Tetrakis(μ‐triisopropylsilanethiolato)‐1:2κ4S:S;2:3κ4S:S‐bis(triisopropylsilanethiolato)‐1κS,3κS‐trizinc(II)

The title compound, [Zn₃(C₉H₂₁SiS)₆] or [(ⁱPr₃SiS)Zn(μ‐SSiⁱPr₃)₂Zn(μ‐SSiⁱPr₃)₂Zn(SSiⁱPr₃)], is the first structurally characterized homoleptic silanethiolate complex of zinc. A near‐linear arrangement of three Zn^II ions is observed, the metals at the ends being three‐coordinate with one terminally bound silanethiolate ligand. The central Zn^II ion is four‐coordinate and tetrahedral, with two bridging silanethiolate ligands joining it to each of the two peripheral Zn^II ions. The nonbonding intermetallic distances are 3.1344 (11) and 3.2288 (12) Å, while the Zn...Zn...Zn angle is 172.34 (2)°. A trimetallic silanethiolate species of this type has not been previously identified by X‐ray crystallography for any element.     

Behavior of 3(2‐pyridinylmethylene)‐5‐aryl‐2(3H)‐furanones and 3(3‐pyridinylmethylene)‐5‐aryl‐2(3H)‐furanones as alkylating agents: A comparative study

3(2‐pyridinylmethylene)‐5‐aryl‐2(3H)‐furanones and 3(3‐pyridinylmethylene)‐5‐aryl‐2(3H)‐furanones were prepared as a mixture of (E) and (Z) stereoisomers by condensing pyridine‐2‐carboxaldehyde and pyridine‐3‐carboxaldehyde with 3‐aroylpropionic acids. The reaction of the furanones 6 and 7 with anhydrous aluminium chloride in benzene led to the formation of 4,4‐diaryl‐1‐(2‐pyridinyl)but‐1,3‐diene ( 8 ) and 4,4‐diaryl‐1‐(3‐pyridinyl)but‐1,3‐diene ( 9 ) as mixtures of geometrical (E,E‐ and E,Z‐) stereoisomers via an intermolecular alkylation mode. When the reaction was carried out in tetrachloroethane as a solvent, the reaction of 6 gave 5‐arylquinoline‐7‐carboxylic acid via intramolecular alkylation mode. This may be considered as a novel method for the synthesis of quinoline derivatives. J. Heterocyclic Chem., (2011).     

Di‐μ‐acesulfamato‐κ3N,O:O;κ3O:N,O‐bis[(acesulfamato‐κ2N,O)bis(3‐methylpyridine)cadmium(II)]

In the structure of the title compound, [Cd₂(C₄H₄NO₄S)₂(C₆H₇N)₂], the dinuclear Cd^II complex is located on a twofold axis with two Cd²⁺ ions bridged by two oxide O atoms. Each Cd²⁺ ion is additionally coordinated in an equatorial plane by two N and three O atoms of the acesulfamate ligands and axially by two N atoms of the 3‐methylpyridine ligands, resulting in a distorted pentagonal bipyramidal coordination. We present here an example of a supramolecular assembly based on hydrogen bonds in a mixed‐ligand metal complex; intermolecular C—H...O hydrogen bonds give rise to R₄⁴(40) rings, which lead to one‐dimensional chains.     

(2S,3S)‐2,6‐Dimethylheptane‐1,3‐diol,the oxygenated side chain of 22(S)‐hydroxycholestrol,and its synthetic precursor (R)‐4‐benzyl‐3‐[(2R,3S)‐3‐hydroxy‐2,6‐dimethylheptanoyl]‐1,3‐oxazolidin‐2‐one

(2S,3S)‐2,6‐Dimethylheptane‐1,3‐diol, C₉H₂₀O₂, (I), was synthesized from the ketone (R)‐4‐benzyl‐3‐[(2R,3S)‐3‐hydroxy‐2,6‐dimethylheptanoyl]‐1,3‐oxazolidin‐2‐one, C₁₉H₂₇NO₄, (II), containing C atoms of known chirality. In both structures, strong hydrogen bonds between the hydroxy groups form tape motifs. The contribution from weaker C—H...O hydrogen bonds is much more evident in the structure of (II), which furthermore contains an example of a direct short Osp³...Csp² contact that represents a usually unrecognized type of intermolecular interaction.     

