Reduction of aromatic ketones with the (dpp-BIAN)AlI(Et2O) complex

Reduction of benzophenone and 4,4′-bis(methoxy)benzophenone with the aluminum complex (dpp-BIAN)AlI(Et₂O) (1) containing the dianionic dpp-BIAN ligand (dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) affords the pinacolate complexes [(dpp-BIAN)AlI]₂[μ-O₂C₂Ph₄] (2) and [(dpp-BIAN)AlI]₂[μ-O₂C₂(C₆H₄OMe)₄] (3), respectively, which undergo the pinacolone rearrangement upon prolonged storage in diethyl ether to form [(dpp-BIAN)AlI]₂O (4). The reaction of 1 with fluoren-9-one produces stable pinacolate (dpp-BIAN)Al[μ-O₂(C₁₃H₈)₂] (7) and the (dpp-BIAN)AlI₂ complex (8). Compounds 2—4, 7, and 8 were characterized by ESR spectroscopy. Hydrolysis products of compounds 2 and 3 were characterized by ¹H NMR spectroscopy. The structures of complexes 4 and 7 were established by X-ray diffraction. dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1134–1140, July, 2006.     

Addition of nitriles to alkaline earth metal complexes of 1,2-bis[(phenyl)imino]acenaphthenes

Compounds [Sr(dpp-bian)(thf)4] (2), [Ba(dpp-bian)(dme)2.5] (3) and [Mg(dtb-bian)(thf)2] (4) (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene; dtb-bian = 1,2-bis[(2,5-di-tert-butylphenyl)imino]acenaphthene) were prepared by reduction of dpp-bian and dtb-bian with an excess of metallic Mg, Sr, or Ba in THF or DME. Reactions of [Mg(dpp-bian)(thf)3], 3, and 4 with diphenylacetonitrile gave keteniminates [Mg(dpp-bianH)(NCCPh2)(thf)2] (5), [Mg(dtb-bianH)(NCCPh2)(thf)2] (6), and [Ba(dpp-bianH)(NCCPh2)(dme)2] (7), respectively. The reaction of 2 with CH3C[triple chemical bond]N in THF gave [{Sr(dpp-bianH)[N(H)C(CH3)C(H)CN](thf)}2] (8). The compounds 2, 3, 5-8 were characterized by elemental analysis, and IR and NMR spectroscopy. Molecular structures of 2, 3, 7, and 8 were determined by single-crystal X-ray diffraction. In contrast to reactions of alkali-metal reagents, magnesium amides, or yttriumalkyls with alpha-H acidic nitriles, which are accompanied by an amine or an alkane elimination, the reactions of [Mg(dpp-bian)(thf)3] (1), 2, 3, and 4 with such nitriles proceeded with formation of Mg, Sr, and Ba keteniminates and simultaneous protonation of one nitrogen atom of the bian ligand. The NMR spectroscopic data obtained for complex 5 indicated that in solution the amino hydrogen atom underwent the fast (on the NMR timescale) shuttle transfer between both nitrogen atoms of the dpp-bianH ligand.     

Synthesis and structure of tetraphenylantimony hydrogen phthalate

Tetraphenylantimony hydrogen phthalate, Ph4SbOC(O)C6H4000H-o, was prepared by the reaction of pentaphenylantimony with phthalic acid. According to the data of X-ray structural analysis, the resulting compound is a trigonal-bipyramidal complex of antimony with three phenyl groups in equatorial positions; the fourth phenyl group and the carboxyl fragment are in axial positions. The CSbO angle is 177.5(1)° the Sb-C(Ph)_eq and Sb-C(Ph)ax distances are 2.099(4)-2.177(4) A and 2.129(4) A, respectively. The H atom of the free carboxyl group and the carbonyl O atom of another carboxylate group form an intramolecular hydrogen bond.DeceasedTranslated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2082–2085, August, 1996.     

