Beiträge zur Chemie des Phosphors. 223. Hexaisopropyl-icosaphosphan(6), P20i-Pr6 — Darstellung und kernresonanz-spektroskopische Strukturbestimmung von zwei Konstitutionsisomeren

Contributions to the Chemistry of Phosphorus. 223. Hexaisopropylicosaphosphane(6), P₂₀i? Pr₆ — Preparation and Structure Determination of Two Constitutional Isomers by Nuclear Magnetic Resonance Hexaisopropyl-icosaphosphane(6) has been obtained by reaction of i-PrPCl₂ with P₄ and magnesium and subsequent thermolysis of the crude reaction product. The compound is formed as a mixture of two constitutional isomers 1 and 2 of equal abundance, which have been almost purely isolated by HPLC as a mixture of the diastereomers 1 a , 1 b and in the form of the separate configurational isomers 2 a and 2 b , respectively. According to NMR-spectroscopic investigations, the new conjuncto-phosphane skeletons of 1 and 2 consist of a P₁₃(5)- and a P₉(5)-structural element analogous to that of brexane and of two P₁₁(5)-partial skeletons, respectively, joined in each case through a common P₂-bridge. Thus, 1 is 6,7,9,16,17,20-hexaisopropyloctacyclo[10.8.0.0^2,14.0^3,11.0^4,8.0^5,10.0^13,18.0^15,19]icosaphosphane and 2 is 7,9,15,17,19,20-hexaisopropyl-octacyclo[14.2.1.1^5,8.0^2,14.0^3,12.0^4,10.0^6,11.0^13,18]icosaphosphane. The phosphorus hydrogen compound P₂₀H₆ [22, 2c] should exhibit the same constitutional isomerism.     

Functionalization of Cubanes and Homocubanes via Oxidative Displacement of Iodine Using Hypervalent Iodine

The iodo group in 4-iodo-1-carbomethoxycubane (1) can be replaced by mesyloxy, tosyloxy and chloro by oxidative displacement with C₆H₅I(OH)OMs, C₆H₅I(OH)OTs and C₆H₅ICl₂, respectively. Similarly, the iodo group in the homocubyl compound 4-iodo-1-bromopentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]nonane-9-one ethylene acetal (2) was analogously replaced by mesyloxy, tosyloxy and chloro. Possible pathways for these reactions are discussed.     

A Safe,Simple and Rapid Synthesis of t-Butyl Chromate

Di-t-butyl chromate -(t-BuO)₂CrO₂, DTBC- has proven to be a potent and versatile oxidizing reagent, suitable for the direct introduction of a carbonyl group in an allylic position¹. The compound was prepared for the first time by Wienhaus² but Oppenauer³ introduced it as a new oxidizing reagent. DTBC is a crystalline compound with a melting point of 0°C^3,4 and is never used as such but always in a solution of a non polar solvent.     

A Porous Cadmium(II) Framework: Synthesis,Crystal Structure,Gas Adsorption,and Fluorescence Sensing Properties

The Cd^II compound, namely [Cd(Tppa)(SO₄)(H₂O)]_n ( 1 ) [Tppa = tris(4‐(pyridyl)phenyl) amine], was synthesized by the reaction of CdSO₄ · 8H₂O and Tppa under solvothermal conditions. Single crystal X‐ray diffraction analysis revealed that compound 1 features a 3D porous framework based on 1D inorganic –[Cd–SO₄–Cd]_n– chains. Topological analysis reveals that compound 1 represents a trinodal (3,4,6)‐connected topological network with the point symbol of {6.7²}₂{6⁴.7.10}{6⁴.7⁵.8⁴.10²}. Gas adsorption properties investigations indicate that compound 1 exhibits moderate adsorption capacities for light hydrocarbons at room temperature. Luminescencence property studies revealed that this Cd^II compound exhibits high fluorescence sensitivity for sensing of CS₂ molecule.     

N,N:N′,N′‐Bis(2,2'‐dihydroxy­biphen­yl‐3,3'‐dimethyl­idene)benzene‐1,2‐diamine dimeth­yl sulfoxide tetra­solvate

The title compound, 8,15,28,35‐tetra­aza­hepta­cyclo[35.3.1.1^2,6.1^17,21.1^22,26.0^9,14·0^29,34]tetraconta‐1(41),2,4,6(42),7,9,11,13,15,17,19,21(43),22,24,26(44),27,29,31,33,35,37,39‐docosaene‐41,42,43,44‐tetrol dimeth­yl sulfoxide tetra­solvate, C₄₀H₂₈N₄O₄·4C₂H₆OS, adopts a chair‐shaped C_2h symmetric conformation with crystallographically imposed inversion symmetry. Four intra­molecular hydrogen bonds are observed between phenol O and imine N atoms.     

