Andrés Ibañez

Synthesis, reactivity and molecular structure of phosphino tetramethyl cyclopentadienyl complex (η5: η1-C5Me4CH2PPh2)Re(CO)2

The fulvene complex (eta(6)-C(5)Me(4)CH(2))Re(C(6)F(5))(CO)(2) reacts at the exocyclic methylene carbon with potassium diphenylphosphide to yield the anionic species [(eta(5)-C(5)Me(4)CH(2)PPh(2))Re(C(6)F(5))(CO)(2)](-) (). Protonation of with HCl at 0 degrees C produces the hydride complex trans-(eta(5)-C(5)Me(4)CH(2)PPh(2))Re(C(6)F(5))(H)(CO)(2) (). Thermolysis of a hexanes solution of , under nitrogen atmosphere, produces the chelated complex (eta(5):eta(1)-C(5)Me(4)CH(2)PPh(2))Re(CO)(2) () in good yield. The thermolysis under a CO atmosphere affords a mixture of the complexes (eta(5):eta(1)-C(5)Me(4)CH(2)PPh(2))Re(CO)(2) () and (eta(5)-C(5)Me(4)CH(2)PPh(2))Re(CO)(3) (). The reaction of with two electron donor ligands yields (eta(5)-C(5)Me(4)CH(2)PPh(2))Re(CO)(2)(L) (, L = CO; , L = PMe(3); , L = (t)BuNC). Complex also reacts with I(2), HBF(4) and MeOTf to yield the cationic compounds trans-[(eta(5):eta(1)-C(5)Me(4)CH(2)PPh(2))Re(R)(CO)(2)](+) (, R = I; , R = H; , R = Me). Upon treatment with chloroform, the hydride complex converts to the corresponding chloro derivative . The trans stereochemistry for complexes have been assigned on basis of nu(CO) IR intensities and (13)C-NMR chemical shifts. The reaction of the cationic complexes (, ) with KI and Me(3)NO.2H(2)O yields the neutral species cis-(eta(5):eta(1)-C(5)Me(4)CH(2)PPh(2))Re(I)(R)(CO) (, R = I, , R = Me). The molecular structure of and have been determined by X-ray crystallography.

Five bicyclo[3.3.0]octa-2,6-dienes

A series of five compounds containing the bicyclo[3.3.0]octa-2,6-diene skeleton are described, namely tetramethyl cis,cis-3,7-dihydroxybicyclo[3.3.0]octa-2,6-diene-2,4-exo,6,8-exo-tetracarboxylate, C(16)H(18)O(10), (I), tetramethyl cis,cis-3,7-dihydroxy-1,5-dimethylbicyclo[3.3.0]octa-2,6-diene-2,4-exo,6,8-exo-tetracarboxylate, C(18)H(22)O(10), (II), tetramethyl cis,cis-3,7-dimethoxybicyclo[3.3.0]octa-2,6-diene-2,4-exo,6,8-exo-tetracarboxylate, C(18)H(22)O(10), (III), tetramethyl cis,cis-3,7-dimethoxy-1,5-dimethylbicyclo[3.3.0]octa-2,6-diene-2,4-exo,6,8-exo-tetracarboxylate, C(20)H(26)O(10), (IV), and tetramethyl cis,cis-3,7-diacetoxybicyclo[3.3.0]octa-2,6-diene-2,4-exo,6,8-exo-tetracarboxylate, C(20)H(22)O(12), (V). The bicyclic core is substituted in all cases at positions 2, 4, 6 and 8 with methoxycarbonyl groups and additionally at positions 3 and 7 with hydroxy [in (I) and (II)], methoxy [in (III) and (IV)] or acetoxy [in (V)] groups. The conformations of the methoxycarbonyl groups at positions 2 and 4 are exo for all five compounds. Each C(5) ring of the bicyclic skeleton is almost planar, but the rings are not coplanar, with dihedral angles of 54.93 (7), 69.85 (5), 64.07 (4), 80.74 (5) and 66.91 (7) degrees for (I)-(V), respectively, and the bicyclooctadiene system adopts a butterfly-like conformation. Strong intramolecular hydrogen bonds exist between the -OH and C=O groups in (I) and (II), with O...O distances of 2.660 (2) and 2.672 (2) A in (I), and 2.653 (2) and 2.635 (2) A in (II). The molecular packing is stabilized by weaker C-H...O(=C) interactions, leading to dimers in (I)-(III) and to a chain structure in (V). The structure series presented in this article shows how the geometry of the cycloocta-2,6-diene skeleton changes upon substitution in different positions and, consequently, how the packing is modified, although the intermolecular interactions are basically the same across the series.

