Reaction of ethylene with the unsaturated cluster complex H2Os3 (CO)10

Treatment of H₂Os₃(CO)₁₀ with excess ethylene forms ethane and a hydridovinyl cluster complex HOs₃(CO)₁₀(CHCH₂), which rearranges in refluxing octane to the vinylidene complex H₂Os₃(CO)₉(CCH₂).     

Cleavage of the sulfur-sulfur bond in 2,4-dinitrophenyl 4-substituted phenyl disulfides by trans-[IrX(CO)(PPh3)2]

A series of 2,4-dinitrophenyl 4-Y-phenyl disulfides (Y=NO₂, Br, F, H, CH₃, or CH₃O) have been shown to react with trans-IrX(CO)(PPh₃)₂ (X=Cl, Br, or I) in refluxing benzene to form “oxidative-elimination” products of the type, [IrX(SC₆h₄Y)(SC₆H₃(NO₂)₂)(CO)(PPh₃)]₂. The physical properties of these complexes are discussed in relation to their structure in the solid state and in solution. In particular, available infrared spectral data indicate that these complexes contain 2,4-dinitrobenzenethiolato bridging groups and that the substituted arenethiolato ligand is trans to carbon monoxide.     

Thermal decomposition of the biguanide complexes of the 3d-transition metals

The thermal decomposition (TG, DTG and DTA) of the complexes of biguanide with the following metals was studied: V, Cr, Mn, Co, Ni, Cu and Zn. Structural water, when present, is first eliminated at ～100–150°C; this is followed by a main decomposition state at ～300–350°C. Pyrolytic residues are analysed and characterised by their x-ray powder diffraction patterns and are found to be the oxides V₂O₅, Cr₂O₃, Mn₃O₄, Co₃O₄, NiO, CuO and ZnO, respectively. The decomposition curves of the free ligand (biguanide) and biguanide sulphate are also given. The decomposition characteristics are discussed.     

Complexes of silver(III) with oxoanions

Silver(III) has a half-life at pH 11 of several hundred seconds in aqueous solutions in the presence of 0.1–1.0 M concentrations of certain basic oxoanions (Oxo) (phosphate, carbonate, borate, pyrophosphate, and arsenate). This compares with a lifetime of a few seconds at pH 11 in the absence of these oxoanions. UV-visible spectra and kinetic data for these solutions are interpreted as evidence for the following equilibria in the pH range 9–13.Ag(OH)₄^?1 + H₂O ? Ag(OH)₃H₂O + OH^? (1)Ag(OH)₄^?1 + Oxo ? Ag(OH)₃Oxo + OH^? (2)Ag(OH)₃Oxo + H₂O ? Ag(OH)₂(Oxo)H₂O + OH^? (3) Values of K₃ lie in the range 10^?3 < K₃ <10⁴ M for the systems studied. K₂ is estimated to be ～10² for phosphate and slightly smaller for the other systems. Ag(OH)₄^? undergoes an unusual reaction with pyrophosphate at pH ～ 8 to form a novel silver(II) complex, [Ag(P₂O₇)₂]^6?, for which EPR and electronic absorption spectral parameters are reported.     

Azole chemistry : XI. 3-Dimethylsila-2H-imidazo[1,2-a]benzimidazoles

2-Aminobenzimidazole, and its 5,6-dichloro, 5,6-dimethyl, and 5,6-dinitro derivatives react with bromomethyldimethylchlorosilane in anhydrous tetrahydrofuran at room temperature to give the new heterocycles, 3-dimethylsila-2H-imidazo [1,2-a]benzimidazoles, in good yields. The spectral properties of these heterocycles are discussed.     

A synthesis of (±)-cryptojaponol and (±)-taxodione

A new method for the synthesis of highly substituted catechols involving the decarboxylation of an α,β-epoxyenone was developed and employed in a synthesis of two diterpenes, cryptojaponol and taxodione.     

Base induced rearrangements of α-halosulfones α-sulfonyl carbanions with bridgehead electrofugal centre

The KOtBu-induced Ramberg-Bäcklund reaction of the trans bicyclic halosulfones 1 and 2 is studied in DME and DMSO. Strong indications are obtained that the reaction proceeds via the intermediate Z-episulfone with retention-inversion (involving exo-S-geometry).¹ Base induced epimerization at the nucleofugal centre (from axial to equatorial halogen) is demonstrated in DMSO.     

Carbonyl complexes of molybdenum and tungsten with sulfur donors: V. Reactions of carbonyl complexes of molybdenum(0) with uninegative (X,Y)-donor ligands (X,Y = S,N, O)

The reactions of the zerovalent carbonyl complexes Mo(CO)₆ and Mo(CO)₄(bipy) with a series of uninegative bidentate (X,Y)-donor ligands (X,Y = xanthates, dithiocarbamates, o-aminophenoxide, o-aminothiophenoxide, 2-picolinate and thioacetate) lead to new anionic tetracarbonyl complex anions [Mo⁰(X,Y)(CO)₄]^?. These anions, which can be isolated as their tetraphenylphosphonium salts, contain the (X,Y)-ligand as a bidentate group. In the case of (X,Y) = monothioacetate the decarbonylated species [PPh₄][Mo^II(TA)₃] is formed. The reacions of the new complexes with allyl bromide and methyl iodide are described.     

Chlorination of α-sulfonyl carbanions with hexachloroethane: A novel preparation of α-halosulfones

The cyclic sulfones1,2, and3 are lithiated in benzene with n-butyllithium. Lithiation is demonstrated to lead to α-mono, α,α′-di and/or α,α-di and α,α,α′ trimetallation. The lithiated sulfones are chlorinated with hexachloroethane (HCE). Some mechanistic aspects of the reaction of the lithiosulfones with vicinal dihalides are discussed.     

