdl 4 tetrahedra. 1: Space group P1̄ (No 2), a = 838.5(4), b = 1465.9(9), c = 1929.8(6) pm, α = 93.01(3), β = 99.13(3), γ = 105.11(3)°; 1: Space group P1̄(No 2), a = 841.7(8), b = 1470(9), c = 1945.5(9) pm, α = 93.27(5), β = 99.13(5), γ = 104.83(5)°.

Reaction of nickel(II) chloride with disodium ο-xylenediselenolate in methanol yields the trinuclear mixed selenide-selenolate complex anion [Ni 3 Se(ο-C 6 H 4 {CH 2 Se} 2 ) 3 ] 2- (3) which was isolated both as tetramethylammonium and mixed sodium/tetraethylammonium salt of formula [Me 4 N] 2 [Ni 3 Se(ο-C 6 H 4 {CH 2 Se} 2 ) 3 ] · MeOH (1) and [Et 4 N] 3 Na[Ni 3 Se-(ο-C 6 H 4 {CH 2 Se} 2 ) 3 ] 2- · 3MeOH · 3H 2 O (2), respectively. Crystals of 1 are triclinic, space group P1̄, a = 9.065(2), b = 13.281(3); c = 18.019(4) Å , α = 92.81(2), β = 97.55(2), γ = 105.09(2)° and Z = 2. 2 crystallizes in the rhom bohedral space group R3c with a = 20.305(5), c = 41.709(9) Å and Z = 6. The structures were refined to R = 0.0705 (1) and 0.0794 (2), respectively. Both compounds contain the complex anion [Ni 3 Se- (ο-C 6 H 4 {CH 2 Se} 2 ) 3 ] 2- (3), which possesses the same principal structural features as the corresponding thiolato derivatives. Reaction of nickel(II) chloride with sodium iso-propane selenolate in methanol leads to the cyclic tetranuclear complex [Ni 4 (Se i C 3 H 7 ) 8 ] (4), which crystallizes in the monoclinic space group P2/n with a = 13.161(3), b = 10.464(2), c = 14.603(2) Å , β = 94.42(1)° and Z = 2. The structure refinement converged to R = 0.0541. 4 is isostructural with the corresponding thiolato compound. The introduction of selenium instead of sulfur ligands reduces the midpoint potential of the reversible metal-centered oxidation from +595 to +285 mV.

Upon heating 1,3,5-trimethylbiuret (1) with trichloromethyldichlorophosphine in the presence of triethylamine, 2-trichloromethyl-1,3,5-trimethyl-1,3,5-triaza-2σ 3 λ 3 -phosphorine-4,6-dione (2) was obtained in good yield. Aside from NMR spectroscopic characterization, compound 2 was investigated by X-ray crystal structure analysis, representing the first case of the solid state characterization of a 2-trihalomethyl-1,3,5-trimethyl-1,3,5-triaza-2σ 3 λ 3 -phosphorine-4,6-dione derivative. The heterocycle presents an envelope conformation with phosphorus out of the plane of the other atoms. Reaction of the monochloromethyl derivative (3) corresponding to 2, with a sterically demanding azide led by oxidation of phosphorus to the stable σ 4 λ 5 -P derivative (4). 2-Hydro-1,3,5-trimethyl-1,3,5-triaza-2-oxo-2σ 4 λ 5 -phosphorine-4,6-dione (5) reacted with p-nitrobenzylidene benzylimine with formation of 6 by insertion of the C=N double bond of the imine into the P-H bond. Intramolecular hydrogen bonding in 6 was observed by 1 H NMR and IR spectroscopy. Reaction of 2-(methylamino)-methyl-1,3,5-trimethyl-1,3,5-triaza-2-oxo-2σ 4 λ 5 -phosphorine-4,6-dione (7) with diethylamino-trimethylsilane led to the corresponding N-trimethylsilylated compound 8. Compound 9. bearing a peptoid group, was formed by reaction of 7 or 8 with 3-(chloroformyl)propionic acid methyl ester. The preferred method of synthesis of 9 is indicated.

