Reactivity of 2-halo-2H-azirines. Part 3: Dehalogenation of 2-halo-2H-azirine-2-carboxylates

The dehalogenation of 2-halo-3-phenyl-2H-azirine-2-carboxylates is described. Using sodium borohydride and tributyltin hydride 3-phenyl-2H-azirine-2-carboxylates were obtained in moderate yields. The synthesis of a new 2-bromo-2H-azirines with a chiral auxiliary, 10-phenylsulfonylisobornyl 2-bromo-3-phenyl-2H-azirine-2-carboxylate, is reported. Its dehalogenation led to 10-phenylsulfonylisobornyl 2H-azirine-2-carboxylate as single stereoisomer together with the formation of 10-phenylsulfonylisobornyl acetate.     

Structural chemistry of Ba2CdS3, Ba2CdSe3, BaCdS2, BaCu2S2 and BaCu2Se2

The structures of all compounds were determined from three dimensional single crystal X-ray diffraction data and refined by least squares. Ba₂CdS₃ and Ba₂CdSe₃ are isostructural, Pnma, a = 8.9145(6)Å, b = 4.3356(2)Å, c = 17.2439(9)Å for the former compound and a = 9.2247Å, b = 4,4823(6)Å, c = 17.8706(11)Å for the latter, z = 4, R = 0.0751 and R = 0.0462, respectively. The compounds are isostructural with the previously reported Mn analogues and with K₂AgI₃. Cd ions are in tetrahedral environment and the tetrahedra form infinite linear chains by corner sharing. Ba ions are in 7-fold coordination in which 6 anions form a trigonal prism and 1 anion caps one of the rectangular faces. BaCdS₂, Pnma, a = 7.2781(3)Å, b = 4.1670(1)Å, c = 13.9189(6)Å, z = 4, R = 0.0685. Cd ions can be considered to have a triangular planar coordination with CdS distances of 2.47 and 2.53 Å (twice). Two additional S ions are at 2.89 and 3.22 Å to complete a triangular bipyramidal configuration. Ba is in 7-fold coordination with the anions forming a trigonal prism which is capped on one rectangular face. The compound is isostructural with BaCdO₂ and is related to the structure of BaMnS₂. BaCdSe₂ could not be prepared. BaCu₂S₂ and BaCu₂Se₂ are isostructural, Pnma, a = 9.3081(4)Å, b = 4.0612(3)Å, c = 10.4084(5)Å for the sulfide and a = 9.5944(6)Å, b = 4.2142(4)Å, c = 10.7748(8)Å for the selenide, z = 4, R = 0.0634 and 0.0373, respectively. Ba ions are in the usual 7-fold, capped hexagonal prism, coordination. However, 9 Cu ions also can be considered to form a trigonal prism with all rectangular faces capped, around Ba since the BaCu distances range from 3.24 to 3.54 Å for the sulfide and from 3.37 to 3.67 Å for the selenide. One of the Cu ions is in a very distorted tetrahedral environment and the second one is located in a more regular tetrahedral configuration of the anions. Two independent infinite chains of tetrahedra are present. They are formed by sharing of two adjacent edges of each tetrahedron and then these chains in turn are linked by corner sharing into a three-dimensional network of tetrahedra.     

Die Struktur von Cp2TiMe2

The structure of dimethyltitanocene, Cp₂TiMe₂, has been determined: monoclinic, space group P2₁/n, lattice constants (at −100°C) a = 6.818(2), b = 11.571(2), c = 13.387(3) Å, β = 92.36(2)°, and Z = 4. It is isostructural with Cp₂ZrMe ₂ and Cp₂HfMe₂. The Ti-C(σ) bond lengths are 2.170(2) and 2.181(2) Å and the C(σ)-Ti-C(σ) angle is 91.3(1 )°.     

Natural radiative lifetimes in the2 S 1/2 and2 D 3/2, 5/2 sequences of neutral copper

Natural radiative lifetimes have been measured of the 3d ¹⁰ ns ² S _1/2 (n=6?10) and of the 3d ¹⁰ nd ² D _{3/2, 5/2} (n=5?9) sequences by using two step excitation of copper atoms in an atomic beam. The states investigated were populated by the light from two pulsed dye lasers pumped by the same Nd:YAG laser. The lifetimes of the² D sequence increase regularly with increasing principal quantum number. This is not the case for the² S series, because of configuration interaction in the² P series. In addition the lifetime of the 3d ¹⁰5p ² P _3/2 state has been measured together with its branching ratio.     

