bluuebunny/crossref_metadata_2025 huggingface dataset:
Polysulfonylamine, CV. Die ersten N,N-disulfonylierten Sulfinsäureamide: Synthese und Kristallstrukturen von RS(O)-N(SO2Me)2 (R = Me, CCl3) / Polysulfonylamines, C V. The First N,N -Disulfonylated Sulfinic Amides: Synthesis and Crystal Stru ctures of RS(O)-N(SO2Me)2 (R = Me, CCl3)
Authors: Näveke Martina , Blaschette Armand , Jones Peter G.
Published: February 2015

The novel sulfinamides RS(O) -N(SO2Me)2, where R = Me (1a) or CCl3 (1b), were obtained by treating the corresponding sulfinyl chlorides with Me3SiN(SO2Me)2 or AgN-(SO2Me)2, respectively. A presumedly ionic 1:1 adduct of 1b with 4-dimethylaminopyridine was isolated and analytically characterized. In the crystals of 1a (monoclinic, space group P21/c) and 1b (monoclinic, P21/c) , the molecules feature approximately planar NS3 moieties, unusually long S(O) -N bonds and, in the case of 1b, an extremely long S(O) -C bond [for la and 1b, in order: sum of bond angles at nitrogen 359.5 and 357.1°, S(O) -N 178.2(2) and 173.6(2) pm, S(O) -C 178.8(2) and 194.1(2) pm]. In both molecular structures, an attractive S(O) ··· O 1,4-interaction leads to a 7.3° discrepancy in the S(O) -N -SO2 angles. The crystal packing of 1a displays a tape (double-chain) motif generated by two prominent intermolecular C -H ··· O interactions involving one MeSO2 group and the sulfinyl oxygen atoms of two adjacent molecules, whereas in 1b the molecules are associated into parallel chains via a bonding Cl ⋯ O(sulfonyl) interaction.
Kristallstrukturen, Schwingungsspektren und Normalkoordinaten- analysen von trans-[OsO2(ox)2]2– und trans-[OsO2(mal)2]2–/ Crystal Structures, Vibrational Spectra and Normal Coordinate Analyses of trans-[OsO2(ox)2]2– and trans -[OsO2(mal)2]2–
Authors: Strueß A. , Preetz W.
Published: February 2015

The crystal structures of trans-(Ph4P)2[OsO2(ox)2] (monoclinic, space group P21/n, a = 12.281(2), b = 14.5440(13), c = 13.9810(12) Å, β = 100.000(8)°, Z = 2) and trans- (n-Bu4N)2[OsO2(mal)2] (triclinic, space group P1̄, a = 10.365(4),b = 10.707(3), c - 11.473(5) A, a = 73.00(2), β = 64.44(3), 7 = 82.55(3)°, Z = 1) have been determined by single crystal X-ray diffraction analysis. The IR and Raman spectra of these complexes were measured at room temperature. Based on the molecular parameters of the X-ray determinations normal coordinate analyses have been performed and the vibrations assigned. The valence force constants of [OsO2(ox)2]2- are fd(Os=O) = 6.7, fd(Os-O) = 2.9, fd(C-O) = 5.05, fd(C=O) = 11.2 and fd(C-C) = 4.7 mdyn/Å and of [OsO2(mal)2]2- fd(Os=O) = 6.7, fd(Os-O) = 2.9, fd(C-O) = 4.86, fd(C=O) =11.1 and fd(C-C) = 4.07 mdyn/Å.
Photooxidation of Dicyanoaurate(I) Induced by Metal-to-Ligand Charge Transfer Excitation
Authors: Kunkely Horst , Vogler Arad
Published: February 2015

The irradiation of [Au(CN)2]- in oxygen-saturated acetonitrile leads to photooxidation of Au(I). In the presence of additional chloride [Au(CN)2CL2]- is formed with φ= 0.5 x 10-4 at λirr = 254 nm. It is assumed that [Au(CN)2]- in its metal-to-ligand charge transfer state undergoes an excited state electron transfer to oxygen in the primary photochemical step.
Halogeno(acylphenolato)cobalt(III)-Verbindungen mit Trimethylphosphan-Liganden/ Halogeno(acylphenolato)cobalt(III) Compounds Containing Trimethylphosphane Ligands
Authors: Klein Hans-Friedrich , Haller Stefan , Sun Hongjian , Li Xiaoyan , Jung Thomas , Röhr Caroline , Flörke Ulrich , Haupt Hans-Jürgen
Published: February 2015

Complexes mer-CoH(CO-CR=CR′-O)(PMe3)3 react with haloalkanes RX (X = Br, I) or with acids HX (X = Cl, Br) under elimination of dihydrogen. In both reactions a change of configu­ration at the metal is brought about by directional steering through the hard/soft (acyl)enolato chelate ligands to form octahedral complexes mer-CoX(CO-CR=CR′-C))(PMe3)3 or sterically crowded ionic compounds [Co(CO-CR=CR′-O)(PMe3)4(3)]+ X-(X = ClO4) without opening of the (acyl)enolato chelate ring.
Crystal Structure and Spectroscopic Behaviour of a Binuclear Copper(II) Complex of Mefenamic Acid and Dimethylsulfoxide
Authors: Facchin G. , Torre M. H. , Kremer E. , Piro O. E. , Baran E. J.
Published: February 2015