Bis(2‐amino‐1H‐benzimidazol‐3‐ium) tetrakis(μ‐but‐2‐enoato)‐κ4O:O′;κ3O,O′:O;κ3O:O,O′‐bis[bis(but‐2‐enoato‐κ2O,O′)holmium(III)]

The title ionic compound, (C₇H₈N₃)₂[Ho₂(C₄H₅O₂)₈], is constructed from two almost identical independent centrosymmetric anionic dimers balanced by two independent 2‐amino‐1H‐benzimidazol‐3‐ium (Habim⁺) cations. The asymmetric part of each dimer is made up of one Ho^III cation and four crotonate (crot or but‐2‐enoate) anions, two of them acting in a simple η²‐chelating mode and the remaining two acting in two different μ₂:η² fashions, viz. purely bridging and bridging–chelating. Symmetry‐related Ho^III cations are linked by two Ho—O—Ho and two Ho—O—C—O—Ho bridges which lead to rather short intracationic Ho...Ho distances [3.8418 (3) and 3.8246 (3) Å]. In addition to the obvious Coulombic interactions linking the cations and anions, the isolated [Ho₂(crot)₈]²⁻ and Habim⁺ ions are linked by a number of N—H...O hydrogen bonds, in which all N—H groups of the cation are involved as donors and all (simple chelating) crot O atoms are involved as acceptors. These interactions result in compact two‐dimensional structures parallel to (110), which are linked to each other by weaker π–π contacts between Habim⁺ benzene groups.     

Poly(3‐hexylthiophene)‐b‐poly(3‐cyclohexylthiophene): Synthesis,microphase separation,thin film transistors,and photovoltaic applications

We report the synthesis, characterization, microphase separation, field‐effect charge transport, and photovoltaic properties of regioregular poly(3‐hexylthiophene)‐b‐poly(3‐cyclohexylthiophene) (P3HT‐b‐P3cHT). Two compositions of P3HT‐b‐P3cHT (HcH63 and HcH77) were synthesized with weight‐average molecular weights of 155,500 and 210,800 and polydispersity indices of 1.45 and 1.57, respectively. Solvent‐casted HcH77 was found to self‐assemble into nanowires with a width of 12.5 ± 0.9 nm and aspect ratios of 50–120, as observed by TEM imaging. HcH77 and HcH63 annealed 280 °C were observed by small angle X‐ray scattering (SAXS) and wide angle X‐ray scattering (WAXS) to be microphase‐separated with characteristic length scales of 17.0–21.7 nm. The microphase‐separated domains were shown to be crystalline with interlayer backbone (100) d‐spacings of 1.69 and 1.40 nm, which correspond to the P3HT and P3cHT blocks, respectively. Field‐effect transistors fabricated from P3HT‐b‐P3cHT thin films showed a mobility of holes (0.0019 cm²/Vs) which is independent of thermal annealing. Bulk heterojunction solar cells based on HcH77/fullerene (PC₇₁BM) blend thin films had a maximum power conversion efficiency of 2.45% under 100 mW/cm² AM1.5 solar illumination in air. These results demonstrate that all‐conjugated block copolymers are suitable semiconductors for applications in field‐effect transistors and bulk heterojunction solar cells. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 614–626, 2010     

A tetranuclear copper(II) cluster: bis(μ‐4‐chlorobenzoato‐κ2O:O′)(4‐chlorobenzoato‐κ2O,O′)(4‐chlorobenzoato‐κO)tetrakis(μ3‐2‐pyridylmethanolato‐κ4N,O:O:O)tetracopper(II)

The title compound, [Cu₄(C₇H₄ClO₂)₄(C₆H₆NO)₄], consists of isolated tetranuclear clusters, where the Cu²⁺ cations are five‐ and sixfold coordinated by O atoms from the 4‐chlorobenzoate anions and by pyridine N and methanolate O atoms from bidentate 2‐pyridylmethanolate ligands. While three Cu atoms are six‐coordinated by an NO₅ donor set forming distorted octahedra, the fourth Cu atom is five‐coordinated by an NO₄ donor set forming a distorted tetragonal–pyramidal coordination around the Cu atom. The nucleus is a deformed cubane‐like Cu₄O₄ structure, with Cu...Cu distances in the range 3.0266 (11)–3.5144 (13) Å.     