Synthesis of compounds with juvenile hormone activity—XVII : A stereoselective synthesis of dl-C17-Cecropia juvenile hormone

A stereoselective synthesis of the title compound (2) was accomplished using a coupling reaction of a C₆-unit (4) with a C₁₀-unit (8) as the key-step.     

Thermal and photochemical reactions of allylcobaloximes with para-substituted benzenesulphonyl chloride under aerobic and anaerobic conditions

The compounds p-XC₆H₄SO₂Cl (X = Cl, Br, I, OMe) react regiospecifically with allyl-, 2-methylallyl-, 3-methylallyl- and 3,3-dimethylallyl-cobaloximes under thermal and photochernical conditions. A rearranged organic product is obtained in each case. The yields are much better in photochemical reactions. A chain mechanism is involved in which the organosulphonyl radical and cobaloxime(II) are the chain propagating species. Yields of the sulphones are drastically reduced when the reactions are carried out in the presence of oxygen.     

Syntheses and characterization of new palladium(II) complexes with functionally substituted cyclopentadienyl groups

Thallium [1-(p-tolylimino)-2-methylpropyl]cyclopentadienide, Tl[C₅H₄C(=NC₆H₄CH₃)CH(CH₃)₂], was prepared and treatment of the salt with [{PdCl₂(PREt₂)}₂] (R = Ph and Et) yielded mononuclear palladium(II) complexes, [Pd{η⁵-C₅H₄C(=NC₆H₄CH₃)CH(CH₃)₂}Cl(PREt₂)], with an imidoyl-substituted η⁵-cyclopentadienyl group. In addition, [Pd(η⁵-C₅H₄-COY)Cl(PPhEt₂)] (Y = CH₃ and OCH₃) complexes were obtained from the sodium salts of their substituted cyclopentadienyl groups. These new compounds were characterized by means of ¹H and ¹³C NMR and IR spectroscopy.     

Catalytic hydrogenation of propene over polymer supported rhodium complexes

Hydrogenation of propene and other substrates has been studied in flow and batch reactors using various rhodium catalysts. The results show that in some cases rhodium metal is probably formed, but only if solvent is present. A possible explanation is given.     

Structural changes resulting from doping Ti2O3 with Sc2O3 or Al2O3

The crystal structures of (Ti_1?xSc_x)₂O₃, x = 0.0038, 0.0109, and 0.0413, and of (Ti_0.99Al_0.01)₂O₃, have been determined from X-ray diffraction data collected from single crystals using an automated diffractometer, and have been refined to weighted residuals of 25–34. Cell constants have also been determined for x = 0.0005, 0.0019, and 0.0232. The compounds are rhombohedral, space group $\text{R}\text{3}\text{c}$, and are isomorphous with α-Al₂O₃. The hexagonal cell dimensions range from a = 5.1573(2)Å, c = 13.613(1)Å for (Ti_0.9995Sc_0.0005)₂O₃ to a = 5.1659(4)Å, c = 13.644(1)Å for (Ti_0.9587Sc_0.0413)₂O₃, and a = 5.1526(2)Å, c = 13.609(1)Å for (Ti_0.99Al_0.01)₂O₃. Sc and Al substitution cause similar increases in the short near-neighbor metal-metal distance across the shared octahedral face; for Sc doping the increase is from 2.578(1) Å in pure Ti₂O₃ to 2.597(1) Å in (Ti_0.9587Sc_0.0413)₂O₃. By contrast, changes in the metal-metal distance across the shared octahedral edge appear to be governed by ionic size effects. The distance increases from 2.994(1) Å in Ti₂O₃ to 3.000(1) Å in (Ti_0.9587Sc_0.0413)₂O₃ and decreases to 2.991(1) Å in (Ti_0.99Al_0.01)₂O₃.     

Configurational inversion and hexachloroethane chlorination of α-sulfonylcarbanions

The cis fused bicyclic sulfones 1a, 1c and 3a are lithiated in benzene with n-butyllithium under concomitant cis/trans isomerization of the ring fusion, involving intramolecular proton transfer. H/D exchange of the three α-hydrogens in protic solvents proceeds with retention of configuration. The lithiated sulfones are chlorinated with hexachloroethane (HCE) and show a strong preference for introduction of halogen at an equatorial α-position.     

The reactions of hydrosilanes with trifluoropropene and pentafluorostyrene catalyzed by ruthenium, rhodium and palladium complexes

The reactions of hydrosilanes with trifluoropropene (TFP) and pentafluorostyrene (PFS) catalyzed by Ru₃(CO)₁₂ or RhCl(PPh₃)₃ give β-R_f-vinylsilane (1) and/or β-R_f-ethylsilane (2) (R_f = perfluorocarbon group). The 1/2 ratio is highly dependent on the nature of hydrosilane used. The ruthenium catalyst favors the formation of 1 compared with the rhodium catalyst. Neither -R_f-vinylsilane nor -R_f-ethyl-silane was formed at all. Possible mechanisms which can accommodate characteristic features of these reactions are discussed. The hydrosilylation of TFP with dichloro-methylsilane catalyzed by PdCl₂(PhCN)₂/2PPh₃ gives the -adduct (9a) exclusively, and this is transformed to the corresponding dialkoxysilanes, silane diol, oligosilane diols and cyclic oligosiloxanes.