The crystal structure of the binuclear Cu(II) complex [Cu(mef)2DMSO]2 (mef = deprotonated N-2,3-dimethylphenyl-anthranilic acid; DMSO = dimethylsulfoxide) has been determined by single-crystal X-ray diffractometry. It crystallizes in the triclinic space group P1̄ with Z = 1. IR and electronic spectra of the compound are also discussed briefly.
Zur Reaktion von 2,3-Dihydroimidazol-2-ylidenen mit Pentafluorpyridin: Carbene als Reaktionspartner in der nucleophilen aromatischen Substitution/ On the Reaction of 2,3-Dihydroimidazol-2-ylidenes with Pentafluoropyridine: Carbenes as Reactants in Nucleophilic Aromatic Substitution
Authors: Kuhn Norbert , Fahl Joanna , Boese Roland , Henkel Gerald
Published: February 2015

The 2,3-dihydro-1,3,4,5-tetraalkylimidazol-2-ylidenes 3 (R = Me, iso-Pr) react immediately with pentafluoropyridine to form the 2-tetrafluoropyridylimidazolium salts 4 in good yields. In contrast with the tetramethyl derivative 4a, alkyl fluoride is eliminated from the isopropyl salt 4b to give 1 -isopropyl-4,5-dimethyl-2-tetrafluoropyridylimidazole, which dimerises via hydrogen bridges in the solid state (7). The X-ray structures of 1,3-diisopropyl-4,5-dimethyl-2-tetrafluoropyridylimidazolium chloride (5) and 7 are reported.
Synthesis of Some Chromanone Derivatives and the Use of DNA in Evaluation of their Biological Activity
Authors: El-Desoky El-Sayed I. , El-Telbani Emad. M. , Hammad Mahmoud A.
Published: February 2015

6-Formyl-7-hydroxy-5-methoxy-2-pentamethylenechromanone (2) was prepared from the naturally occurring “Visnagin” and condensed with benzil, o-phenylenediamine and 3,4-diaminobenzophenone to give the corresponding imidazolylchromanone derivatives 3-5. Knoevenagel reaction of compound 2 with different active methylene compounds afforded benzodipyranone derivatives 12a - c which may be considered as analogues to the naturally occurring “Xanthyletin and Graveolone Compounds”. The structural formula of the new compounds were established by using different methods for their preparation in addition to the instrumental analyses. Some compounds in this study were biologically evaluated for their ability to bind to DNA.
[R2S-CH2-OTf]+ OTf– as a Reagent with an Optionally Mono-or Biselectrophilic Csp3 Center
Authors: Weiss Robert , Handke Matthias , Hampel Frank
Published: February 2015

Sulfonium salts [R2S-CH2-OTf]+ OTf- 1a,b are synthetically versatile 1,1-biselectrophiles featuring the sulfonio- and triflato-substituents as leaving groups of differential nucleofugic power. Reactions with a number of neutral nucleophiles |Nu yield a series of novel sulfoniom ethylated onium salts [R2S-CH2-Nu]2+ 2OTf- 2 - 8 under very mild conditions. Structures of salts 2a, 5a and 6b were confirm ed by X -ray analysis. With certain N -hetarenes exchange of both nucleofuges in la was achieved, yielding the symmetrical 1,1-bisonium salts 9 and 10. With pyridine(derivatives) selective substitution of the sulfoniofunction in 1,1-bisonium systems 2a and 5a was also realized. These reactions represent typical examples of nucleophilic substitutions at geminally bisonio substituted Csp3 centers, which we recently have introduced as a novel variant of Sɴ2 reactivity.
Notizen: Preparation, Structures and Optical Properties of [H3N(CH2)6NH3]BiX5 (X=I, Cl) and [H3N(CH2)6NH3]SbX5 (X=I, Br)
Authors: Mousdis G. A. , Papavassiliou G. C. , Terzis A. , Raptopoulou C. P.
Published: February 2015

The preparation, crystal structures and optical absorption spectra of [H3N(CH2)6NH3]BiX5 (X= I, Cl) and [H3N(CH2)6NH3]SbX5 (X =I, Br) are reported. The anions of the compounds consist of MX6-octahedra (M =Bi, Sb) sharing cisvertices in one-dimensional zig-zag chains. Because of their one-dimensional character, a blue shift of the excitonic absorption bands, in com parison to those of higher dim ensionality systems (MX3), is observed.
The Trichlorogermanite(II) Anion and its Gold(I) Complexes
Authors: Tripathi Upendra M. , Wegner Gerald L. , Schier Annette , Jockisch Alexander , Schmidbaur Hubert
Published: February 2015