Syntheses on the basis of 2H-chromen-2-one and 2H-chromene-2-thione

4-Hydroxy-2H-chromen-2-one and 4-hydroxy-2H-chromene-2-thione reacted with allyl bromide, 1,1,3-trichloroprop-1-ene, and 1,3-dichlorobut-2-ene to give the corresponding ethers, which were oxidized to (2-oxo-2H-chromen-4-yloxy)acetic acid with potassium permanganate, and various derivatives of that acid were obtained. 3-(3,3-Dichloroprop-2-enyl)-7-hydroxy-4-methyl-2H-chromen-2-one and 3-(3,3-dichloroprop-2-enyl)-7-hydroxy-4-methyl-2H-chromene-2-thione were synthesized, and some their transformations were studied.     

A dinuclear hydride complex of platinum(I) containing both bidentate and monodentate bis(diphenylphosphino)methane ligands: the crystal structure of [Pt2H(Ph2PCH2PPh2)(μ-Ph2PCH2PPh2)2][PF6]

The crystal structure of the title compound has been determined from 6049 X-ray diffractometric intensities with I > 3σ(I), and refined by a least-squares procedure to R = 0.050. The crystals are monoclinic, space group P2₁/n, a = 13.702(2) b = 14.255(2), c = 39.556(6) Å, β = 94.75(1)°, Z = 4. The structure of the cation displays two different coordination modes of the Ph₂PCH₂PPh₂ ligands. Two of these are bidentate, bridging the Pt-Pt bond [2.769(1)Å] to form a Pt₂(μ-Ph₂PCH₂PPh₂)₂ nucleus, while the third acts as a monodentate two-electron donor. The hydrido ligand was not located, but its position is inferred from the coordination geometry of the platinum atom to which it is bonded. The metalligand distances are: Pt-P(trans to P) 2.248(3)–2.289(4) and Pt—P(trans to Pt) 2.347(4) Å.     

Crystal structure of trans*-[PtEnPyNO2(OH,NO2)*]Cl·2H2O

The structure of trans*-[PtEnPyNO₂(OH,NO₂)*]Cl·2H₂O was determined by X-ray crystallography. The crystals are monoclinic, a = 31.185(6)Å, b = 12.198(2)Å, c = 8.432(2)Å, b = 100.8(2)°, Z = 8, space group C2/c, R = 0.031 for 2059 reflections with I > 2σ(I). In the complex cation, the polyhedron of the Pt atom is an octahedron formed by five nitrogen atoms from ethylenediamine (Pt-N(aver.), 2.062(7) Å), pyridine (Pt-N, 2.053(7) Å), two NO₂ groups (Pt-N, 2.064(7) Å), and the oxygen atom of the OH group in trans position to the nitro group (Pt-O, 1.999(7) Å). Complex cations, anions Cl^?, and crystal water molecules are linked together through a branched system of hydrogen bonds.     

Magnetism and phase relations of the PrAl2CaAl2, GdAl2CaAl2 systems

The magnetic properties and phase relations of the ternary systems Pr_1?xCa_xAl₂ and Gd_1?xCa_xAl₂ are reported. The first system exhibits complete miscibility whereas the second shows a miscibility gap extending from x = 0.5 to 0.8. The ternaries were examined magnetically to ascertain whether antiferromagnetism could be produced by replacing the trivalent rare earth ion with divalent Ca. Results for the (Pr, Ca)Al₂ system give some indication that the exchange changes sign when 80% or more of the Pr is replaced by Ca. The α-phase (Gd-rich) alloys in the (Gd,Ca)Al₂ system are ferromagnetic with Curie temperatures only modestly reduced from that of GdAl₂. The β-phase (Ca-rich) alloys in this system are paramagnetic to 4.2°K. The evidence suggests that PrAl₂ and CaAl₂ are electronically similar in regard to band structure and both differ in band structure from GdAl₂.     

