Volume 44, Issue 5

The quasibinary system Naln-Sn contains the intermediate phases Na y In y Sn, Na 9 In 9 Sn 2 , NalnSn, Na 2 In 2 Sn 3 , NaInSn 2 and NaInSn 4 . With the exception of Na 2 In 2 Sn 3 (stable only between 134°C and 365°C), crystals of the ternary compounds were grown from the melt and were investigated by single crystal X-ray methods (Na 9 In 9 Sn: a = 2287.7(8) pm, F43m; Na 9 In 9 Sn 2 : a = 1662.4(7), c = 983.9(5) pm, P6/mmm; NaInSn: a = 486.1(2), c = 775.7(4) pm, P6 3 /mmc; NaInSn 2 : a = 627.9(3), b = 654.3(3), c = 1139.6(5) pm, P2 1 2 1 2 1 ; NaInSn 4 : a = 654.6(4), c = 531.6(6) pm, I4/mcm). The crystal structure of NaInSn is a representative of the Zintl-phases. with the [InSn]⁻-partial structure in a wurtzite-type arrangement. The crystal structures of NaInSn 4 and NaInSn 2 have been determined (R = 0.038 and 0.062, respectively). The crystal structure of NaInSn 2 contains In and Sn atoms in a helical arrangement (six atoms per turn) along the α-axis direction. Interatomic bonds between neighbouring helices complete a distorted [2+2]-tetrahedral environment for every In/Sn position. The compound can be classified in terms of the Zintl concept. NaInSn 4 is an isotype of the intermetallic phase Al 2 Cu. By this, the chemical and structural series NaInSn → NalnSn 2 → NaInSn 4 represents a change from Zintl-phases to an intermetallic phase.

Exhaustive reductive silylation of 2-trimethylsilyl-1,2,3-triazole (1) using Me,SiCl/K yields the new E-1,1,4,4-tetrakis(trimethylsilyl)-l,4-diazabutene(2) (4) as final product together with N(SiMe 3 ) 3 . Initial reductive 1,4-addition to 1 leads to formation of 1.2.3-tris(trimethylsilyl)-1,2,3-triazoline(4) (2) as an intermediate which is rapidly reduced and silylated further to give the butene 4. Partial π overlap within the five-membered ring 2 containing 8 π electrons and three neighbouring unshared electron pairs is evident from NMR shifts and electron transfer reaction with TCNE. Photoelectron spectroscopy of 4 and the lability of its radical cation 4 +. as studied by ESR show that this system cannot adopt a planar conformation in contrast to the tetrazene(2) analogue.

By reaction of methanolic solutions of hexamethylenetetramine with aqueous solutions of hexacyanoferrates(III) of strontium and barium resp., crystals of the compounds were obtained. Sr 3 [Fe(CN) 6 ] 2 · 3 C 6 H 12 N 4 · 18 H 2 O, tetragonal, space group P4 2 /nmc, Z = 4, a = 1931.8(4), c = 1579.9(4) pm, 1358 reflections. R = 0.066. Ba 3 [Fe(CN) 6 ] 2 · 2 C 6 H 12 N 4 · 11 Η 2 Ο. monoclinic. space group P2 1 /n, Ζ = 2, a = 1148.0(4), b = 1369.7(4), c = 1584.5(4) pm, γ = 95.79(3)°, 2583 reflections, R = 0.057. The crystal structures of these adducts are compared with those of other hexamethylenetetramine adducts of alkaline and alkaline earth metal hexacyanoferrates of the general formula M,[Fe(CN) 6 ] y · zC 6 H 12 N 4 · vH 2 O recently investigated by us. A structural model for the adducts is presented.

Hydrophilic sulfur sols prepared by reaction of aqueous sulfide and sulfite at low pH have been studied by chemical analysis, ion-pair chromatography, and reversed-phase HPLC. The approximate composition of the sol is x(NaHSO 4 /Na 2 SO 4 ) ·yS n · zNa 2 S m O 6 with n = 6-10 and m = 4-16. The elemental sulfur S n accounts for 17% and the polythionate sulfur for 10% of the dry weight (sulfate: 18%). On aging of the sol at 20°C the long-chain polythionates decompose to elemental sulfur and tetrathionate as well as pentathionate. The higher chemical reactivity of this sol compared to S 8 is explained by the fact that 45% of the zero oxidation state sulfur (S°) are present as non-S 8 molecules.

