Magnetic Properties of FeBO3 in the Low-Spin State

JETP Letters - Changes in the magnetic properties of FeBO3 single crystals in the course of spin crossover occurring with increasing pressure up to 63 GPa are studied both experimentally and...     

Hetrocyclic Thiones and Their Analogs in Reactions of 1,3-Dipolar Addition: VI. Reactions of Thiazoline-2-thione with Nitrile Imines

Reactions of thiazoline-2-thione with C,N-disubstituted nitrile imines were investigated. The reaction products are substituted 2-(1,3,4-thiadiazol-2-ylideneamino)ethanethiols and bis[2-(1,3,4-thiadiazol-2-ylideneamino)ethyl] disulfides. The reaction of thiazoline-2-thione with a double excess of nitrile imine did not considerably change the process route. The structure of compounds obtained was proved by X-ray diffraction analysis. A presumable scheme is given describing the formation of compounds obtained.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 776–782.Original Russian Text Copyright © 2005 by Firsova, Dolgushina, Polukeev, Ioannisyan, Zavodnik, Stash, Bel’skii, Galishev.     

Synthesis of pyrroloisoquinolines from papaverine

papaverine and its derivatives react with p-chlorophenacyl bromide to give the corresponding quaternary salts, which are converted into pyrrolo[2,1-a]isoquinolines by the action of bases.     

Regioselectivity of the methanolysis of polychlorinated biphenyls

Regioselectivity of the methanolysis of lower polychlorinated biphenyls with sodium methoxide in a mixture of methanol and DMSO at 100–130°С was studied. It was found that 2,4,4'-tricholobiphenyl is much more reactive than 2,4-dichlorobiphenyl. This results in different mechanisms of substitution. 2,4-Dichlorobiphenyl reacts with sodium methoxide by the elimination–addition mechanism to form four monosubstitution products in comparable quantities. 2,4,4'-Trichlorobiphenyl reacts with the methodixe ion by the classical SNAr mechanism, with preferential substitution of the 2-chlorine atom.     

Reactions of iridium bis(phosphinite) pincer complexes with protic acids

Iridium pincer complexes [C₆H₃-2,6-(OPBu^t ₂)₂]Ir(H)Cl (10) and [4-EtOOCC₆H₂-2,6-(OPBu^t ₂)₂]Ir(H)Cl (11) react with protic acids undergoing metallation of one of the tert-butyl groups to form double cyclometallated products [4-R-C₆H₂-2-(OPBu^t ₂)-6-(OP(Bu^t)CMe₂CH₂)]IrCl (12, R = H; 13, R = COOEt), which are stable in air. Complex 12 reacts with CO and Bu^tNC giving the corresponding 18-electron complexes [C₆H₃-2-(OP-Bu^t ₂)-6-(OP(Bu^t)CMe₂CH₂)]Ir(L)Cl (14, L = CO; 15, L = CNBu^t). The structure of compound 14 was established by X-ray diffraction analysis.     

Coupling of Bis(xylylisocyanide) Palladium(II) Complex with 1,2,4-Thiadiazole-5-amines

The coupling of bis(xylylisocyanide) complex of Pd(II) with 1,2,4-thiadiazole-5-amines leads to the formation of an equilibrium mixture of the binuclear complexes. In each of the studied cases, one of the formed complexes is the kinetic product, and the other one is the thermodynamic product. The complexes which are thermodynamic products have been isolated in the pure form and characterized by means of high-resolution mass spectrometry, IR and NMR spectroscopy, and X-ray diffraction analysis. NMR study of the regioisomerization in a solution has revealed that the relative stability of the thermodynamic products in comparison with the kinetic ones is higher than for the corresponding regioisomers containing 1,3-thiazole or 1,3,4- thiadiazole fragment.     

Synthesis,Structure, and Catalytic Activity of Cyclometalated Iridium Complexes with a Bidentate POC Ligand

Synthesis, characterization and catalytic activity of cyclometalated iridium complexes with a bidentate POC ligand is presented. Metalation of POC-H (di-tert-butyl(phenoxy)phosphane) with [Ir(COD)Cl]₂ proceeded rapidly at room temperature and afforded mixture of (POC)(POC-H)IrHCl ( 1 a ) and (POC)(COD)IrHCl ( 1 b ), from which complexes (POC)(L)IrHCl where L=PPh₃ ( 1 c ), bipyridine ( 1 d ) and [2,2′-bipyridine]-6,6′-diol ( 1 e ) were prepared through ligand exchange. The compounds were tested in acceptorless dehydrogenation of 1-phenylethanol and transfer dehydrogenation of ethanol in a context of comparison with pincer counterparts (POCOP)IrHCl and (PCN)IrHCl. An attempt to prepare a dihydride complex from 1 e led to dimeric complex [(POC)(bipy-diol−)IrH]₂ ( 3 ) that could explain the low activity of 1 e . DFT studies provided insight into POC-H vs POCOP-H metalation mechanism.     

Synthesis and Wittig Reaction of Formylated (Trifluoromethylfuryl)methanephosphonates

Methods of synthesis of 4-functionalyzed (5-trifluoromethylfur-2-yl)methanephosphonates and (5-methyl-2-trifluoromethylfur-3-yl)methanephosphonate are developed. Their formylation with ethyl formate in the presence of sodium foil is studied. Spectral characteristics of tautomers of obtained derivatives of phosphonoacetic aldehyde are evaluated. It is shown that interaction of obtained formyl derivatives with ethoxycarbonylmethylenetriphenylphosphorane regardless of the structure of the furan fragment leads to 4-furylsubstituted alkyl 4-(diethoxyphosphoryl)but-3-enoate, the abnormal product of Wittig reaction.     

Adamantylation of nitro-substituted aromatic amines in protic acids

Adamantylation of mono-and dinitro-substituted aromatic amines in sulfuric and phosphoric acids and in a mixture of phosphoric and acetic acids gives mainly the corresponding N-adamantyl derivatives. The results of kinetic measurements showed reversible character of the process.     

Alkylation of nitrogen heterocycles with 1,3-bis(hydroxymethyl)ferrocene. Generation of the ferrocene dicarbocation [{1,3-(CH2)2C5H3}Fe(C5H5)]2+

The alkylation of imidazole and 5-benzyloxycarbonyl-3,4-diethylpyrrole with 1,3-bis-(hydroxymethyl)ferrocene (1) afforded bis-imidazole (4) and bis-pyrrole (7) derivatives of ferrocene, respectively. The reaction of diol 1 with trifluoroacetic acid gave the dicarbocationic complex [{1,3-(CH₂)₂C₅H₃}Fe(C₅H₅)]²⁺ (2) characterized by ¹H NMR spectroscopy.