Novel germylenes and stannylenes based on pyridine-containing dialcohol ligands

The reactions between M[N(SiMe₃)₂]₂ (M = Ge, Sn) and three pyridine-based dialcohols yielded germylenes and stannylenes 1-6. The composition and structures of the novel compounds were established by elemental analyses, ¹H and ¹³C NMR spectroscopy. The structures of insoluble species were confirmed by conversion to the corresponding dibromides 7-9. The single crystal structures of stannylene 4 and germylene 5 were determined by X-ray diffraction analyses. The germanium compound was found to be monomeric whilst the tin compound is a dimer. Both compounds possess strong transannular MN interaction in the solid phase.     

Formation of a silicon‐containing macrocycle with a pyridoxalimine Schiff base ligand

The reaction of dichlorodiphenylsilane with a polydentate Schiff base ligand derived from pyridoxal and 2‐hydroxyaniline yields the macrocyclic centrosymmetric silicon compound 9,27‐dimethyl‐3,3,21,21‐tetraphenyl‐2,4,20,22‐tetraoxa‐8,13,26,31‐tetraaza‐3,21‐disilapentacyclo[30.4.0.0^6,11.0^14,19.0^24,29]hexatrideca‐1(32),6,8,10,12,14,16,18,24,26,28,30,33,35‐tetradecaene‐10,28‐diol chloroform tetrasolvate, C₅₂H₄₄N₄O₆Si₂·4CHCl₃. The asymmetric unit contains half of the macrocycle and two molecules of chloroform, with C—H...O and C—H...N contacts binding the two guests to the host in the crystal structure. This macrocyclic silicon compound represents a promising host for molecular‐recognition processes and for the construction of nanostructures.     

The new binary intermetallic YbGe2.83

The new compound YbGe_2.83 was obtained from the reaction of Yb and Ge in liquid indium. The crystal structure of YbGe_2.83 adopts the trigonal, P3?m1 space group with a=b=8.3657(12) Å and c=7.0469(14) Å. The structure of YbGe_2.83 is a variant of the CaAl₂Si₂ structure type with ordered vacancies. Germanium atoms form double layers of puckered hexagons creating slabs that sandwich the Yb atoms. YbGe_2.83 can be classified as a Zintl compound with the formula Yb^(2+x)+(Ge_2.83)^(2+x)−. The deficiencies at the Ge sites cause a mixed/intermediate valent state of ytterbium (Yb^2.35+). Valence bond sum calculations suggest an average valence of Yb ions in YbGe_2.83 of 2.51 consistent with an intermediate valence compound.     

N-H…O,C-H… O hydrogen-bonded supramolecular frameworks in 4-fluoroanilinium and dicyclohexylaminium picrate salts

The asymmetric unit of compound (I), 4-fluoroanilinium picrate, C₆H₇NF⁺.C₆H₂N₃O₇^? contain one 4-fluoroanilinium cation and one picrate anion whereas in compound (II), dicyclohexylaminium picrate, C₁₂H₂₂N⁺.C₆H₂N₃O₇^? the asymmetric unit contains two sets of dicyclohexylaminium cation and picrate anion due to conformational difference between the molecules. In (I), all three nitro groups of the picrate anion are positionally disordered over two sites refined to major and minor components. The molecular ions of (I), interlinked through N–H???O and C–H???O hydrogen bonds forming two-dimensional supramolecular sheet along (-1 0 1) plane. Whereas in (II), the symmetry-independent molecules labeled as A and B molecule form independent one-dimensional supramolecular tape extending along (1 1 0) and (1 0 0) direction. The supramolecular tapes are interlinked through C–H???O interaction to form three-dimensional network in the crystalline solid in (II).

     

1,3‐Bridged p‐methyloctahomotetraoxacalix[4]arene–bis‐crown‐3

The title compound, 13,21,35,43‐tetra­methyl‐3,6,9,17,25,28,31,39,46,49‐decaoxahepta­cyclo­[21.21.3.3^11,33.0^2,41.0^10,15.0^19,24.0^32,37]pentaconta‐1,10,12,14,19,21,23,32,34,36,41,43‐dodecaene, C₄₄H₅₂O₁₀, differs from previously reported 1,3‐bridged calix­[4]­arene–bis‐crown compounds in having an enlarged calixarene ring and shorter polyoxy­ethyl­ene bridges. The cavity is partly filled by the bridges.     