Tartrate der TypenLn 2(H2 T)3·xH2O undLnH5 T 2·xH2O einiger Seltenerdmetalle

The following compounds were isolated and more closely studied by means of thermal analysis, X-ray scattering and IR absorption spectra and determination of solubilities: Pr₂(H₂ T)₃ · 6 H₂O, Nd₂(H₂ T)₃ · 6 H₂O, Sm₂(H₂ T)₃ · 5 H₂O, Gd₂(H₂ T)₃ · 5 H₂O, Tb₂(H₂ T)₃ · 5 H₂O, Dy₂(H₂ T)₃ · 5 H₂O, Ho₂(H₂ T)₃ · 5 H₂O, Er₂(H₂ T)₃ · 5 H₂O, PrH₅ T ₂ · 2 H₂O, NdH₅ T ₂ · 2 H₂O, SmH₅ T ₂ · 2 H₂O, GdH₅ T ₂ · 3 H₂O, TbH₅ T ₂ · 3 H₂O, DyH₅ T ₂ · 3 H₂O, HoH₅ T ₂ · 3 H₂O, ErH₅ T ₂ · 3 H₂O.     

Alkyl- und aryl-komplexe des iridiums und rhodiums: X. Chelatphosphin-stabilisierte rhodiumorganyle Rh(R)[PhP(CH2CH2CH2PPh2)2]: synthese,NMR-spektroskopischer cis,trans-einfluss und molekülstruktur von Rh(2-MeC6H4)[PhP(CH2CH2CH2PPh2)2]

The organorhodium(I) complexes Rh(R)[PhP(CH₂CH₂CH₂PPh₂)₂] (R  CH₂CMe₃, CH₂SiMe₃; 2-MeC₆H₄, 4-MeC₆H₄, 2,4-Me₂C₆H₃, 2,4,6-Me₃C₆H₂; C₂Ph) have been prepared and characterized by ³¹P and ¹H NMR spectroscopy and an X-ray structure determination of the tolyl derivative Rh(2-MeC₆H₄)-[PhP(CH₂CH₂CH₂PPh₂)₂].For these compounds, the relative ³¹P coordination shifts Δ(PPh₂) > Δ(PPh) distinctly reflect the electron-releasing properties of the organoligands σ-bonded trans to PPh. As expected, coupling between the ¹⁰³Rh nucleus and phenylphosphino P atoms is weak and varies only little as the strong trans influence groups R are changed. In contrast to this insensitivity of ¹J(Rh-PPh) to R, Rh-P coupling within the Ph₂P-Rh-PPh₂ moieties shows considerable dependence upon the nature of the C-donor producing the cis influence series sp³-C <sp²-C < sp-C.The ortho-tolyl complex crystallizes from toluene as 1/1 solvate Rh(2-MeC₆H₄)[PhP(CH₂CH₂CH₂PPh₂)₂] · C₇H₈. Crystals are orthorhombic, space group Pbc2₁, with a 1017.9(7), b 1974.3(14), c 2177.6(11) pm, and Z = 4. The structure has been refined to R = 0.079 for 2249 unique data with F₀ > 3σ(F₀). Metal-phosphorus distances are 225.7(5) and 229.6(6) pm for Rh-PPh₂ and 227.3(6) pm for Rh-PPh.     

Iminofuran chemistry: VII. Intramolecular cyclization of 2-N-aryl-substituted derivatives of 2-amino-4-aryl-4-oxobut-2-enoic and 2-amino-5,5-dimethyl4-oxohex-2-enoic acids

The cyclization at the treatment of acetic anhydride of 4-aryl-2-arylamino-4-oxobut-2-enoic and 2-arylamino-5,5-dimethyl-4-oxohex-2-enoic acids was investigated furnishing derivatives of 5-aryl-3-aryl-imino-3H-furan-2-ones and 4-arylamino-2-tert-butyl-2,5-dihydro-5-oxofuran-2-yl acetate respectively. 2-N²-Methylenesubstituted 4-aryl-2-hydrazino-4-oxobut-2-enoic and 5,5-dimethyl-2-hydrazino-4-oxohex-2-enoic acids cleanly underwent cyclization under the effect of acetic anhydride into 5-aryl-3-hydrazono-3H-furan-2-ones and 5-tert-butyl-3-hydrazono-3H-furan-2-ones.     