Preparation of (S,S)‐Fmoc‐β2hIle‐OH, (S)‐Fmoc‐β2hMet‐OH,and (S)‐Fmoc‐β2hTyr(tBu)‐OH for Solid‐Phase Syntheses of β2‐ and β2/β3‐Peptides

The preparation of three new N‐Fmoc‐protected (Fmoc=[(9H‐fluoren‐9‐yl)methoxy]carbonyl) β²‐homoamino acids with proteinogenic side chains (from Ile, Tyr, and Met) is described, the key step being a diastereoselective amidomethylation of the corresponding Ti‐enolates of 3‐acyl‐4‐isopropyl‐5,5‐diphenyloxazolidin‐2‐ones with CbzNHCH₂OMe/TiCl₄ (Cbz=(benzyloxy)carbonyl) in yields of 60–70% and with diastereoselectivities of >90%. Removal of the chiral auxiliary with LiOH or NaOH gives the N‐Cbz‐protected β‐amino acids, which were subjected to an N‐Cbz/N‐Fmoc (Fmoc=[(9H‐fluoren‐9‐yl)methoxy]carbonyl) protective‐group exchange. The method is suitable for large‐scale preparation of Fmoc‐β²hXaa‐OH for solid‐phase syntheses of β‐peptides. The Fmoc‐amino acids and all compounds leading to them have been fully characterized by melting points, optical rotations, IR, ¹H‐ and ¹³C‐NMR, and mass spectra, as well as by elemental analyses.     

1, 3, 4, 4'‐Tetra(triphenylphosphanimin)‐2‐iodo‐2‐butenal‐4‐carboniumiodid, [O=C(NPPh3)C(I)=C(NPPh3)‐C(NPPh3)2]+I‐

Pale yellow single crystals of [O=C(NPPh₃)C(I)=C(NPPh₃)‐C(NPPh₃)₂]⁺I^‐·1.5 thf ( 1 ·1.5 thf) have been obtained by the reaction of INPPh₃ with thallium in thf suspension. They are characterized by IR spectroscopy and by a crystal structure determination. 1 ·1.5 thf crystallizes in the monoclinic space group P2₁/n, Z = 4, lattice dimensions at ‐83?C: a = 1101.7(1), b = 3449.0(2), c = 2000.4(1) pm, β = 104.88(1)?, R₁ = 0.0382. 1 can be understood as a cationic variation of (Z)‐2‐butenale in which all H atoms are substituted by triphenylphosphoraneimine residues and by a iodine atom, respectively.     

(1,3‐Dimethylimidazolidine‐2‐selone‐κSe)bis(1,10‐phenanthroline‐κ2N,N′)copper(II) bis(perchlorate) and bis(2,2′‐bipyridyl‐κ2N,N′)(imidazolidine‐2‐thione‐κS)copper(II) bis(perchlorate)

In the first title salt, [Cu(C₁₂H₈N₂)₂(C₅H₁₀N₂Se)](ClO₄)₂, the Cu^II centre occupies a distorted trigonal–bipyramidal environment defined by four N donors from two 1,10‐phenanthroline (phen) ligands and by the Se donor of a 1,3‐dimethylimidazolidine‐2‐selone ligand, with the equatorial plane defined by the Se and by two N donors from different phen ligands and the axial sites occupied by the two remaining N donors, one from each phen ligand. The Cu—N distances span the range 1.980 (10)–2.114 (11) Å and the Cu—Se distance is 2.491 (3) Å. Intermolecular π–π contacts between imidazolidine rings and the central rings of phen ligands generate chains of cations. In the second salt, [Cu(C₁₀H₈N₂)₂(C₃H₆N₂S)](ClO₄)₂, the Cu^II centre occupies a similar distorted trigonal–bipyramidal environment comprising four N donors from two 2,2′‐bipyridyl (bipy) ligands and an S donor from an imidazolidine‐2‐thione ligand. The equatorial plane is defined by the S donor and two N donors from different bipy ligands. The Cu—N distances span the range 1.984 (6)–2.069 (7) Å and the Cu—S distance is 2.366 (3) Å. Intermolecular π–π contacts between imidazolidine and pyridyl rings form chains of cations. A major difference between the two structures is due to the presence in the second complex of two N—H...O hydrogen bonds linking the imidazolidine N—H hydrogen‐bond donors to perchlorate O‐atom acceptors.     