[η 5 -CpMCl 4 ] (M = Nb, Ta) reacts with E(SiMe 3 ) 2 (E = S, Se) to form different multinuclear clusters. The cation [Cp 8 Ta 6 S 10 ] 2+ (1) consists of a planar Ta 2 S 2 -ring of which each Ta is coordi-nated to two Cp 2 TaS 2 -fragments. [Cp 4 Ta 4 S 13 ] (3) can be derived from [Cp 3 Ta 3 S 7 Cl 2 ] (2) by addition of a CpTaS 6 -unit to a triangle of Ta-atoms bridged by S- and S 2 -ligands. The niobium atoms in [Cp 3 Nb 3 Se 5 Cl 2 ] (4) arrange in a chain structure with Nb coordination numbers varying from 4-6.

The acidity constants of H(R-MP) - , where R-MP 2- = 4-nitrophenyl phosphate (NPhP 2- ), phenyl phosphate (PhP 2- ) and D-ribose 5′-monophosphate (RibMP 2- ), and the stability constants of the binary Cu(R-MP) complexes were determined by potentiometric pH titrations in aqueous solution and in 20, 30, 40 and 50% (v/v) dioxane-water mixtures. The solvent influence on the corresponding equilibrium constants is compared with the same influence on previously studied systems containing uridine 5′-triphosphate, formate or acetate. The influence of the solvent composition on the various ligand (L) systems was evaluated by constructing log KM (L) versus pK H(L) H plots; in all cases straight lines are obtained with slopes close to 1. This indicates that in all these systems, despite the different negative charges of the involved ligands, the solvent effect on proton binding and on metal ion binding is approximately of the same size: A decreasing solvent polarity resulting from the addition of increasing amounts of organic solvent to the aqueous solutions favors the affinity of the negatively charged ligands for protons and metal ions as well. Information of this type is considered important because the ‘effective’ or ‘equivalent solution’ dielectric constants in active-site cavities of enzymes are reduced compared with the dielectric constant of bulk water; i. e., in protein cavities also a decreased ‘solvent polarity’ is occurring and this is expected to affect the stability of metal ion-ligand bonds.

The reactions of 1,1,2,2-tetrafluoroethane-1,2-bisulfenyl-chloride 1 and symmetrical azines 2 yield the conjugated trans-diazenes 3 as deep-coloured solids. Unsymmetrical azines 4 react with 1 under elimination of hydrogen chloride to give 1,3-dithiolane-substituted azine derivatives as pale-coloured liquids. The crystal structure of 3b has been determined by single crystal X-ray diffraction. A participation of the phenyl group in the conjugated system is not observed in 3b.

2-Trimethylsilyl-1,3-bis-trimethylsilylimino-1,3-dihydro-isoindole, C 8 H 4 N 3 (SiMe 3 ) 3 (2), has been prepared by the reaction of 1,2-benzodinitrile with LiN(SiMe 3 ) 2 , followed by treatment with ClSiMe 3 . 2 forms yellow crystals, which were characterized by a crystal structure determination, as was the known hexakis(trimethylsilyl)-1,4-benzdiamidine, {[(SiMe 3 ) 2 N](SiMe 3 N)C-C 6 H 4 -C(NSiMe 3 )[N(SiMe 3 ) 2 ]}) (1). 1: space group P1, Z = 1̄,2520 observed independent reflexions, R = 0.052. Lattice dimensions (19°C): a = 662.7(1); b = 1088.3(1); c = 1417.4(2) pm; α = 76.60(1)°; β = 87.33(1)°; γ = 73.90(1)°. 1 forms monomeric centrosymmetric molecules with the amidino groups in 1,4-position of the C 6 H 4 ring. The CN distances are 127.1(3) and 141.3(3) pm, respectively, corresponding to C=N̅-SiMe 3 and C-N̅(SiMe 3 ) 2 moieties. 2: space group P2 1 2 1 2 1 , Z = 4, 1960 observed independent reflexions, R = 0.058. Lattice dimensions (20°C): a = 643.0(1); b = 1477.4(1); c = 2414.4(2) pm. 2 forms monomeric molecules with a planar isoindole skeleton with different Si-N-bond lengths of the SiMe 3 groups in 2-position (180.2(5) pm) and in 1,3-positions (171.4(5); 170.9(9) pm).

