Volume 49, Issue 10

The ternary stannides RE 2 Au 2 Sn (RE = Y, Dy, Ho, Er, Tm, Lu) were prepared by arcmelting of the elemental components and subsequent annealing at 800 °C. The structure of Er 2 Au 2 Sn (single crystal, X-ray, P4 2 /mnm, Z = 4, a = 778.2(2) pm, c = 739.6(3) pm, V = 0.4479 nm 3 and R = 0.026) is described as the ternary ordered version of the Zr 3 Al 2 -type structure, a superstructure of the U 3 Si 2 -type. It consists of two-dimensionally infinite layers (Au 2 Sn) n which are separated by the erbium atoms. The structure is built up from slightly distorted [SnEr 8 ) square prisms and [AuEr 6 ] trigonal prisms which are condensed in all three directions. These fragments are derived from the well known AlB 2 and CsCl-type structures.

The reaction of triorganolelluronium chlorides R 3 TeCl (R = Me, Ph, 4-tBu-C 6 H 4 ) with Na 2 S x , (x = 4 - 6) yields the corresponding bis(triorganotelluronium) hexasulfides (R 3 Te) 2 S 6 regardless of the employed sodium polysulfide or the size of the lelluronium cation. All compounds are thermally stable and insensitive to moisture or air. (Ph 3 Te) 2 S 6 was structurally characterized by X-ray crystallography (monoclinic, space group P2 1 /c). Each tellurium atom is connected to both ends of the hexasulfide chain.

The reactions of (Ph 3 Sn) 2 O with PhMePOCl and with Ph 2 POCl lead to Ph 3 SnO 2 PMePh and Ph(SnO 2 PPh 2, respectively. Ph 3 SnO 2 PMe 2 has been prepared from the reaction of (Ph 3 Sn) 2 O and Me 2 PO 2 H in toluene. The IR and Raman spectra of Ph 3 SnO 2 PMe 2, Ph 3 (SnO 2 PMePh and Ph 3 SnO 2 PPh 2 are found to be consistent with polymeric structures with pentacoordinated tin atoms. The EI mass spectra indicate that the principal fragmentation processes of Ph 3 SnO 2 PRR′ (RR′ = Me 2, MePh, Ph 2 ) appear to occur by loss of phenyl radicals from tin and by elimination of the entire diorganophosphinate group.

The bipyridyldiacetylene 6,6′-(CH 3 CH 2 CH 2 C = C) 2 bpy (1) was prepared by palladium catalyzed C - C - coupling reaction of 6,6′-dibromo-2,2′-bipyridine with pentyne. Reaction of 1 with anhydrous CuCl 2 in acetonitrile gave the dimeric, chloro-bridged complex (1)Cu(Cl)(µ-Cl) 2 Cu(Cl)(1) (2), which was characterized by X-ray crystallography. The copper atoms in 2 are square-pyramidally coordinated with normal in-plane Cu - N and Cu - Cl bond distances and one longer, apical bond to the second bipyridyl nitrogen atom. The influence of steric hindrance of the bipyridyl 6,6′-substituents on the structure of the complex is discussed.

Single crystals of NaMg 1.64 Cu 0.36 V 3 O 10 have been prepared by heating mixtures of Na 2 CO 3 , MgCO 3 , CuO and V 2 O 5 above the melting point. The yellow crystals show triclinic symmetry, space group C i 1 -P1̅, a = 6.726(8), b = 6.743(7), c = 9.625(2) Å, α = 100.705(9), β = 104.57(1), γ = 101.700(9)°, Z = 2. NaMg 1.64 Cu 0.36 V 3 O 10 represents a new structure type showing V 3 O 10 groups, a statistical distribution of Mg 2+ and Cu 2+ on two point positions, and Na + in an irregular coordination.

The crystal structure of Mg(IO 3 ) 2· 4H 2 O has been determined by neutron single crystal diffraction (P2 1 /c, Z = 2, R = 2,2% on the basis of 1107 observed reflections). Mg(IO 3 ) 2· 4H 2 O forms a layered structure built up of octahedral Mg(H 2 O) 4 (IO 3 ) 2 units linked by hydrogen bonds. The two crystallographically different water molecules are in­ volved in asymmetric, nearly linear hydrogen bonds to adjacent iodate ions (ν OD of matrix isolated HDO: 2480, 2475, 2425 und 2412 cm -1 , IR spectroscopic data, 90 K). The strength of the hydrogen bonds as well as that of other iodate hydrates is discussed in terms of both the synergetic effect and Brown’s bond valences.