Metalated 1, 3‐Azaphospholes: η1‐(1H‐1, 3‐Benzazaphosphole‐P)M(CO)5 and μ2‐[(1, 3‐Benzazaphospholide‐P)(cyclopentadienide)nickel] Complexes

1H‐1, 3‐Benzazaphospholes react with M(CO)₅(THF) (M = Cr, Mo, W) to give thermally and relatively air stable η¹‐(1H‐1, 3‐Benzazaphosphole‐P)M(CO)₅ complexes. The ¹H‐ and ¹³C‐NMR‐data are in accordance with the preservation of the phosphaaromatic π‐system of the ligand. The strong upfield ³¹P coordination shift, particularly of the Mo and W complexes, forms a contrast to the downfield‐shifts of phosphine‐M(CO)₅ complexes and classifies benzazaphospholes as weak donor but efficient acceptor ligands. Nickelocene reacts as organometallic species with metalation of the NH‐function. The resulting ambident 1, 3‐benzazaphospholide anions prefer a μ₂‐coordination of the η⁵‐CpNi‐fragment at phosphorus to coordination at nitrogen or a η³‐heteroallyl‐η⁵‐CpNi‐semisandwich structure. This is shown by characteristic NMR data and the crystal structure analysis of a η⁵‐CpNi‐benzazaphospholide. The latter is a P‐bridging dimer with a planar Ni₂P₂ ring and trans‐configuration of the two planar heterocyclic phosphido ligands arranged perpendicular to the four‐membered ring.     

catena‐Poly[bis(μ‐2,2′‐bipyridin‐6‐olato)‐κ3N,N′:O;O:N,N′‐dicopper(I,II) [[tetrafluoridoniobium(V)]‐μ‐oxido]]

A novel copper–niobium oxyfluoride, {[Cu₂(C₁₀H₇N₂O)₂][NbOF₄]}_n, has been synthesized by a hydrothermal method and characterized by elemental analysis, EDS, IR, XPS and single‐crystal X‐ray diffraction. The structural unit consists of one C₂‐symmetric [NbOF₄]⁻ anion and one centrosymmetric coordinated [Cu₂(obpy)₂]⁺ cation (obpy is 2,2′‐bipyridin‐6‐olate). In the [NbOF₄]⁻ anion, each Nb^V metal centre is five‐coordinated by four F atoms and one O atom in the first coordination shell, forming a square‐pyramidal coordination geometry. These square pyramids are then further connected to each other via trans O atoms [Nb—O = 2.187 (3) Å], forming an infinite linear {[NbOF₄]⁻}_n polyanion. In the coordinated [Cu₂(obpy)₂]⁺ cation, the oxidation state of each Cu site is disordered, which is confirmed by the XPS results. The disordered Cu sites are coordinated by two N atoms and one O atom from two different obpy ligands. The [NbOF₄]⁻ and [Cu₂(obpy)₂]⁺ units are assembled via weak C—H...F hydrogen bonds, resulting in the formation of a three‐dimensional supramolecular structure. π–π stacking interactions between the pyridine rings [centroid–centroid distance = 3.610 (2) Å] may further stabilize the crystal structure.     

Diiodobis(4‐methylpentan‐2‐onato‐C4,O)tin(IV): a comparison with diiodobis(3‐methoxy‐3‐oxopropyl‐C,O)tin(IV)

The title compound, [SnI₂(C₆H₁₁O)₂], contains a six‐coordinate tin centre as a consequence of intramolecular Sn—O interactions. The Sn—O bond lengths range between 2.428 (4) and 2.439 (4) Å.     

