Two new [Ni(tren)2]2+ complexes: [Ni(tren)2]Cl2 and [Ni(tren)2]WS4

Both title compounds, bis­[tris(2‐amino­ethyl)­amine]­nickel(II) dichloride, [Ni(tren)₂]Cl₂, (I), and bis­[tris(2‐amino­ethyl)­amine]­nickel(II) tetra­thio­tungstate, [Ni(tren)₂]WS₄, (II), contain the [Ni(tren)₂]²⁺ cation [tren is tris(2‐amino­ethyl)­amine, C₆H₁₈N₄]. The tren mol­ecule acts as a tridentate ligand around the central Ni atom, with the remaining primary amine group not bound to the central atom. In (I), Ni²⁺ is located on a centre of inversion surrounded by one crystallographically independent tren mol­ecule. In the [Ni(tren)₂]²⁺ cation of (II), the Ni atom is bound to two crystallographically independent tren mol­ecules. The Ni atoms in the [Ni(tren)₂]²⁺ complexes are in a distorted octahedral environment consisting of six N atoms from the chelating tren mol­ecules. The counter‐ions are chloride anions in (I) and the tetrahedral [WS₄]^2? anion in (II). Hydro­gen bonding is observed in both compounds.     

Metallocene‐mediated cationic ring‐opening polymerization of 2‐methyl‐ and 2‐phenyl‐oxazoline

The cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline and 2‐phenyl‐2‐oxazoline was efficiently used using bis(η⁵‐cyclopentadienyl)dimethyl zirconium, Cp₂ZrMe₂, or bis(η⁵‐tert‐butyl‐cyclopentadienyl)dimethyl hafnium in combination with either tris(pentafluorophenyl)borate or tetrakis(pentafluorophenyl)borate dimethylanilinum salt as initiation systems. The evolution of polymer yield, molecular weight, and molecular weight distribution with time was examined. In addition, the influence of the initiation system and the monomer on the control of the polymerization was studied. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 000: 000–000, 2011     

Cationic Zinc Hydride Catalyzed Carbon Dioxide Reduction to Formate: Deciphering Elementary Reactions,Isolation of Intermediates,and Computational Investigations

Zinc has been an element of choice for carbon dioxide reduction in recent years. Zinc compounds have been showcased as catalysts for carbon dioxide hydrosilylation and hydroboration. The extent of carbon dioxide reduction can depend on various factors, including electrophilicity at the zinc center and the denticity of the ancillary ligands. In a few cases, the addition of Lewis acids to zinc hydride catalysts markedly influences carbon dioxide reduction. These factors have been investigated by exploring elementary reactions of carbon dioxide hydrosilylation and hydroboration by using cationic zinc hydrides bearing tetradentate tris[2-(dimethylamino)ethyl]amine and tridentate N,N,N′,N′′,N′′-pentamethyldiethylenetriamine in the presence of triphenylborane and tris(pentafluorophenyl)borane.     

2,5‐Dimethyl‐6,7‐dihydrobenzo[h]pyrazolo[1,5‐a]quinazoline and 2‐tert‐butyl‐5‐methyl‐6,7‐dihydrobenzo[h]pyrazolo[1,5‐a]quinazoline

In both 2,5‐dimethyl‐6,7‐dihydrobenzo[h]pyrazolo[1,5‐a]quinazoline, C₁₆H₁₅N₃, (I), and 2‐tert‐butyl‐5‐methyl‐6,7‐dihydrobenzo[h]pyrazolo[1,5‐a]quinazoline, C₁₉H₂₁N₃, (II), which crystallizes with Z′ = 2 in the space group P, the non‐aromatic carbocyclic rings adopt screw‐boat conformations. The molecules of (I) are linked into chains of rings by a combination of C—H...N and C—H...π(arene) hydrogen bonds, while in (II) there are no hydrogen bonds of any kind.     