Organonickel(II) complexes with anionic tridentate 1, 3-bis(azolylmethyl)phenyl ligands. synthesis, structural characterization and catalytic behavior

A reacao de 2-bromo-1, 3-bis(bromometil)benzeno com 3, 5-dimetilpirazol e 1H-indazol produz os ligantes tridentados 2-bromo-1, 3-bis(3, 5-dimetilpirazol-1-ilmetil)benzeno (1) e 2-bromo-1, 3-bis(indazol-2-ilmetil)benzeno (2). Estes compostos reagem com [Ni(cod)2] em tetraidrofurano (thf) para formar os complexos de adicao oxidativa [NiBr{1, 3-bis(azolilmetil)fenil-N, C, N}], azol = 3, 5-dimetilpirazol (3) e indazol (4), os quais foram isolados em bons rendimentos como solidos amarelos estaveis e caracterizados por meio de analise elementar, espectroscopia de absorcao no infravermelho com transformada de Fourier (FTIR), espectrometria de massa e ressonância magnetica nuclear (NMR). Adicionalmente, as estruturas moleculares de 2 e 4 foram determinadas por difratometria de raios X de monocristal. O complexo 4 foi testado como catalisador na reacao de polimerizacao de etileno

8,8-Diethyl-1,4,5,8-tetra-hydro-naphthalene-1,4,5-trione

The title molecule, C14H14O3, contains two fused six-membered carbon rings with keto groups at positions 1, 4 and 5 and a gem-diethyl group at position 8. The molecule is close to planar (maximum deviation = 0.044 Å), with one ethyl group at each side of the molecular plane, with exception of the keto group at position 1 which is slightly deviated from the plane and disordered over two positions one on each side of it (occupancies 0.80/0.20). The packing of the molecule shows weak bonded chains along a through C—H⋯O contacts and two intramolecular C—H⋯O interactions are also present.

Disodium zinc bis-(sulfate) tetra-hydrate (zinc astrakanite) revisited.

We present a new low-temperature refinement of disodium zinc bis(sulfate) tetrahydrate {systematic name: poly[tetra-μ-aqua-di-μ-sulfato-zinc(II)disodium(I)]}, [Na2Zn(SO4)2(H2O)4]n or Zn astrakanite, which is an upgrade of previously reported data [Bukin & Nozik (1974 ▶). Zh. Strukt. Khim. 15, 712–716]. The compound is part of an isostructural family containing the Mg (the original astrakanite mineral), Co and Ni species. The very regular ZnO(aqua)4O(sulfate)2 octahedra lie on centres of symmetry, while the rather distorted NaO(aqua)2O(sulfate)4 octahedra appear at general positions, linked into a three-dimensional network by the bridging water molecules and the fully coordinated sulfate groups.

(E)-3-(2,3-Dimethoxyphenyl)-1-(2-hydroxy-4-methoxyphenyl)prop-2-en-1-one

The molecular conformation of the title compound, C18H18O5, is stabilized by a strong intramolecular hydrogen bond between the hydroxyl and carbonyl groups. The C=C double bond displays an E configuration while the carbonyl group shows an S-cis configuration relative to the double bond. The dihedral angle between the two rings is 15.0 (1)°.

Tetra­aqua(3,4,7,8-tetra­methyl-1,10-phenanthroline-κ2N,N′)­zinc(II) thio­sulfate

In the title complex of zinc(II) with 3,4,7,8-tetramethyl-1,10-phenanthroline (tmph), viz. [Zn(C 16 H 16 N 2 )(H 2 O) 4 ](S 2 O 3 ), the metal atom has a monomeric octahedral ZnN 2 O 4 complex environment comprising two N-atom donors from the tmph group and four aqua O-atom donors. The complex cation is connected to four thiosulfate anions through a compact hydrogen-bonding network involving all coordinated aqua H-atom donors and all the outer acceptors (O and S) of the anion.

Bis(acetato-κ2O,O′)(4,4′-dimethyl-2,2′-bipyridine-κ2N,N′)­zinc

The molecular structure of the title compound, [Zn(CH3COO)2(C12H12N2)], consists of isolated molecules bisected by a twofold rotation axis which goes through the ZnII cation and halves the organic base through the central C—C bond. The ZnII ion is coordinated by two N atoms from one molecule of the aromatic base and four O atoms from two bidentate, symmetry-related acetate anions, which coordinate asymmetrically [Zn—O distances of 2.058 (2) and 2.362 (3) Å], while the two Zn—N bond distances are equal as imposed by symmetry [2.079 (2) Å]. The crystal structure is supported by a number of weak C—H⋯O interactions and C—H⋯π contacts, with no π–π interactions present, mainly hindered by the substituent methyl groups and the relative molecular orientation. The result is a three-dimensional structure in which each molecule is linked to eight different neighbors.

(Acetyl­acetonato)dibromido[2,2-diphenyl­hydrazin-1-ido(1−)][2,2-diphenyl­hydrazin-1-ido(2−)]molybdenum(VI)

In the title compound, [MoBr2(C12H11N2)(C12H10N2)(C5H7O2)], the MoVI atom is six-coordinated in a distorted octahedral geometry by two N atoms from the diphenylhydrazide(1−) and diphenylhydrazide(2−) ligands, two O atoms from a bidentate acetylacetonate ligand and two Br− ions. The molecules form an inversion dimer via a pair of weak C—H⋯O hydrogen bonds and a π–π stacking interaction with a centroid–centroid distance of 3.7401 (12) Å. Weak intramolecular C—H⋯Br interactions and an intramolecular π–π stacking interaction with a centroid–centroid distance of 3.8118 (15) Å are also observed.

9,10-Dihydr­oxy-4,4-dimethyl-5,8-dihydro­anthracen-1(4H)-one

In the title molecule, C16H16O3, the ring system is planar and an intramolecular hydrogen bond is present. The molecular packing is dominated by an intermolecular hydrogen bond and by π-stacking interactions [interplanar separation 3.8012 Å].