Chemical Transformations of 4,6-Dimethyl-2β-hydroxy-8-oxo-3,5,7-trioxatetracyclo[7.2.1.04,11.06,10]dodecane

Reactions of 4,6-dimethyl-2β-hydroxy-8-oxo-3,5,7-trioxatetracyclo-[7.2.1.0.^4,11.0^6,10]dodecane 1 with nucleophiles have been studied. Reaction of 1 with alcohols, triethylsilane, allyltrimethylsilane, and methylthiotrimethylsilane in CH₂Cl₂ in the presence of TiCL₄, gave the substitution products 2,7a, 7b, and 7c in 80-90% yields. The substitution reaction took place chemoselectively on the hemiacetal group of I. Reaction of 1 with cyanotrimethylsilane in CH₂C1₂ in the presence of TiCL₄, gave compound 8 and the rearranged product 9. The structure of 9 was proven by X-ray analysis.     

Low‐Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Gramine (C11H14N2)

Low‐temperature heat capacities of gramine (C₁₁H₁₄N₂) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 401 K. A polynomial equation of heat capacities as a function of temperature was fitted by least squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at 5 K intervals. The constant‐volume energy of combustion of the compound at T=298.15 K was measured by a precision oxygen‐bomb combustion calorimeter as Δ_cU=−(35336.7±13.9) J·g⁻¹. The standard molar enthalpy of combustion of the compound was determined to be Δ_cH_m⁰=−(6163.2±2.4) kJ·mol⁻¹, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be Δ;_cH_m⁰=−(166.2±2.8) kJ·mol⁻¹ in accordance with Hess law.     

The [4 + 4] thermocyclization of 9‐anthraldehyde: synthesis,crystal structure,experimental and theoretical UV spectra,natural bonding orbital analysis and prediction of third‐order nonlinear optical properties

The dimer of 9‐anthraldehyde, namely heptacyclo[8.6.6.6^2,9.0^3,8.0^11,16.0^17,22.0^23,28]octacosa‐3,5,7,11,13,15,17(22),18,20,23(28),24,26‐dodecaene‐1,9‐carbaldehyde, C₃₀H₂₀O₂, has been synthesized by refluxing an ethanol solution in the presence of M(ClO₄)₂ and 1,3‐diaminopropan‐2‐ol (M = Co²⁺ or Cu²⁺). Its structure has been determined by single‐crystal X‐ray diffraction, showing it to be a new polymorph, referred to as polymorph II, in the monoclinic space group P2₁/n. It is compared with the previously reported triclinic modification [Ehrenberg (1968). Acta Cryst. B 24 , 1123–1125], which is referred to as polymorph I. The asymmetric unit of polymorph II contains two half molecules located on crystallographic centres, while the asymmetric unit of polymorph I includes one half molecule, also located on a crystallographic centre. Time‐dependent density functional theory (TD‐DFT) at the RB3LYP level using the 6‐31G(d,p) basis set was applied. The predicted electronic absorption spectrum is in good agreement with the experimental one. The analysis of the calculated electronic absorption spectrum of polymorph II was carried out in order to assign the observed electronic transitions and to determine their character. A natural bonding orbital (NBO) analysis was executed at the same level to evaluate charge‐transfer, intramolecular hydrogen‐bonding interactions and hyperconjugative interactions. The third‐order nonlinear optical (NLO) properties of the compound were appraised by the ZINDO/sum‐over‐states method in both static and dynamic states. The orientationally averaged (isotropic) value of γ for the compound is greater than the corresponding value of 4‐nitroaniline (pNA).     

Di- and trinuclear olato-bridged copper(II) compounds of 3,7-bis(3-olatopropyl)-1,3,5,7-tetraazabicyclo[3,3,1]nonane (protan); the structures of [{Cu(μ-protan)}2Cu](ClO4)2·H2O and [{Cu(μ-protan)}Cu(OH)2](ClO4)2·0.5(EtOH)