Double complexes [Co(NH3)5(H2O)]2[Zr3F18]·6H2O and [Co(NH3)6]2[Zr3F18]·6H2O

The structures of orthorhombic bis[pentaammineaquacobalt(III)] tetra‐μ₂‐fluorido‐tetradecafluoridotrizirconium(IV) hexahydrate (space group Ibam), [Co(NH₃)₅(H₂O)]₂[Zr₃F₁₈]·6H₂O, (I), and bis[hexaamminecobalt(III)] tetra‐μ₂‐fluorido‐tetradecafluoridotrizirconium(IV) hexahydrate (space group Pnna), [Co(NH₃)₆]₂[Zr₃F₁₈]·6H₂O, (II), consist of complex [Co(NH₃)_x(H₂O)_y]³⁺ cations with either m [in (I)] or and 2 [in (II)] symmetry, [Zr₃F₁₈]⁶⁻ anionic chains located on sites with 222 [in (I)] or 2 [in (II)] symmetry, and water molecules.     

Metallocene-mediated cationic polymerization of vinyl ethers: Kinetics of polymerization and synthesis and characterization of statistical copolymers

The cationic polymerization of ethyl, n-butyl and iso-butyl vinyl ether, EVE, BVE and iBVE, respectively, was efficiently conducted using bis(η⁵-cyclopentadienyl)dimethyl hafnium, Cp₂HfMe₂, or bis(η⁵-cyclopentadienyl)dimethyl zirconium, Cp₂ZrMe₂ in combination with either tris(pentafluorophenyl)borate, B(C₆F₅)₃, or tetrakis(pentafluorophenyl)borate dimethylanilinum salt, [B(C₆F₅)₄]^?[Me₂NHPh]⁺, as initiation systems. The evolution of polymer yield, molecular weight and molecular weight distribution with time was examined. In addition, the influence of the initiating system, the monomer and the reaction conditions on the control of the polymerization was studied. Furthermore, statistical copolymers of EVE with BVE were prepared employing Cp₂HfMe₂ and [B(C₆F₅)₄]^?[Me₂NHPh]⁺ as the initiation system. The reactivity ratios were estimated using both linear graphical and non-linear methods. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions and the mean sequence length, which were derived using the monomer reactivity ratios. The glass transition temperatures, Tg, of the copolymers were measured by Differential Scanning Calorimetry, DSC, and the results were compared with predictions based on several theoretical models. The kinetics of thermal decomposition of the copolymers along with the respective homopolymers was studied by thermogravimetric analysis within the framework of the Ozawa-Flynn-Wall and Kissinger methodologies.     

Double-salt formation in crystal structures containing [Co(en)3]Cl3

The structures of three racemic double salts of [Co(en)₃]Cl₃ (en is ethane-1,2-diamine, C₂H₈N₂), namely, bis[tris(ethane-1,2-diamine-κ²N,N′)cobalt(III)] hexaaquasodium(I) heptachloride, [Co(en)₃]₂[Na(H₂O)₆]Cl₇, bis[tris(ethane-1,2-diamine-κ²N,N′)cobalt(III)] hexaaquapotassium(I) heptachloride, [Co(en)₃]₂[K(H₂O)₆]Cl₇, and ammonium bis[tris(ethane-1,2-diamine-κ²N,N′)cobalt(III)] heptachloride hexahydrate, (NH₄)[Co(en)₃]₂Cl₇·6H₂O, have been determined, and the structural similarities with the parent compound, tris(ethane-1,2-diamine-κ²N,N′)cobalt(III) trichloride tetrahydrate, [Co(en)₃]Cl₃·4H₂O, are highlighted. All four compounds crystallize in the trigonal space group Pc1. When compared with the parent compound, the double salts show a modest increase in the unit-cell volume. The structure of the chiral derivative [Λ-Co(en)₃]₂[Na(H₂O)₆]Cl₇ has also been redetermined at cryogenic temperatures (120 K) and the disorder noted in a previous report has been accounted for.     