Single crystals of Cu(pz)Br 2 and Cu(pz)Cl 2 were grown by using gel methods with tetramethoxysilane as the gel-forming reagent. Thermal decomposition is interpreted. Crystal data for the bromo complex: monoclinic, space group C2/m with a = 1239.2(3) pm, b = 685.9(2) pm, c = 390.7(3) pm, β = 96,23(5)°. Crystal data for the chloro-complex: monoclinic, space group C2/m with a = 1197.1(3) pm, b = 684.9(3) pm, c = 370.1(3) pm, β = 95.96(5)°. Crystal structure analyses reveal that CuHal 2 molecules are bonded by pyrazine to form linear chains. These chains are cross-linked by bridging halogen atoms.

The emission spectra (at T = 10 K and 296 K) and the excitation spectra (at T = 295 K) of zeolite-based luminophores of the types Zn 2 SiO 4 :Mn and (CdO) 2 B 2 O 3 :Mn show the characteristics of Mn 2+ in tetrahedral and octahedral surroundings, respectively, as well as additional features due to impurities and/or structural defects of the host crystal. The ZnSiO 4⁻ type phosphor exhibits photostimulated emission, which can be assigned to trap states of the silicate host.

Reaction of Et 3 As with AsCl 3 in n-pentane yields dimeric [Et 3 AsxAsCl 3 ] 2 in quantitative yield; sublimation in vacuo affords white crystals. X-Ray diffraction data were collected at 133 K (3149 independent observed reflections; R = 0.029. R w = 0.026). Crystal data: monoclinic space group P2 1 /c, a = 761.9(8). b = 1118.8(4). c = 1406.0(14) pm; β = 100.90(4)°. Ζ = 2 dimers. The dimer contains a planar As 2 Cl 6 -unit with terminal and bridging As-Cl bonds; each arsenic atom is bonded to a Et 3 As molecule via an arsenic-arsenic bond. The dimer thus has pseudo four- and six-coordinate arsenic atoms.

The alkyl N-benzyl-4-piperidone-3-carboxylate (1) is synthesized by a Mannich procedure from pyridine aldehyde, benzylamine and the monoester of acetonedicarboxylate; the corresponding diester 2 is formed by condensation of pyridine aldehyde, benzylamine and dimethyl 3-oxoglutarate. Isomerism is observed with respect to keto-enol tautomerism and cis or trans substitution of the pyridines. The structure of the enol lb (C 24 H 23 N 3 O 3 ) is determined by X-ray analysis: it crystallizes in the triclinic space group P 1̄ with a = 9.965(2), b = 10.476(2), c = 10.838(2) Å, α = 69.48(1), β/3 = 81.56(1), γ = 79.09(1)°, Ζ = 2 and D x = 1.29 g cm -3 . It is refined to R(unweighted) = 0.047 and R(weighted) = 0.045 using 1459 non-equivalent reflections. The structures of la/b and 2a/b were determined by 1 H and 13 C NMR data. MNDO calculations of 1a/b are discussed. The enols 1/2b are reduced by sodium borohydride. The configuration of the obtained alcohols is determined by NMR data.