A compound with a linear trinuclear copper(II) cation, [Cu₃(μ-protan)₂](ClO₄)₂·H₂O (protanH₂ = 3,7-bis(3-hydroxypropyl)-1,3,5,7-tetraazabicyclo[3,3,1]-nonane) is formed by reaction of copper(II) perchlorate, 3-aminopropanol, ammonia and methanal. The cation is approximately centrosymmetrical with Cu?Cu = 2.9870(5) and 2.9485(5) Å. The terminal copper(II) ions are coordinated by nitrogen atoms 3 and 7 of the tetraazabicycle (Cu–N_mean = 2.021(5) Å) and the two oxygen atoms of the 3,7-bis(3-olatopropyl) substituents (Cu–O_mean = 1.911(3) Å), which also act as bridging groups to the central copper(II) ion (Cu–O_mean = 1.926(4) Å). The cation is both helically twisted (dihedral angle N3?N7?N3′?N7′ = 20(1)°) and bent (angle Cu?Cu?Cu = 171(1)°). The copper(II) ions have tetrahedrally twisted square planar primary coordination, with perchlorate ion oxygen atoms weakly coordinated axially to the two terminal copper(II) ions, on opposite sides of the “plane” of the molecule, while the central copper(II) ion is weakly coordinated axially by a water molecule, with all axial Cu–O distances ca. 2.9 Å. One N·CH₂·CH₂·CH₂·O chelate ring for each protan²⁻ ligand shows conformational disorder and the perchlorate ions show rotational disorder. Partial hydrolysis of the protan²⁻ compound gave a compound [{Cu(μ-protan)}Cu(OH)₂](ClO₄)₂·0.5(EtOH) which has a dinuclear cation, with one copper(II) ion in square-planar coordination by tetradentate protan²⁻ and the other in square-planar coordination by the two bridging oxygen atoms of the protan²⁻ ligand and by two hydroxide ions, with Cu?Cu = 3.045(1) Å. With differing mole ratios of the same reactants compounds of the dinuclear cation [{Cu(μ-pta)}₂]²⁺ (ptaH = 3(3-hydroxypropyl)-1,3,5,7-tetraazabicyclo[3,3,1]nonane) are formed.     

Cp Me5P6C5[M(CO)5]3: Ungewöhnliche reaktion des tricyclischen hexaphosphans Cp2P6 mit M(CO)5thf (M = Cr,W)

3,4-Bis[pentamethylcyclopentadienyl]tricyclo-[3.1.0.0^2,6] hexaphosphane 1 reacts with Cr(CO)₅thf or W(CO)₅thf to give the zwitterionic chromium complex 1,9,10-tris(pentacarbonylchromium)−3,4,5,6,11-pentamethyl-7-pentamethylcyclopentadienyl-3,4,5,6,11-pentacarba-penta-cyclo-[6.1. 1.^1,8.1^3,6.O^2,7.0^10,11 ]-4-en-7-ium-9-id-undeca-phosphane 2 and the analogous tungsten compound 3, respectively. The basic structures of 2 and 3 are similar to the cunean-moiety of the Hittorf-modification of phosphorus.     

Synthesis and reactions of [tris(trimethylsilyl)methyl]ethyl dichlorosilane

The crowded dichlorosilane TsiSiEtCl₂, (1), (Tsi = (Me₃Si)₃C) was prepared from the reaction between EtSiCl₃ and TsiLi, then it was reduced with LiAlH₄ to give TsiSiEtH₂, (2). The hydride (2) was then treated with two equivalents of ICl/CCl₄ or Br₂/CCl₄ to produce TsiSiEtI₂, (3), and TsiSiEtBr₂, (4), respectively. The reaction of compound (2) with one equivalent of ICl/CCl₄ gives TsiSiEtHI, (5). This product reacted with H₂O/dioxane in the presence of AgClO₄ or with dry MeOH to produce TsiSiEtHOH, (6), and TsiSiEtHOMe, (7), respectively. The compound (3) reacted with H₂O in DMSO/CH₃CN to give TsiSiEt(OH)₂, (8), and the compound TsiSiEtIOMe, (9), was prepared from the reaction of the compound (7) with ICl/CCl₄. When the dichloride (1) was treated with NaOMe/MeOH it gave (Me₃Si)₂CHSiEt(OMe)₂. It is suggested that the reaction proceeds through an elimination-addition mechanism. The dichloride (1) was also treated with KSCN, NaN₃ or NaOCN in CH₃CN to give S_N2 substitution products. All the new products were characterized by FTIR, ¹H NMR, and ¹³C NMR spectroscopy, mass spectrometry and elemental analysis.     