Aluminium(III) amidinates formed from reactions of `AlCl' with lithium amidinates

The disproportionation of AlCl(THF)_n (THF is tetrahydrofuran) in the presence of lithium amidinate species gives aluminium(III) amidinate complexes with partial or full chloride substitution. Three aluminium amidinate complexes formed during the reaction between aluminium monochloride and lithium amidinates are presented. The homoleptic complex tris(N,N′‐diisopropylbenzimidamido)aluminium(III), [Al(C₁₃H₁₉N₂)₃] or Al{PhC[N(i‐Pr)]₂}₃, (I), crystallizes from the same solution as the heteroleptic complex chloridobis(N,N′‐diisopropylbenzimidamido)aluminium(III), [Al(C₁₃H₁₉N₂)₂Cl] or Al{PhC[N(i‐Pr)]₂}₂Cl, (II). Both have two crystallographically independent molecules per asymmetric unit (Z′ = 2) and (I) shows disorder in four of its N(i‐Pr) groups. Changing the ligand substituent to the bulkier cyclohexyl allows the isolation of the partial THF solvate chloridobis(N,N′‐dicyclohexylbenzimidamido)aluminium(III) tetrahydrofuran 0.675‐solvate, [Al(C₁₉H₂₇N₂)₂Cl]·0.675C₄H₈O or Al[PhC(NCy)₂]₂Cl·0.675THF, (III). Despite having a twofold rotation axis running through its Al and Cl atoms, (III) has a similar molecular structure to that of (II).     

Poly[tris(diorganophosphinato)alanes]

Poly[tris(diorganophosphinato)alanes], [Al(OPRR′O)₃]_n, were synthesized in which the organic moieties (R,R′) contained from one to eighteen carbon atoms. Polymeric properties depended upon the organic moieties; polymers were fusible, tractable, and flexible when the organic moieties contained six or more carbon atoms. Soluble polymers were prepared by using mixtures of symmetrical and unsymmetrical phosphinates. One polymer, poly{bis[n-butyl(benzyl)phosphinato]di-n-octylphosphinatoalane}, exhibited a degree of polymerization greater than 1000 and an exceptionally high intrinsic viscosity of 37 dl/g. The properties of the different polymers are discussed, and feasible structures are proposed.     

Mass spectral fragmentation mechanisms of some dibenzo[c,f][1,2] diazepines

The fragmentation mechanisms of 11H-dibenzo[c,f][1,2]diazepine (I), its 3,8-dichloro derivative (II), 3,8-dichlorodibenzo[c,f] [1,2]diazepin-11-one (III) and 3,8-dichloro-11H-dibenzo-[c,f][1,2]diazepin-N-oxide (IV) are discussed. The initial loss of molecular nitrogen is characteristic of I, II and III. Compound IV has a strong molecular ion, that competitively eliminates cither NO or Cl- and N₂O. The common radical ion, m/166 e present in the mass spectra of I, fluorene, 2-methyl-9,10-anthraquinone and 2-methylbenzo[c]cinnoline, appears to be formed in different states.     

A “Push–Pull” Stabilized Phosphinidene Supported by a Phosphine-Functionalized β-Diketiminato Ligand

The use of a bis(diphenyl)phosphine functionalized β-diketiminato ligand, [HC{(CH₃)C}₂{(ortho-[P(C₆H₅)₂]₂C₆H₄)N}₂]⁻ (PNac), as a support for germanium(II) and tin(II) chloride and phosphaketene compounds, is described. The conformational flexibility and hemilability of this unique ligand provide a versatile coordination environment that can accommodate the electronic needs of the ligated elements. For example, chloride abstraction from [(PNac)ECl] (E=Ge, Sn) affords the cationic germyliumylidene and stannyliumylidene species [(PNac)E]⁺ in which the pendant phosphine arms associate more strongly with the Lewis acidic main group element centers, providing further electronic stabilization. In a similar fashion, chemical decarbonylation of the germanium phosphaketene [(PNac)Ge(PCO)] with tris(pentafluorophenyl)borane affords a “push–pull” stabilized phosphinidene in which one of the phosphine groups of the ligand backbone associates with the low valent phosphinidene center.     