Synthesis and Structure of 2-tert-Butylphenoxytetraphenylantimony

2-tert-Butylphenoxytetraphenylantimony Ph₄SbOC₆H₄(Bu-t)-2 was prepared by the reaction of pentaphenylantimony with 2-tert-butylphenol in toluene at 20°. The structure of the obtained compound was determined by X-ray diffraction. The Sb atom in this compound has a distorted trigonal-bipyramidal coordination with the aroxy group in the axial position. The Sb–C(Ph)_eqand Sb–C(Ph)_axdistances are 2.111(7)–2.138(7) and 2.180(7) Å the Sb–O and O–C_Ardistances are 2.143(4) and 1.363(8) Å, respectively. The C(Ph)_axSbO_Araxial angle is 174.1(2)°, while the SbOC angle is 126.7(4)°.     

Synthesis of magnesium catecholate and <Emphasis Type="Italic">o</Emphasis>-semiquinone complexes by oxidation of the metal with 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-<Emphasis Type="Italic">o</Emphasis>-benzoquinone

Oxidation of amalgamated magnesium metal with 3,6-di-tert-butyl-o-benzoquinone (1) in different aprotic organic solvents afforded magnesium catecholate and bis-o-semiquinolate complexes. The catecholate derivatives of magnesium CatMgL₂ (Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion, L = THF or Py) were synthesized in high yields in pyridine and tetrahydrofuran, respectively. The reactions in diethyl ether or dimethoxyethane produced hexacoordinated metal bis-o-semiquinolates SQ₂MgL_n (SQ is the 3,6-di-tert-butyl-o-benzoquinone radical anion, L = Et₂O, n = 2; L = DME, n = 1). The reaction with the use of toluene as the solvent gave a magnesium bis-o-semiquinolate complex containing the coordinated unreduced o-quinone molecule. The molecular structures of the [CatMgPy₂]₂ and SQ₂Mg·DME complexes were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–98, January, 2007.     

Quinone imines and aminophenols as precursors of new heterocycles

Cyclization of substituted quinone imines and diazabutadiene derivatives of aminophenols affords 4aH-phenoxazine or 4H-1,4-benzoxazine derivatives, which are finally transformed into the following fused heterocycles: the stable 1,4,6,8-tetra(tert-butyl)phenoxazin-10-yl radical and 7a,14a,15a, 15b-tetrahydro-14,16-dioxa-5,9-diaza-8,15-ethenohexaphene and 5a,6,11a, 12-tetrahydro[1,4]benzoxazino[3,2-b][1,4]benzoxazine derivatives. The influence of the substituents on the pathways of the reactions of intermediate benzoxazines and phenoxazines, such as oxidation, [2+4] dimerization, and the closure of the second ring, was studied. The structures of the fused heterocycles were determined by X-ray diffraction, NMR spectroscopy, and ESR. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2491–2496, November, 2005.     

Crystal structure of KAsUO<Subscript>6</Subscript>·<Subscript>3</Subscript>H<Subscript>2</Subscript>O at 100 and 293 K

The crystal structure of KAsUO₆·3H₂O was solved at 100 K and 293 K. KAsUO₆·3H₂O at T = 100 K: tetragonal, P4/ncc, a = 7.2037(6) Å, c = 17.811(2) Å; Z = 4, R1 = 0.0263, wR2 = 0.0546, for 618 independent reflections; at T = 293 K: tetragonal, P4/ncc, a = 7.1600(4) Å, c = 17.746(1) Å; Z = 4, R1 = 0.0263, wR2 = 0.0433 for 427 independent reflections. The results of X-ray analysis are compared with our previous data on heat capacity of this compound, and changes that take place in the structure at elevated temperature are considered.     

Synthesis and structure of 1,1′-bis(pentafluorophenyl)tetrahydrodigermane

Dehydrogenation of pentafluorophenylgermane in the presence of catalytic amounts of a Wilkinson complex, certain Rh^I ortho-benzosemiquinolate complexes, or (Ph₃P)₄Pt leads to tetrahydrodigermane, C₆F₅H₂GeGeH₂C₆F₅. X-ray analysis has confirmed thetrans-arrangement of the C₆F₅-cycles at the Ge atoms. The Ge-Ge bond length is 2.394(1) Å. The doublet pattern of the band due to the Ge-H bonds (v 2090 and 2104 cm^–1) in the IR spectrum is probably associated with nonequivalence of the hydrogen atoms in the molecule.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 315–318, February, 1994.