Temporary phase segregation processes during the oxidation of (Fe0.7Mn0.3)0.99O in N2---H2O atmosphere

A two-step thermochemical cycle with the ternary metal oxide system (Fe_{1 − x}Mn_x)₃O₄/(Fe_{1 − x}Mn_x)_{1 − y}O is applied to convert solar energy to chemical energy. Experimental investigations on the water splitting reaction of (Fe_{1 − x}Mn_x)_{1 − y}O revealed temporary formation of a manganese rich rock salt phase and an iron rich spinel phase due to phase segregation processes.     

Cyclization of nitriles 41. Reaction of arylmethylenemalononitriles with malononitrile; crystal structure of 1-amino-3.5-diphenyl-2,4,4,6,6-pentacyano-1-Cyclohexene

1-Amino-3,5-diaryl-2,4,4,6,6-pentacyano-1-cyclohexenes are prepared by reaction of arylmethylenemalononitriles with malononitrile. The cyclohexene ring of (IVa) has a distorted N₂-C¹=C²-C⁷=N¹ fragment. Steric effects in (IVa) cause a substantial increase in C⁶-C¹ and C³-C⁴ bond length to 1.546(4) and 1.570(4) Å, respectively.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2771–2775, December, 1989.     

Synthesis and the molecular and crystal structure of 1, 4-dihydro-1-methyl-4-(2, 3, 3-tricyanoallylidene)quinoline

The reaction of 1, 4-dimethylquinolinium iodide with tetracyanoethylene in presence of triethylamine proceeds highly regioselectively with the formation of l, 4-dihydro-l-methyl-4-(2, 3, 3-tricyanoallylidene)quinoline. It was shown by an x-ray structural investigation that its crystal is built from two, not quite planar, symmetrically independent molecules (IIIa) and (IIIb): The dihedral angles in these between the dihydroquinoline nucleus and the tricyanoallylidene group are 8.6 and 10.8. An examination is made of the influence on the structure of the molecules of steric factors and effects of the conjugation of the donor and acceptor parts of the molecules, leading to considerable intramolecular transfer of charge. In the crystal the molecules form stacks of the type ...aabb... with the participation of both symmetrically independent molecules and with interplanar distances d of 3.341, 3.449, and 3.347 å, which may be conducive to intermolecular transfer of charge.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 690–696, March, 1991.     

Stereoselective 1,3-dipolar cycloaddition of unsaturated nitriles to isoquinolinium ylids. Molecular and crystal structure of 1,2-trans-3,3-dicyano-1-carbamoyl-2-(3-pyridyl)-1,2,3,4-tetrahydrobenzo[f]indolizine

The reactions of isoquinolinium ylids with arylmethylenemalononitriles proceed highly stereoselectively via a pathway involving synchronous 1,3-dipolar cycloaddition to give 1,2-trans-2-aryl-3,3-dicyano-1-carbamoyl(benzoyl)-1,2,3,4-tetrahydrobenzo[f]indolizines. The regiospecificity and stereospecificity of these reactions were confirmed by the results of PMR spectroscopy and x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1248–1254, September, 1991.     

Antiferromagnetic complexes with a metal—metal bond: VIII. Synthesis and structure of the antiferromagnetic heteronuclear cluster, “butterfly” (or “metal-chain”), (Cp4Cr2Ni2)(μ3-S)2(μ4-S)

By heating the mixture of solutions of (CpCrSCMe₃)₂S (I) in benzene and [CpNi(CO)]₂ in pentane followed by chromatography on alumina, dark cherry-red needles of the heteronuclear cluster (Cp₄Cr₂Ni₂)(μ³-S)₂(μ⁴-S) (II) were obtained, whose structure was established on the basis of a complete X-ray analysis. The crystals are rhombic, spatial group Pbca; a = 12.07(1), b = 18.50(2), c = 17.36(1) Å, Z = 8. The metallic skeleton of II has the “butterfly” or “metal-chain” structure with a direct CrCr bond (2.62(1) Å) and inequivalent CrNi bonds, 2.86(1) and 2.64(1) Å, while the Ni·Ni distance is nonbonding (4.34(1) Å). The NiCr₂ triangle planes produce a dihedral angle of 127°. The two μ³-bridged sulfur atoms locate under these triangles whereas the third sulfur atom is μ⁴-bridging coordinating all four metal atoms in the cluster with mean NiS and CrS distances of 2.29(1) and 2.25(1) Å, respectively. The Ni₂S₃ group is planar and almost perpendicular to the CrCr axis. Complex II is anti-ferromagnetic and its exchange parameter — 2J (418 cm^-1) is close to that found for the initial binuclear complex I (— 2J = 430 cm^-1 with a CrCr bond length of 2.689(8) Å). The role of the Ni coordination number in the generation of II is discussed.     

Synthesis and x-ray study of triferrocenyliodidephosphonium triiodide

A series of iodine derivatives of ferrocenylphosphorus compounds has been obtained. An X-ray investigation of [Fc₃PI]⁺I₃^? has been carried out. All ferrocenyl fragments posses close geometric parameters, similar to those of ferrocene and its derivatives. The positive charge of the cation is localized on the phosphorus atom. Symmetrical I₃^? anions of linear configuration form zigzag-shaped chains, as is usual for triiodides. The cation—anion interaction is realized through short I…I contacts.     

Crystal structure of organosilicon compounds LII. 1-carboxy-1,1,2,2,3,3,4,4-octaphenyltetrasilane and 4,4,5,5,6,6,7,7,8,8-decaphenyl-4,5,6,7,8-pentasilaundeca-1,10-diene

For Communication LI, see [1].