Synthesis and metal complexation studies of [2n]thiacalix[m]arene[m]pyrazine

Novel [2_n]thiacalixarenepyrazine and [2_n]thiacalixarenetriazine systems were synthesised by one-pot S_NAr reactions. A screening of the metal-complexing ability of [2₆]hexathiacalix[3]arene[3]pyrazine revealed its affinity for Cu^I, Cu^II and Ag^I metal salts.     

The New Fluoro‐tris(pentafluoroethyl)borate Anion [(C2F5)3BF]—, Unexpected Formation of [(C2F5)3BH]— as a By‐Product. Das neue Fluoro‐tris(pentafluoroethyl)borat Anion [(C2F5)3BF]—, unerwartete Bildung des Nebenprodukts [(C2F5)3BH]—

Dimethylamine‐tris(pentafluoroethyl)borane (C₂F₅)₃B · NHMe₂ ( 1 ) has been obtained from C₂F₅I, Br₂BNMe₂ and tris(diethylamino)phosphane in sulfolane. Alkylation using CH₃I/KOH yielded the trimethylamine‐tris(pentafluoroethyl)borane (C₂F₅)₃B · NMe₃ ( 2 ). Compound 2 reacts with NEt₃×3HF at 200—204 °C under replacement of the trimethylamine ligand to form the novel fluoro‐tris(pentafluoroethyl)borate anion [(C₂F₅)₃BF]^— ( 3 ) in good yield. Side products are the hydroxy‐tris(pentafluoroethyl)borate [(C₂F₅)₃BOH]^— ( 4 ) and the hydrido‐tris(pentafluoroethyl)borate [(C₂F₅)₃BH]^— ( 5 ).     

Solvothermal Synthesis and Crystal Structures of Two Thioantimonate(V) Compounds with the [SbS4]3— Anion Acting as a Monodentate Ligand: [Mn(C6H18N4)(C6H19N4)]SbS4 and [Mn(C6H14N2)3]2[Mn(C6H14N2)2(SbS4)2]·6H2O

The two novel thioantimonate(V) compounds [Mn(C₆H₁₈N₄)(C₆H₁₉N₄)]SbS₄ ( I ) and [Mn(C₆H₁₄N₂)₃][Mn(C₆H₁₄N₂)₂(SbS₄)₂]·6H₂O ( II ) were synthesized under solvothermal conditions by reacting elemental Mn, Sb and S in the stoichiometric ratio in 5 ml tris(2‐aminoethyl)amine (tren) at 140 °C or chxn (trans‐1, 2‐diaminocyclohexane, aqueous solution 50 %) at 130 °C. Compound I crystallises in the triclinic space group P1¯, a = 9.578(2), b = 11.541(2), c = 12.297(2)Å, α = 62.55(1), β = 85.75(1), γ = 89.44(1)°, V = 1202.6(4)ų, Z = 2, and II in the monoclinic space group C2/c, a = 32.611(2), b = 13.680(1), c = 19.997(1)Å, β = 117.237(5)°, V = 7931.7(8)ų, Z = 4. In I the Mn²⁺ cation is surrounded by one tetradentate tren molecule, one protonated tren acting as a monodentate ligand and a monodentate [SbS₄]^3— anion yielding a distorted octahedral environment. In II one unique Mn²⁺ ion is in an octahedral environment of three bidentate chxn molecules and the second independent Mn²⁺ ion is coordinated by two chxn ligands and two monodentate [SbS₄]^3— units leading to a distorted octahedral surrounding. The compounds were investigated and characterized with thermal and spectroscopic methods.     