A chiral Mn(IV) complex and its supramolecular assembly: Synthesis, characterization and properties

The open air reaction of the chiral Schiff base ligand H₂L, prepared by the condensation of L-phenylalaninol and 5-bromosalicylaldehyde, with Mn^II(CH₃COO)₂.4H₂O yielded dark brown complex [Mn^IV L₂]·0·5 DMF (1). Compound 1 was characterized by elemental analysis, IR, UV-visible, CD and EPR spectroscopy, cyclic voltammetry and room temperature magnetic moment determination. Single-crystal X-ray analysis revealed that compound 1 crystallises in the monoclinicP2 ₁ space group with six mononuclear [Mn^IV L₂] units in the asymmetric unit along with three solvent DMF molecules. In the crystal structure, each Mn(IV) complex, acting as the building unit, undergoes supramolecular linking through C-H...0 bonds leading to an intricate hydrogen bonding network.     

A Mononuclear Uranium(IV) Single‐Molecule Magnet with an Azobenzene Radical Ligand

A tetravalent uranium compound with a radical azobenzene ligand, namely, [{(SiMe₂NPh)₃‐tacn}U^IV(η²‐N₂Ph₂^.)] ( 2 ), was obtained by one‐electron reduction of azobenzene by the trivalent uranium compound [U^III{(SiMe₂NPh)₃‐tacn}] ( 1 ). Compound 2 was characterized by single‐crystal X‐ray diffraction and ¹H NMR, IR, and UV/Vis/NIR spectroscopy. The magnetic properties of 2 and precursor 1 were studied by static magnetization and ac susceptibility measurements, which for the former revealed single‐molecule magnet behaviour for the first time in a mononuclear U^IV compound, whereas trivalent uranium compound 1 does not exhibit slow relaxation of the magnetization at low temperatures. A first approximation to the magnetic behaviour of these compounds was attempted by combining an effective electrostatic model with a phenomenological approach using the full single‐ion Hamiltonian.     

1,1,3,3-Tetrachlordisilazan

1,1,3,3-Tetrachlorodisilazane The new compound 1 can be prepared by the reaction of calciumoctamminedichloride, CaCl₂(NH₃)₈, with trichlorosilane, HSiCl₃. IR, Raman, ¹H and ²⁹Si NMR spectra show a planar Si₂NH framework, probably C₂-symmetry of the whole molecule and a symmetrical distribution of the four chlorine atoms. In 1 we have got a compound with Bronsted and Lewis acidity, which reacts with three equivalents of pyridine to HSiCl₂(py)₂? NH(py)? HSiCl₂. This addition compound exhibits a fourfold and a sixfold coordinated silicon atom as is shown by a ²⁹Si-solid-NMR spectrum. By thermal decomposition of 1 the new compound 1,3,5-trichloro-2,4,6-tris(dichlorosilyl)-cyclo-1,3,5-trisil-2,4,6-triazane, Si₆Cl₉H₆N₃, 4 , is formed. With piperidine, 1 reacts by substitution of all four chlorine atoms to compound 5 , whereas with diazomethane the NH-functionality is converted to a NCH₃ group in 6 . Attempts of lithiation lead mainly to a substitution of the chlorine atoms by alkyl groups     

Crystal Structure and Vibrational Spectrum of Thallium(I) Europium(II) Tetrathiophosphate(V), TIEu[PS4]

TlEu[PS₄] was synthesized from the elements in a sealed quartz ampoule at 1 150 K. The compound forms transparent orange needles, stable in air and moisture. It crystallizes in the orthorhombic system, space group Pnma (No. 62), with cell dimensions a = 12.157(2), b = 6.581(1), c = 8.802(2) Å, Z = 4. The crystal structure consists of discrete [PS₄]^3? anions interconnected by Tl⁺ and Eu²⁺. The tetrahedral [PS₄]^3? groups are slightly distorted with P? S bond lengths in the range 2.028 to 2.043 Å. These tetrahedral anions are arranged in such a way that the sulfur atoms form columns of distorted trigonal S₆ prisms along [0 0 1]. The columns are condensed via common edges to puckered layers parallel to (1 0 0). The interlayer region consists of empty distorted half-cubes and tetrahedral holes, half of them filled by P atoms. The trigonal prisms in the columns are centered alternately by Tl⁺ and Eu²⁺. In this way, the structure can be regarded as an ordered superstructure of the InNi₂ type, where half of the tetrahedral holes are filled by phosphorus atoms: InInNi₄□ ? TlEuS₄P□. TlEu[PS₄] is a centrosymmetric variant of the TlSn[PS₄] structure type (space group Pna2₁). The vibrational spectrum is in accordance with the X-ray crystal structure, the Raman and infrared vibrations are assigned on the basis of [PS₄]^3? units with C_2v symmetry.