The one-electron transfer to large π-delocalized hydrocarbons provides an interesting possibility to crystallize solvent-separated ion-pair salts containing optimally solvated cations. Accordingly, the reduction of 9.9′-bianthryl in aprotic 1.2-dimethoxyethane (DME) solution at a sodium metal mirror allows to grow dark blue, brick-like crystals of its radical anion and threefold DME-solvated sodium cation. The structure of the radical anion is very similar to that recently published for the neutral molecule. According to AM 1 enthalpy hypersurface calculations based on the structural data, the torsion angle between 60° and 120° is determined by the lattice packing and the negative charge is -π-delocalized predominantly within only one anthracene subunit. The counter cation [Na⊕(DME) 3 ], reported only three times so far, shows a sixfold propeller-like coordination of approximate D 3 skeletal symmetry with contact distances Na⊕···O between 232 and 243 pm and angles ≮ONa⊕O varying between 69° and 159°. Due to the small repulsion between the chelating DME molecules, the isodesmically calculated Na⊕ solvation enthalpy is more negative than that of the analogous tetrahydrofuran complex [Na⊕(THF) 6 ] - as confirmed by the laboratory experience that salts of less stable anions are preferentially crystallized from a strongly cation solvating DME solution.

Disilylacetylene (1) has been obtained from LiAlH4 reduction of bis(trichlorosilyl)acetylene (2) and bis[(trifluoromethylsulfonyloxy)silyl]acetylene (4). The catalytic hydrosilylation of 2 with HSiCl 3 affords tris(trichlorosilyl)ethene (5) and 1.1.2-tris(trichlorosilyl)ethane (6). The synthesis of 6, trans-bis(trichlorosilyl)ethene (8) and 1,1-bis(trichlorosilyl)ethene (9) has been accomplished by hydrosilyiation of trichlorosilylacetylene (7) which was synthesized by the reaction of trichloro(trifluoromethylsulfonyloxy)silane with sodium acetylide. Reductive elimination of halogen from 1,1,1,2-tetrachloro-bis(trichlorosilyl)ethane (10) and 1,2- dibromo-1,1-bis(trichlorosiIyl)ethane (13) gave the corresponding ethenes 1,1-dichloro-bis- (trichlorosilyl)ethene (11), trichloro-trichlorosilylethene (12), 1,1-bis(trichlorosilyl)ethene (9) and 1-chloro-2,2-bis(trichlorosilyl)ethene (14). Tetrakis(trichlorosilyl)ethene (15) has been obtained in a three step synthesis starting from chloromethyl-trichlorosilane or dichloro- methyl-trichlorosilane. By LiAlH 4 reduction of trichlorosilylethenes under various reaction conditions, the silylethenes trans-dichloro-di(silyl)ethene (16), 1,1-dichloro-di(silyl)ethene (17), trichloro-silylethene (18), 1-bromo-l-silylethene (19), trans-di(silyl)ethene (20), 1-chloro-2,2-di(silyl)ethene (21), tri(silyl)ethene (22) and 1,1,2-tri(silyl)ethane (23) could be generated. Silylethyne and silyl-chloroethyne were identified as side products. The crystal and molecular structures of 2,5 and 15 have been determined by single crystal X-ray diffraction. 2 and 5 crystallize from the melt in the monoclinic space groups Cc and P2 1 /n, respectively. 15 has been crystallized by sublimation (orthorhombic. space group Pbca). 5 and 15 feature strongly distorted ethene skeletons with a double bond twist of 28.1° in 15.

A simple route to 1,3-diphosphetanes [RPCF 2 ] 2 [R = Ph, Me, Bu t ] is described. The phosphaalkene intermediates RP=CF 2 , as well as the corresponding disulfides [R(S)PCF 2 ] 2 have been characterized. The crystal structures of [PhPCF 2 ] 2 , and of the sulfides [Ph(S)PCF 2 ] 2 and [Bu t (S)PCF 2 ] 2 are reported.