A pentanuclear bimetallic complex of manganese(II) and aluminium(III) ions: tetra‐μ2‐iodido‐iodidobis(μ3‐2‐methoxyethanolato)bis(μ2‐2‐methoxyethanolato)dimethyl(tetrahydrofuran‐κO)aluminium(III)tetramanganese(II)

The molecule of the title compound, [Mn₄Al(CH₃)₂(C₃H₇O₂)₄I₅(C₄H₈O)], contains one Al^III and four Mn^II ions. Two Mn atoms are five‐coordinate in the form of a trigonal bipyramid or a square pyramid. The two other Mn atoms are six‐coordinate with an octahedral geometry. The fourcoordinate Al atom is linked to the manganese core by μ‐O_alkoxo bridges, forming an almost planar five‐membered ring.     

(σ3,λ5)‐phosphoranes versus (σ3,λ3)‐thiaphosphiranes: Quantum chemical investigation of products of phosphaalkene sulfurization

By sulfurization of phosphaalkenes ( a ) either (σ³,λ⁵)‐phosphoranes ( b ) or (σ³,λ³)‐thiaphosphiranes ( c ) are formed. In this study, Density Functional Theory (DFT) and coupled cluster (CCSD(T)) calculations have been carried out for model and experimental structures of (σ³,λ⁵)‐phosphoranes and (σ³,λ³)‐thiaphosphiranes to elucidate the factors influencing relative stabilities of b and c . According to the results of quantum chemical calculations, sterically bulky substituents make the phosphorane form more favored. Conversely, electronic effects of the most substituents provide higher stability for thiaphosphirane isomers. The only exception has been found in the cases where the substituent at the phosphorus atom possesses π‐donor and σ‐acceptor properties (e.g., in the case of amino group) and the substituents at carbon atom exhibit σ‐donor/π‐acceptor effects (e.g., silyl groups). The stability of the cyclic form c decreases further, if the substituents at the carbon atom are amino groups. In this case, a quite unusual structure has been theoretically predicted, which is considerably different from those of the hitherto known phosphoranes. It indicates a pyramidal configuration at the phosphorus atom and can be conventionally presented as a donor–acceptor adduct of diaminocarbene with thioxophosphine. © 2012 Wiley Periodicals, Inc.     

Polymeric diaqua(μ2‐2,2′‐bipyrimidinyl‐κ4N1,N1′:N3,N3′)‐di‐μ3‐hydroxy‐bis(μ5‐benzene‐1,3,5‐tricarboxylato‐κ5O1:O2:O3:O3:O5)tetracobalt(II) dihydrate

The structure of the title compound, [Co₄(C₉H₃O₆)₂(OH)₂(C₈H₆N₄)(H₂O)₂]·2H₂O, contains three separate species, namely the μ₅‐bridging C₉H₃O₆^3? anion, the doubly chelating and therefore μ₂‐bridging C₈H₆N₄ ligand (bi­pyrimidine, BPM), and the dihydrated di­aqua­di­hydroxy tetranuclear cationic cluster, [Co₄(OH^?)₂(H₂O)₂]⁶⁺·2H₂O, which lies on a crystallographic centre of symmetry, as does the BPM ligand with, in this case, the centre of symmetry coincident with the midpoint of the C—C bond joining the six‐membered rings. Within the cation cluster, the Co atoms of one pair are five‐coordinate and those of the other six‐coordinate.     

A three‐dimensional coordination polymer based on the Zn4(μ3‐OH)2 unit: poly[[(μ4‐benzene‐1,4‐dicarboxylato)bis(μ3‐benzene‐1,4‐dicarboxylato)bis(μ3‐hydroxido)bis(1,10‐phenanthroline‐5,6‐dione)tetrazinc] dihydrate]