Molecular building blocks for solid‐state chalcogenides: solvothermal synthesis of [Mn(en)3]Te4 and [Fe(en)3]2(Sb2Se5)

Two new molecular metal chalcogenides, tris­(ethyl­enedi­amine‐N,N′)­manganese(II) tetratelluride, [Mn(C₂H₈N₂)₃]Te₄, (I), and bis­[tris­(ethyl­enedi­amine‐N,N′)­iron(II)] penta­seleno­diantimonate(III), [Fe(C₂H₈N₂)₃]₂(Sb₂Se₅), (II), containing the isolated molecular building blocks Te₄^2? and Sb₂Se₅^4?, have been synthesized by solvothermal reactions in an ethyl­enedi­amine solution at 433 K. The anion Te₄^2? in (I) is a zigzag oligometric chain with Te—Te bond lengths in the range 2.709–2.751 Å. There is a very short contact [3.329 (1) Å] between a pair of neighboring Te₄^2? anions. In (II), each Sb atom is surrounded by three Se atoms to give a tripodal coordination. One of the three independent Se atoms is a μ₂‐bridging ligand between two Sb atoms; the other two are terminal.     

Copper(I)-anilide complex [Na(phen)3][Cu(NPh2)2]: an intermediate in the copper-catalyzed N-arylation of N-phenylaniline

Complex [Na(phen)₃][Cu(NPh₂)₂] ( 2 ), containing a linear bis(N‐phenylanilide)copper(I) anion and a distorted octahedral tris(1,10‐phenanthroline)sodium counter cation, has been isolated from the catalytic C? N cross‐coupling reaction with the CuI/phen/tBuONa (phen=1,10‐phenanthroline) catalytic system. Complex 2 can react with 4‐iodotoluene to produce 4‐methyl‐N,N‐diphenylaniline ( 3 a ) with 70.6 % yield. In addition, 2 can work as an effective catalyst for C? N coupling under the same reaction conditions, thus indicating that 2 is the intermediate of the catalytic system. Both [Cu(NPh₂)₂]^? and [Cu(NPh₂)I]^? have been observed by in situ electron ionization mass spectrometry (ESI‐MS) under catalytic reaction conditions, thus confirming that they are intermediates in the reaction. A catalytic cycle has been proposed based on these observations. The molecular structure of 2 has been determined by single‐crystal X‐ray diffraction analysis.     

Dimethylaminoalane,H3 − n Al[N(CH3)2]n,n = 1, 2, 3 Kristallstrukturen und Molekülspektren

Dimethylaminoalanes, H_{3 ? n}Al[N(CH₃)₂]_n, n = 1, 2, 3; Crystal Structures and Molecular Spectra The X-ray crystal structure analyses of dimethylaminoalane (I), bis(dimethylamino)alane, and tris(dimethylamino)alane are reported and the molecular spectra of these compounds are discussed. I is trimeric and exists as sixmembered ring of a chair-conformation. II and III are dimeric and build up planar four-membered rings.     

Bimetallic assemblies, [Ni(en)2]3[M(CN)6]2·3H2O (en = H2NCH2CH2NH2; M = Fe,Co)

The reaction between tris(ethyl­enedi­amine)­nickel(II) cations and hexa­cyanometallate(III) anions (M = Fe, Co) yields ordered bimetallic assemblies, catena‐poly­[[tris­(ethyl­enedi­amine)­nickel‐bis(μ‐hexa­cyano­iron‐N,N′)] trihydrate] and catena‐poly­[[tris­(ethyl­enedi­amine)­nickel‐bis(μ‐hexa­cyano­cobalt‐N,N′)] trihydrate], [{Ni(C₂H₈N₂)₂}₃{M(CN)₆}₂]·3H₂O, in which both cis and trans [Ni(en)₂] and [M(CN)₆] moieties are linked to give S‐shaped Ni–NC–M–CN–Ni–NC–M–CN–Ni units which are cross­linked to give ribbons parallel to the b axis. The two compounds are isomorphous with mean metal–ligand distances Fe—C = 1.940 (3), Co—C = 1.844 (3) and Ni—N = 2.102 (2) Å for the iron, and 2.105 (3) Å for the cobalt compound. These compounds appear to be identical with those formulated as [Ni(en)₂]₃[M(CN)₆]₂·2H₂O [Ohba, Maruona, Okawa, Enoki & Latour (1994). J. Am. Chem. Soc. 116 , 11566–11567; Ohba, Fukita & Okawa (1997). J. Chem. Soc. Dalton Trans. pp. 1733–1737] which were indexed on a smaller unit cell and described as disordered.     