The new complex carbonate Rb 2 [Mg(CO 3 ) 2 (H 2 O)) 4 ] crystallizes in the Baylissite-type structure with a = 1130,4(3), b = 641,9(1), c = 703,3(2) pm, β = 99,62(1)°, V EZ = 503,2(2), space group P2 1 /n (No. 14) and Z = 2. In comparison with the isostructural potassium compound the cell dimensions increase in b- and c- and decrease in a-direction. This effect depends on the greater coordination number of Rb + and the rigidity of strong hydrogen bonds. The carbonate anion exhibits significant deviations from D 3h -symmetry (C -O: 127,1(5)-130,2(5) pm, ∠ O - C - O: 117,9(4)-121,1(3)°).

Single crystals of the cyano complexes [N(CH 3 ) 4 ] 2 CsCo(CN) 6 and [H 3 NCH 3 ] 2 NaFe(CN) 6 were prepared and their structures determined by X-ray methods. The cobalt compound is monoclinic, a =885.5(1), b = 892.6(2), c = 1259.9(5) pm, β = 90.29(4)°, space group I2/m, Z = 2; R1 = 0.048 for 861 independent reflections. The resulting average distances in the nearly undistorted octahedra are Co - C = 189.8, C - N = 114.1, Cs - N = 325.6 pm. The iron compound exhibits a cubic elpasolite type structure, a = 1105.2(1) pm, space group Fm 3m , Z = 4; R1 = 0.040 for 127 independent reflections; Fe - C = 193.4(6), Na - N = 247.7(8) pm. The orientation of the librating tetramethyl-ammonium group within the cages of the cobalt compound and the disorder of the monomethyl-ammonium cation around the special site (1/4, 1/4, 1/4) of the iron complex are discussed.

The title compound has been prepared starting from phosphorothionic triamide SP(NH 2 ) 3 by methylation of the sulfur atom and subsequent ammonolysis reaction in dry acetonitrile and dichloromethane, respectively, both at room temperature. Suitable single crystals are obtained from an acetonitrile solution in a temperature gradient between 70 °C and room temperature. The crystal structure of [P(NH 2 ) 4 ]I has been determined by single crystal X-ray methods (P4/nbm; a = 842.6(2), c = 486.7(2) pm, Z = 2). In the solid [P(NH 2 ) 4 ] + - and I − -ions are found with significant N - H···I-hydrogen bonding interactions between anions and cations (H -I: 276.4 pm). The P - N - bond length in the cation (160.7(2) pm) represents the shortest P - NH 2 bond distance reported to date indicating a significant electrostatic strengthening. The condensation behaviour of [P(NH 2 ) 4 ]I in solution and in the solid has been investigated.

Ternary phases Ta 1-x Mo x S 2 with 0.25 ≤ x ≤ 0.55 have been investigated regarding their intercalation potential using pyridine as guest molecule. Intercalation yields hexagonal phases Ta 1-x Mo x S 2 ·(pyridine) n . The different phases have been characterized by elemental analysis as well as TGA and powder diffraction patterns, which have been indexed using the space group P3m1. For the compound Ta 0.65 Mo 0.35 S 2 ·(pyridine) 0.38 a structural model was developed, based on powder diffraction data: P3m1, a = 3.275(2), c = 12.008(7)Å and Z = 1. During intercalation the stacking sequence of the host lattice is changed from BaB/AcA/CbC to BaB(pyr)/BaB(pyr). Intercalation of pyridine into Ta 1-x Mo x S 2 proceeds via a two-step mechanism. In the first step orthorhombic phases are formed with reduced pyridine content as compared to the final intercalation product; e.g. Ta 0.55 Mo 0.45 S 2· (pyridine) 0.38. The first step intercalation compounds can be obtained by interruption of the intercalation reaction after 7 days.