The title compound, {[Zn₄(C₈H₄O₄)₃(OH)₂(C₁₂H₆N₂O₂)₂]·2H₂O}_n, has been prepared hydrothermally by the reaction of Zn(NO₃)₂·6H₂O with benzene‐1,4‐dicarboxylic acid (H₂bdc) and 1,10‐phenanthroline‐5,6‐dione (pdon) in H₂O. In the crystal structure, a tetranuclear Zn₄(OH)₂ fragment is located on a crystallographic inversion centre which relates two subunits, each containing a [ZnN₂O₄] octahedron and a [ZnO₄] tetrahedron bridged by a μ₃‐OH group. The pdon ligand chelates to zinc through its two N atoms to form part of the [ZnN₂O₄] octahedron. The two crystallographically independent bdc²⁻ ligands are fully deprotonated and adopt μ₃‐κO:κO′:κO′′ and μ₄‐κO:κO′:κO′′:κO′′′ coordination modes, bridging three or four Zn^II cations, respectively, from two Zn₄(OH)₂ units. The Zn₄(OH)₂ fragment connects six neighbouring tetranuclear units through four μ₃‐bdc²⁻ and two μ₄‐bdc²⁻ ligands, forming a three‐dimensional framework with uninodal 6‐connected α‐Po topology, in which the tetranuclear Zn₄(OH)₂ units are considered as 6‐connected nodes and the bdc²⁻ ligands act as linkers. The uncoordinated water molecules are located on opposite sides of the Zn₄(OH)₂ unit and are connected to it through hydrogen‐bonding interactions involving hydroxide and carboxylate groups. The structure is further stabilized by extensive π–π interactions between the pdon and μ₄‐bdc²⁻ ligands.     

Two novel silver(I) coordination polymers: poly[(μ2‐2‐aminopyrimidine‐κ2N1:N3)bis(μ3‐thiocyanato‐κ3S:S:S)disilver(I)] and poly[(2‐amino‐4,6‐dimethylpyrimidine‐κN)(μ3‐thiocyanato‐κ3N:S:S)silver(I)]

2‐Aminopyrimidine (L1) and 2‐amino‐4,6‐dimethylpyrimidine (L2) have been used to create the two novel title complexes, [Ag₂(NCS)₂(C₄H₅N₃)]_n, (I), and [Ag(NCS)(C₆H₉N₃)]_n, (II). The structures of complexes (I) and (II) are mainly directed by the steric properties of the ligands. In (I), the L1 ligand is bisected by a twofold rotation axis running through the amine N atom and opposite C atoms of the pyrimidine ring. The thiocyanate anion adopts the rare μ₃‐κ³S coordination mode to link three tetrahedrally coordinated Ag^I ions into a two‐dimensional honeycomb‐like 6³ net. The L1 ligands further extend the two‐dimensional sheet to form a three‐dimensional framework by bridging Ag^I ions in adjacent layers. In (II), with three formula units in the asymmetric unit, the L2 ligand bonds to a single Ag^I ion in a monodentate fashion, while the thiocyanate anions adopt a μ₃‐κ¹N,κ²S coordination mode to link the AgL2 subunits to form two‐dimensional sheets. These layers are linked by N—H...N hydrogen bonds between the noncoordinated amino H atoms and both thiocyanate and pyrimidine N atoms.     

Tetra‐μ‐chloro‐1:2κ4Cl;1:3κ4Cl‐di­methyl‐2κC,3κC‐tetra­kis(tetra­hydro­furan)‐1κ2O,2κO,3κO‐chromium(II)dizinc(II)

The title compound, [CrZn₂(CH₃)₂Cl₄(C₄H₈O)₄], contains a central distorted octa­hedral Cr atom, located at an inversion center, bound to two tetra­hydro­furan ligands and four chloro ligands that bridge to two symmetry‐related tetra­hedral Zn atoms. The coordination around zinc is completed by methyl and tetra­hydro­furan ligands. This structure is compared with a previously reported complex of vanadium, and their differences in metric parameters are explained.     

Bis(μ‐3‐nitrobenzene‐1,2‐dicarboxyl­ato)‐κ8O1,O2:O2,O3;O3,O2:O2,O1‐bis­[triaqua­(2‐carboxy‐3‐nitro­benzoato‐κ2O,O′)lanthanum(III)] dihydrate

The title compound, [La₂(C₈H₃NO₆)₂(C₈H₄NO₆)₂(H₂O)₆]·2H₂O, consists of dimeric units related by an inversion center. The two La^III atoms are linked by two bridging bidentate carboxyl­ate groups and two monodentate carboxyl­ate groups. Each La^III atom is nine‐coordinated by six O atoms from five different carboxyl­ate groups and three from water mol­ecules. Hydrogen bonds between the water mol­ecules and between the solvent water and a carboxyl­ate O atom are observed in the structure. In the crystal packing, there are slipped π–π stacking inter­actions between the parallel benzene rings. Both hydrogen‐bonding and π–π inter­actions combine to stabilize the three‐dimensional supra­molecular network.