The crystal and molecular structure of [NP(OC 10 H 7 ) 2 ] 3 was determined by X-ray analysis. The dipole moments of this compound and of the hexa(phenoxo)cyclotriphosphazatrienes of formula [NP(OC 6 H 3 XX′Y) 2 ] 3 (X = X′ = H, Y = p-Br; X = m-CH 3 ,. X′ = H. Y = p-Cl; X = X′ = m-CH 3 , Y = p-Cl; X = X′ = m-CH 3 , Y = H; X = X′ = H, Y = p-CH(CH 3 ) 2 ; X = X′ = H, Y = p-C(CH 3 ) 3 ) were measured in benzene at 25°C. Crystals of [NP(OC 10 H 7 ) 2 ] 3 are monoclinic with unit cell dimensions a = 24.870(15), b = 7.712(8), c = 27.687(14) Å, β = 115.85(7)°; space group P2 1 /c. The structure was refined to an agreement factor of 0.09. The phosphazene ring deviates (max. deviation 17°) from planarity. and mean distances (A) and angles (°) are P-N 1.58(1). P-O 1.58(1), O-C 1.41(2); P-N-P 120(1), N-P-N 119(1), P-O-C 124(2). The conformations of the naphthyloxo groups at P(2) and P(3) are similar, and different from the group at P(1). Dipole moment analysis showed that the solid state conformation changes in the solution state. The measured value was in agreement with a symmetric conformation in which at the O-P-O plane each naphthyloxo group is rotated by ca. 40-50° from the anti-coplanar arrangement relative to this plane. The dipole moment data for the p-substituted phenoxo derivatives agree with such a conformation, but the analysis of the dipole moment values of phosphazenes having phenoxo groups bearing more than one substituent group and p-CH(CH 3 ) 2 substituent failed to do so due to the inherent limitations of the method.

A critical evaluation is presented of the scope of amination reactions with O-diphenylphosphinylhydroxylamine (ODPH) as compared to those using hydroxylamine-O-sulfonic acid (HOSA). Aminations with ODPH of isopropyl, t-butyl and cyclohexyl carbanions derived from the corresponding Grignard reagents, gave the corresponding amines in 36, 34 and 50 percent yields, respectively. The amination with HOSA of the same carbanions under similar conditions was unsuccessful. The aminative quarternization of the tertiary nitrogen of pyridine and quinoline with ODPH proceeded with comparable yields to those obtained with HOSA. An improved one flask amination with ODPH of indole, skatole and carbazole was achieved in 52-62 percent yields. The amination under the same conditions using HOSA gave consistently lower yields. Several other amination reactions which have been reported for HOSA were unsuccessful using ODPH. The conclusion is reached that overall the ODPH reagent is much less versatile than HOSA. Nevertheless, in the aminations of NH groups of heterocyclic compounds ODPH appears to be superior to HOSA and is the reagent of choice, in particular, since the preparation of ODPH is much less harzardous than that of HOSA.

Reaction of 2.2-diethoxy-1-ethenediazonium salt la with primary amines 5 yields 1-alkyl-1 H1,2,3-triazoles 7. With hydrazide 8 diazonium salt la reacts completely differently. The thus formed 2′-[2-phenyl-4H-1,3,4-oxadiazine-5(6H)-ylidene]benzohydrazide (9) can be annellated under elimination of water or transformed by reaction with phosgene, thionyl chloride and phthalic acid dichloride respectively to give the heterocycles 10-13.

The temporal degradation of the Belousov-Zhabotinskii substrates lactic acid, pyruvic acid, bromo- and dibromo pyruvic acid is investigated. The only final product of non-brominated substrates is acetic acid. From brominated educts only brominated acetic acids result. The concentrations of the stable products are determined as a function of time. The gross reactions are mainly based on simple consecutive first order reactions. For the pyruvic acid rate constants are determined.

The tetrabromophosphate(III) anion in [Et 4 N][PBr 4 ] displays an extremely distorted Ψ-trigonal bipyramidal structure with axial P-Br distances of 2.970(2) and 2.305(2) Å. A structural correlation of bond distances in characterized halogenophosphates(III) indicates that such an asymmetric three-centre Br-P ··· Br interaction represents an energy minimum for isolated anions.

Hexachlorocyclotriphosphazene (Cl 2 P=N) 3 reacts with dihydrazidothiophosphoric acid 0-phenylester C 6 H 5 O—P(=S)(NH—NH 2 ) 2 in THF in the presence of triethylamine at room temperature to give the spirocyclic title compound, whose constitution has been confirmed by MS, IR, 31 P NMR and elemental analysis.

The unit cell of (R*,R*)-(±)-[(η 5 -C 5 H 5 ){1.2-C 6 H 4 (PMePh) 2 }Fe(PCl 3 )]Cl · 2 MeCN is orthorhombic, space group Pccn, with a = 1531.2(3). b = 2202.7(20). c = 1874.6(16) pm, and Z = 8. The salt crystallizes as a racemic compound with four pairs of asymmetric cations of opposite helicity and associated anions and solvent molecules in each unit cell.