The diyne complexes [(Et 2 S)WCl 4 (R-C≡C-(CH 2 ) n -C≡C-R)WCl 4 (SEt 2 )] (R = SiMe 3 , n = 3, 4, 8; R = C 6 H 5 , n = 4, 8) have been prepared by the reaction of trans-[WCl 4 (SEt 2 ) 2 ] with the corresponding diyne in toluene solutions. The complexes form green or orange, diamagnetic, moisture sensitive crystal powders, which were characterized by their IR and 13 C NMR spectra. The crystal structure of the complex with R = SiMe 3 and n = 4 has been determined. [(Et 2 S)WCl 4 (Me 3 Si-C≡C-(CH 2 ) 4 -C≡C-SiMe 3 )WCl 4 (SEt 2 )]: Space group P2 1 /c, Z = 2, 3620 observed unique reflections with I > 2σ(I), R = 0.027. Lattice dimensions at -70 °C: a = 1431.8(11), b = 839.6(8), c = 1731.3(11) pm, β = 112.74(2)°. The structure consists of molecules in which both tungsten atoms are surrounded by four chlorine atoms in equatorial positions, both alkyne groups are bonded side on (η2) to the tungsten atoms, whereas the sulfur atoms of the diethylsulfide molecules are located trans to the alkyne groups.

Diarylselenoketones Ar 1 Ar 2 C=Se (2b: Ar 1 = C 6 H 5 , Ar 2 = -p-C 6 H 4 Cl; 2c: Ar 1 = Ar 2 = -p-C 6 H 4 F) were generated by treatment of the corresponding ylides with elemental selenium (“Staudinger-Chalcogenation”) and trapped with 2,3-dimethylbutadiene and 3,4-bis(methylene)-1,1-diphenyl-1-germacyclopentane, respectively, to yield the substituted 2,2-diaryl-3,6-dihydro-2H-selenapyrans 5b and 5c. The compounds 5b and 5c were characterized by X-ray crystal structure analyses.

1,1′-Dibromoferrocene (1) and alkylferrocenes (ethylferrocene 2a, n-butyiferrocene 2b) react stepwise with an excess of boron tribromide in hexane to give first the monoborylated ferrocenes (3, 5a, 6a) followed by the diborylated ferrocenes (4, 7a, 8a). In the case of 4, two diastereomers are obtained. The triborylated ferrocene derivatives 9a,b are obtained in high yield as the final products. The proposed structures of all borylated ferrocenes are supported by a consistent set of 1 H, 13 C and 11 B NMR data.

If for a given system two-dimensional (2D) 119 Sn/ 1 H heteronuclear shift correlations can be established for long range coupling constants n J( 119 Sn, 1 H) (n = 4, 6), absolute signs of coupling constants J(Sn,Sn) are accessible by this technique for the first time. This has been demonstrated for tetrakis(trimethylstannyl)allene (1) with 2 J( 119 Sn, 117 Sn) (>0) and 4 J(Sn. 117Sn) (<0) and for tris(trimethylstannyl)phosphane (2) and bis(trimethvlstannyl)- sulfane (3) with 2 J( 119 Sn, 117 Sn) (<0).

Depolymerisation of a copper(II)/pyrrolidine-based 2D -polymer 2 by 4,4′-bipyridyl [molar ratio: 2 (CuL 2 ) : 1 (Bipy)] and recrystallisation of the reaction product leads to two visually distinguishable crystal charges, composed of dark green octahedra meso-4 and light green rod-shaped crystals racem-5. Separation of the conglomerate of the morphologically different crystals is accomplished by pick out. The structure of the dinuelear complex racem-5 has been established unambigously by X-ray structure analysis. EPR and susceptibility measurements of mixtures of complex meso-4 and racem-5 indicate that there is no interaction be­tween the two copper(II) centres.

Recently we have shown that reaction of copper(II) acetate with pyrrolidines 3 (HL 1 ) and 4 (HL 2 ) leads to the formation of the 2D-coordination polymer 1 and the helical 1 D-polymer 2. Ligands of semicorrin type 9 (HL 3-5 ) exhibit similar structural motives compared with the tridentate pyrrolidine ligands 3 and 4. Reaction of semicorrin 9a (HL 3 ) with Co(II) acetate yields the mononuclear chelate complex 10a (CoL 3 2 ), whereas in the presence of oxygen the formation of the oxidation product 14 [CoL 3 2 (OAc)] is observed. The chiral semicorrin ligands 9b, c (HL 4 , HL 5 ) react with metal(II) acetates to give the complexes 10b,c-13b,c via diastereospecific complexation. The structures of the cobalt complexes have been established by single-crystal X-ray diffraction.