Base dependent purported synthesis of congested 2-aminobenzylamines and tetrahydro-2-oxoquinazolines from 2-pyranones

An expeditious and concise synthesis of highly congested 2-amino-3-aminomethyl-5-methylsulfanyl/-sec-aminobiphenyl-4-carbonitrile 4 and 1-tert-butoxycarbonyl-6-sec-amino-8-aryl-5-cyano-2-oxo-1,2,3,4-tetrahydroquinazoline 5 has been delineated through base catalyzed ring transformation of 6-aryl-4-methylsulfanyl/-sec-amino-2H-pyran-2-one-3-carbonitrile 1 with 1,3-bis(tert-butoxycarbonylamino)-2-propanone 2, followed by TFA catalyzed hydrolysis of the intermediate [3-tert-butoxycarbonylaminomethyl-4-cyano-5-methylsulfanyl/-sec-aminobiphenyl-2-yl]carbamic acid tert-butyl ester 3 in moderate yield. The mechanism of formation of 5 has been established through isolation and transformation of the intermediate 3 to the 1-tert-butoxycarbonyl-6-sec-amino-8-aryl-5-cyano-2-oxo-1,2,3,4-tetrahydroquinazoline.     

Crystal structure of calcium dihydroethylenediaminetetraacetate(2-) dihydrate Ca(H2Edta)·2H2O

The crystals of Ca(H₂Edta)·2H₂O (orthorhombic system, a = 8.5919(7) Å, b = 17.807(2) Å, c = 18.941(2) Å; Z = 8, space group Pbca) precipitate from solutions of Na₂H₂Edta·2H₂O and CaCl₂. The Ca atom is surrounded by the oxygen atoms of the water molecule and the carboxyl groups of the five neighboring H₂Edta^2? anions with protonated nitrogen atoms (distorted octahedron). As a result, a three-dimensional framework of [Ca(H₂O)H₂Edta)] with built-in crystal water molecules is formed.     

Synthesis of 2′-deoxy-5-fluoro-5′-O-1″,3″,2″-oxazaphosphacyclohexa-2″-yluridine 2″-oxide and related compounds

2′,3′-O-Isopropylidene-5′-O-1″,3″,2″-oxazaphosphacyclohex-2″-yl-uridine 2″-oxide has been obtained by the action of phosphoryl chloride and N-methylmorpholine, followed by 3-aminopropan-1-ol, on 2',3'-O-isopropy-lidineuridine. A similar reaction carried out on 3'-O-acetylthymidine, followed by removal of the acetyl group gave 5′-O-1″,3″,2″-oxazaphospha-2″-yl-thymidine 2″-oxide. Both of these compounds were obtained more conveniently by treatment of 2',3'-O-isopropylideneuridine and thymidine respectively with 2-chloro-1,3,2-oxazaphosphacyclo-hexane 2-oxide in pyridine. Similar treatment of 2′-deoxy-5-fluorouridine gave 2′-deoxy-5-fluoro-5′-O-1″,3″,2″-oxazaphosphacyclohex-2″-yluridine 2″-oxide. The latter compound was tested for activity against S 180 Crocker sarcoma and L 1210 mouse leukaemia. Only a marginal activity against the S 180 sarcoma was detected. However inactivity of the compound in inducing leukopenia indicated that it might be of low toxicity and that further testing of the compound would be justified.     

Hyperfine structure constants of the CaII states 4s 2 S 1/2 and 4p 2 P 1/2, 3/2 and the nuclear quadrupole moment of43Ca

The hyperfine structure splittings of the 4s ² S _1/2 → 4p ² P _{1/2, 3/2} transitions in⁴³CaII have been measured by fast ion beam collinear laser spectroscopy. The resonant laser interaction was observed using non-optical detection based on optical ground state depopulation pumping, state selective neutralization and charge state separated particle counting. The extracted magnetic dipole hyperfine structure constants for⁴³CaA(² S _1/2)=?805(2) MHz,A(² P _1/2)=?145.5(1.0) MHz andA(² P _3/2)=?31.9(0.2) MHz are in excellent agreement with relativistic many body perturbation theory predictions available for this alkali-like ion. The combined results are used to evaluate the semi-empirical analysis method. From the electrical quadrupole hyperfine structure constantB(² P _3/2)=?6.7(1.4) MHz and the calculatedB/Q value for this one valence electron configuration, the nuclear quadrupole momentQ(⁴³Ca)=?0.043(9)b is derived. This result supports a previous evaluation based on the hyperfine structure of the two valence electron³ P configurations of CaI.     