New polyfunctional silicon-containing amines C6[CH2CH2SiMe(OCH2CH2NR2)2]6 (R = H,Me) and their reactions with cobalt(ii) chloride and dicobalt octacarbonyl

Hexakis[bis(2-aminoethoxy)methylsilylethyl]benzene and hexakis[bis(N,N-dimethyl-2-aminoethoxy)methylsilylethyl]benzene C₆[(NR₂CH₂CH₂O)₂SiMeCH₂CH₂]₆ (4, R = H; 5, R = Me) were prepared from hexakis(methyldichlorosilylethyl)benzene C₆(Cl₂MeSiCH₂CH₂)₆ and 2-aminoethanol or N,N-dimethyl-2-aminoethanol, respectively. Compounds 4 and 5 react with anhydrous cobalt (ii) chloride to give poorly soluble dodecachloro{hexakis[bis(2-aminoethoxy)methylsilylethyl]benzene}hexacobalt and dodecachloro{hexakis[bis(N,N-dimethyl-2-aminoethoxy)methylsilylethyl]benzene}hexacobalt {Co₆[(NR₂CH₂CH₂O)₂SiMeCH₂CH₂]₆C₆}Cl₁₂ (R = H or Me), respectively. Polyfunctional amine 4 reacts with dicobalt octacarbonyl to produce hexakis[bis(2-aminoethoxy)methylsilylethyl]benzenedicobalt(ii) tetrakis(tetracarbonylcobaltate) {Co₂[(NH₂CH₂CH₂O)₂SiMeCH₂CH₂]₆C₆}[Co(CO)₄]₄. N,N-Dimethyl-substituted polyfunctional amine 5 is lowly reactive in the reaction with Co₂(CO)₈, whereas the simplest model of this compound, viz., bis(N,N-dimethyl-2-aminoethoxy)dimethylsilane (NMe₂CH₂CH₂O)₂SiMe₂, slowly reacts with Co₂(CO)₈ to give tris[bis(N,N-dimethyl-2-aminoethoxy)dimethylsilane]cobalt(ii) bis(tetracarbonylcobaltate) {Co[(NMe₂CH₂CH₂O)₂SiMe₂]₃}[Co(CO)₄]₂. Thermal decomposition and transformations of the resulting complexes under the action of oxygen and water were studied.     

Hydrate isomerism in [Cu(en)2(H2O)1.935]2[Fe(CN)6]·4H2O

The title compound, bis[di­aqua­bis­(ethyl­enedi­amine‐κ²N,N′)copper(II)­] hexa­cyano­iron(II) tetrahydrate, [Cu(C₂H₈N₂)₂(H₂O)_1.935]₂[Fe(CN)₆]·4H₂O, was crystallized from an aqueous reaction mixture initially containing CuSO₄, K₃[Fe(CN)₆] and ethyl­enedi­amine (en) in a 3:2:6 molar ratio. Its structure is ionic and is built up of two crystallographically different cations, viz. [Cu(en)₂(H₂O)₂]²⁺ and [Cu(en)₂(H₂O)_1.87]²⁺, there being a deficiency of aqua ligands in the latter, [Fe(CN)₆]⁴⁻ anions and disordered solvent water mol­ecules. All the metal atoms lie on centres of inversion. The Cu atom is octahedrally coordinated by two chelate‐bonded en mol­ecules [mean Cu—N = 2.016 (2) Å] in the equatorial plane, and by axial aqua ligands, showing very long distances due to the Jahn–Teller effect [mean Cu—O = 2.611 (2) Å]. In one of the cations, significant underoccupation of the O‐atom site is observed, correlated with the appearance of a non‐coordinated water mol­ecule. This is interpreted as the partial contribution of a hydrate isomer. The [Fe(CN)₆]⁴⁻ anions form quite regular octahedra, with a mean Fe—C distance of 1.913 (2) Å. The dominant intermolecular interactions are cation–anion O—H⋯N hydrogen bonds and these inter­actions form layers parallel to (001).