The kinetics of hydrolysis of new, N G -protected 2,4,6-triisopropylbenzene-sulphonyl (6). 4-methoxy-3,5-di-tert-butylbenzenesulphonyl (12) and phenanthrene-3-sulphonyl (17) Fmoc derivatives of L-arginine (1) in comparison with commercially available Fmoc-Arg(Mtr)-OH (Mtr = 4-methoxy-2,3,6-trimethyl-benzenesulphonyl (2)) are studies. The acid lability of the arylsulphonyl group is decreasing as follows Mtr > Tip > Mtbs > Phen. The effect of electron- donating alkyl groups as substituents in increasing the acid lability of the arylsulphonyl residue seems to be in the order of methyl > isopropyl > tert-butyl while the effect of extended derealization does not appreciably increase the acid lability.

Reaction of sugar triflates (1) and (2) with tert-butyl cyanoacetate in presence of sodium hydride affords the cyclopropanated sugars (3) and (4), followed by selective hydrolysis of the ester group to free acids (5) and (6), respectively. Couplings of (5) and (6) with protected glycine and L-alanine lead to cyclopropanated sugar amino acids (7-10). The coupling of 6 with benzyl 3,4-(“exo”-aminomethyl)methano-3,4-dideoxy-β-L-arabinopyranoside (11) fur­ nished benzyl 3,4-[(C-cyano-amido)methano-(benzyl 3,4-(“exo”-methylene)methano-3,4-di-deoxy-β-L-arabinopyranosido)]-3,4-dideoxy-β-L-arbinopyranoside (12), suggesting an “exo” orientation of the ester group in 3 and 4.

The new compounds Ho 4 C 7 and Y 4 C 7 have been prepared by reaction of stoichiometric amounts of the metals and C in closed Ta capsules at 1450 and 1300 K. respectively. With HoF 3 as a flux, black, needle like single crystals of Ho 4 C 7 were obtained, which are air and moisture sensitive. Ho 4 C 7 crystallizes in the space group P2 1 /n (No. 14) with lattice constants a = 368.06(3), b = 1251.8(1). c = 1364.4(2) pm and β = 96.62(1)°. Y 4 C 7 with a = 370.08(5), b = 1258.9(1), c = 1371.8(1) and β = 96.61(1)°. Two different kinds of carbon species occur in the two structures: isolated C 4- ions and C 3 4- units, respectively. The C 4- ions are octahedrally surrounded by Ho-atoms. The Ho 6 C octahedra are condensed to form double chains parallel [100]. The chains are linked via C 3 4- ions, which occupy positions above the edges of the Ho octahedra. Additional Ho atoms are located in voids between the C 3 4- units. The compounds are electrically semiconducting. Ho 4 C 7 has a magnetic Curie-Weiss behaviour with θ= -28(4) K and µ eff = 8.8(2) µB.

Single crystals of the title compound have been prepared by the reaction of benzonitrile with LiN-(SiMe 3 ) 2 in hexane and subsequent evaporation of the solvent. Space group P2 1 /n, Z = 4, structure solution with 7945 observed unique reflections. R = 0.052. Lattice dimensions at -70 °C: a = 1485.2(9); b = 2486.9(11); c = 1568.9(8) pm; β = 91.06(4)°. The compound forms a trimeric ion ensemble in which two of the lithium cations are coordinated by three nitrogen atoms of two phenylamidinate an ions, the other one by four nitrogen atoms of two chelating phenylaminidate anions and in addition by the nitrogen atom of a benzonitrile molecule.

(MgBr 2· diglyme) 2 (1) crystallized in low yield from an ether solution of the Grignard compound mesMgBr (mes = mesityl) on adding diglyme. It is more conveniently prepared from an ether solution of MgBr 2 by addition of diglyme. The mixed solvate MgBr 2· diglyme thf (2) crystallized from a diglyme/tetrahydrofuran solution of 1 after addition of ether. An X-ray structure determination of 1 reveals dimeric units containing hexacoordinated Mg atoms surrounded by three oxygen atoms and three bromide atoms, with each kind of atoms arranged in a meridional fashion. The two octahedral MgO 3 Br 3 units share a common edge with two Br atoms. Compound 2 is a mononuclear complex with the Br atoms in cis-position. The diglyme ligand occupies meridional positions of a distorted MgBr 2 O 4 octahedron.