We determined the decomposition equilibria of ammonium samarium chlorides (NH 4 ) 2 SmCl 5 and NH 4 Sm 2 Cl 7 by total pressure measurements and derived their thermody­ namical data from the decomposition functions. The enthalpies of formation were compared with the results of the solution calorimetry. The heats of solution of all solid phases in the system SmCl 3 -NH 4 Cl and of Sm 2 O 3 were measured in 4n HCl. The enthalpies of formation of ammonium samarium chlorides were derived from the enthalpies of formation of SmCl 3 and of NH 4 Cl and their heats of solution. Data by total pressure measurement ΔH° B ((NH 4 ) 2 SmCl 5,f,298 ) =-407,7 ± 2,9 kcal/mol; S0((NH 4 ) 2 SmCl 5,f,298 ) = 84,0 ± 4,5 cal/K-mol; ΔH° B ((NH 4 )Sm 2 Cl 7,f,298 ) = -576,8 ± 3,4 kcal/mol; S°(NH 4 Sm 2 Cl 7,f,298 ) = 98,1 ± 5,5 cal/K-mol. Data by solution calorimetry ΔH° B (SmCl 3,f,298 ) = -248,1 ± 0,8 kcal/mol; ΔH° B ((NH 4 ),SmCl 5,f,298 ) = -404 ,3 ± 1,1 kcal/mol; ΔH° B (NH 4 Sm 9 Cl 7,f,298 )= -572,3 ± 1,8 kcal/mol.

Pyrimidine-diones, Caffeine Metabolites, Synthesis 5-Acetylamino-6-amino-3-methyluracil (AAMU) and 5-acetylamino-6-formylamino-3-methyluracil (AFMU) have been prepared by simple chemical transformations starting from thiourea and ethyl cyanoacetate. These compounds AAMU and AFMU are required as standard materials for qualitative identification and quantitative determination in connection with the metabolism of caffeine.

The synthesis and mesomorphic behaviour of new series of liquid crystals containing 1,3,4- thiadiazole and thiophene rings with azo central bond are reported (series 5a and 5b). All compounds of series 5a exhibit enantiotropic nematic mesophase and the higher homologues (n = 9 - 10) also show a monotropic smectic C phase. Series 5b show dimorphism S C - N (for n = 5 - 7 the S C is monotropic). These series are compared with the Schiff’s bases analogues, the imine bond gives rise to similar liquid crystals phase but larger mesomorphic range.

, 1997 1,3,5-Triphenylbenzenes, Chiral and Non-Chiral Substituents Aiming to design new discotic liquid crystals, chiral and non-chiral esters and ethers of hexa-and nonasubstituted 1,3,5-triphenylbenzenes were synthesized. The new compounds are crystalline or high viscous liquids. They do not form mesophases or columnar donor-acceptor-complexes with TNF, DNF or DBox-H. The chiral esters 5c and 5d. used as dopants, induce cholesteric phases in nematic discotics.

Though diphenyl 1,1-diarylsubstituted phosphonates are known for a long time, FAB-mass spectrometry and X-ray crystal analysis revealed that these species occur as dimers in the solid state and in the gas phase.

(PPN) 2 C 16 S 18 was obtained by the addition of PPN + Cl - to a methanolic extract of Na 2 C 4 S x , derived from the reaction of C 6 S 8 O 2 and NaOMe. Centrosymmetric C 16 S 18 4- consists of thiophene units unsymmetrically fused to two 1,4-dithiin rings. Solutions of C 16 S 18 4- convert to C 8 S 8 2- with heating. When C 4 S x (x ~ 8) is reduced by Na/NH 3 followed by extraction and crystallization, one obtains the bicyclic polysulfide C 4 S 8 2- , crystallized as its PPh 4 + salt.