Magnesium and cadmium containing Heusler phases REPd2Mg,REPd2Cd,REAg2Mg,REAu2Mg and REAu2Cd

Twenty-eight new Heusler phases REPd₂Mg, REPd₂Cd, REAg₂Mg, REAu₂Mg and REAu₂Cd with different rare earth elements were synthesized from the elements in sealed niobium ampoules in a water-cooled sample chamber of an induction furnace. The samples were characterized by powder X-ray diffraction. The cell volumes show the expected lanthanide contraction. The structures of YPd₂Cd, GdPd₂Cd, GdAu₂Cd, Y_1.12Ag₂Mg_0.88 and GdAg₂Mg were refined based on single crystal diffractometer data. The magnetic properties were determined for fifteen phase pure samples. LuAu₂Mg is a weak Pauli paramagnet with a susceptibility of 1.0(2) × 10⁻⁵ emu mol⁻¹ at room temperature. The remaining samples show stable trivalent rare earth ions and most of them order magnetically at low temperatures. The ferromagnet GdAg₂Mg shows the highest ordering temperature of T_C = 98.3 K. ¹¹³Cd and ⁸⁹Y MAS NMR spectra of YAu₂Cd and YPd₂Cd confirm the presence of unique crystallographic sites. The resonances are characterized by large Knight shifts, whose magnitude can be correlated with electronegativity trends.     

Proton conductivity in TaH(PO4)2 · 2H2O + SiO2 composite electrolytes

The composite electrolytes of composition (1 ? x)TaH(PO₄)₂ · 2H₂O/xSiO₂ (x = 0.2–0.4) are synthesized, and their transport properties are characterized over a wide temperature range. Doping with highly dispersed silica only insignificantly changes the proton conductivity of tantalum hydrogenphosphate below 370 K; above 820 K, the conductivity increases. The evolution of the phase composition of TaH(PO₄)₂ · 2H₂O and its base materials during thermolysis is studied.     

Derivatographic studies on transition metal complexes. XII. Thermal isomerization of trans-[CrBr2en2]Br·H2O and cis-[CrBr2tn2]Br·2 H2O in the solid phase

The thermal trans-to-cis isomerization of trans-[CrBr₂en₂]Br·H₂O and cis-to-trans isomerization of cis-[CrBr₂tn₂]Br·2 H₂O were studied by means of derivatographic and isothermal measurements. In both cases isomerization took place in anhydrous state after the complete dehydration. The activation energies for dehydration of the above two complexes were evaluated isothermally to be 61 and 38 kJ mole^?1, respectively, and for their isomerization to be 420 and 275 kJ mole^?1, respectively. These data were compared with those for the corresponding chloro complexes and the ease of isomerization between them was discussed.     

Synthesis and crystal structures of the dioxovanadium complexes [VO2L1] and [VO2L2]2

Two new oxovanadium complexes, [VO₂L¹] (I) and [VO₂L²]₂ (II), where L¹ and L² are the deprotonated forms of 4-bromo-2-[(2-diethylaminoethylimino)methyl]phenol (HL¹) and 4-bromo-2-{[2-(2-hydroxyethylamino)ethylimino]methyl}phenol (HL²), respectively, have been synthesized and characterized by IR spectra and single crystal X-ray diffraction. The crystal of I is monoclinic: space group P2₁/n, a = 14.300(3), b = 7.010(2), c = 15.460(2) ?, ?? = 107.401(2)°, V = 1478.7(5) ?³, Z = 4. The crystal of II is monoclinic: space group P2₁/c, a = 7.270(2), b = 15.373(3), c = 11.893(3) ?, ?? = 99.302(2)°, V = 1311.8(5) ?³, Z = 2. Complex I is a mononuclear dioxovanadium(IV) complex. Complex II is a centrosymmetric dinuclear dioxovanadium(V) complex with a V...V distance of 3.117(2) ?. The Vatom in I is in a distorted square-pyramidal coordination, and that in II is in an octahedral coordination. The difference in the structures of the complexes is largely induced by the hydrogen bonds during the self-assembly process.     

Palladium-catalyzed synthesis of 2-allylindole and 2-allylbenzofuran derivatives from 2-((trimethylsilyl)ethynyl)arenes

A new protocol for the synthesis of 2-allylindole and 2-allylbenzofuran derivatives has been developed from readily accessible starting material, 2-((trimethylsilyl)ethynyl)arenes via Pd-catalysis. The presence of trimethylsilyl group in the alkyne is vital for this reaction. Stereoselectivity of 2-allylindole derivatives is controlled by the use of different nitrogen-protecting groups for 2-((trimethylsilyl)ethynyl)aniline. The CO₂Me protection gives Z-isomers, whereas acetyl protection gives E-isomers.