Tetraphenylphosphonium trichlorogermanite(II) (1) has been prepared (as a reference compound) from Ph4P+ Cl- and GeCl2 (dioxane) in tetrahydronaphthalene. Its structure has been determined by single crystal X-ray methods. The lattice contains independent monomeric GeCl3
- anions (Ge-Cl distances between 2.290 and 2.320 Å, Cl-Ge-Cl angles between 95.33 and 98.27°). Treatment of (Ph3As)AuCl with GeCl2 (dioxane) affords (Ph3As)AuGeCl3 in high yields as a germylene insertion product (2). The complex is a dimer in the crystal with a short Au--Au contact of 2.9415(4) Å and bent As-Au-Ge axes [169.353(13)°]. The GeCl3 ligand has shorter Ge-Cl bonds [2.175 to 2.183 Å] and wider Cl-Ge-Cl angles than in the free anion [100.9 to 101.9°]. The analogous reaction with CH2 (AsPh2AuCl)2 leads only to a mono-insertion product in the form of a salt with {[CH2 (AsPh2)2Au]}2
2+ dications and two [ClAuGeCl3]- anions (3). In the lattice these three ions form a centrosymmetrical tetranuclear unit through short Au--Au contacts. The resulting z-shaped Au--Au--Au--Au chain has distances of 3.0499(6) (twice) and 3.1613(8) Å and angles of 118.833(8)° (twice). The geometry of the GeCl3 units is similar to that in 2. {(Et3N)Au[P(o-Tol)3]}+ PF6
- (4) was obtained as a by-product in several reactions with the bulky phosphine and where NEt3 was used as a base. The crystals contain two crystallographically independent cations with a similar core structure, but different conformations of the substituents. Both the P-Au and the N-Au bonds are elongated owing to steric effects.
Pyridine-Derived Tetrapodal Ligands with NO4 and NN4 Donor Sets
Authors: Schmidt Stefan , Omnès Laurent , Heinemann Frank W. , Kuhnigk Jörg , Krüger Carl , Grohmann Andreas
Published: February 2015

The Mg2+ assisted synthesis of a pyridine-derived tetraalcohol ligand with an NO4 donor set is described. 2,6-Diethylpyridine reacts cleanly with aqueous formaldehyde solution in the presence of 1 equivalent of MgSO4 hydrate in a pressurised vessel to give the quadruply hydroxymethylated product 2,6 -C5H3N[CMe(CH2OH)2]2 (1) as a crystalline solid. Two alkali/alkaline earth metal perchlorate adducts of 1 have been structurally characterised, viz. [(1)2 • LiClC4] (6) and [(1)2 • Ba(ClO4)2 ] (7). The ligand adopts a bridging coordination mode in both 6 (distorted tetrahedral coordination of Li+) and 7 (square prismatic coordination of Ba2+). The further derivatization of 1 leads to the tetratosylate (2) and the tetraazide (3), both of which have been obtained in pure form for the first time. Reduction of 3 gives the pentaamine ligand 2,6-C5H3N[CMe(CH2NH2)2]2 (4), isolated as the tetrakis(hydrobromide) salt 4 • 4 HBr. The presence of four ammonio substituents and an unprotonated pyridine nitrogen atom in the solid state has been unequivocally established by an X-ray structural analysis.
Metallkomplexe von biologisch wichtigen Liganden, CVI [1]. Metallkomplexe von Donor-substituierten Oxazolin-5-onen sowie von Bis(oxazolin-5-onen) / Metal Complexes of Biologically Important Ligands CVI [1], Metal Complexes of Donor Substituted Oxazolones and of Bis(oxazolones)
Authors: Prem Markus , Bauer Werner , Polbom Kurt , Beck Wolfgang
Published: February 2015

A series of chelate complexes 1-12 of Cu(II), Ni(II), Pd(II), and Ru(III) with the anion of 2-(2′-hydroxyphenyl)-5(4H)-oxazolone and with 2-(2′-aminophenyl)-5(4H)-oxazolone were prepared from metal salts or from chloro-bridged complexes [(R3P)MCl2]2 (M = Pd, Pt) and [(p-cymene)RuCl2]2. Nucleophilic addition of α-amino acid esters to the bis-chelate complexes M(oxophenyloxazolone)2(M = Ni, Cu) gave the dipeptide derivatives 13-18. Dinuclear Pd(II) and Pt(II) chelate complexes 19-23 were obtained from phenylene- and ethylenebridged bis(oxazolones). The structures of (Et3P)(Cl)Pd(O,N-oxophenyloxazolone) (6) and of Cl2(Et3P)Pt(2,2′-phenylene-bis(4-methyloxazolone)Pt(PEt3)Cl2 (20) were determined by X-ray diffraction. In complex 20 a close proximity of two phenylene H atoms to the metal is observed.
Axial Chirality in Square-Planar Metal Complexes
Authors: Enders Dieter , Gielen Heike , Breuer Klaus
Published: February 2015

Metal complexes with a square-planar arrangement of ligands are frequently found for the late Transition Metals. The incorporation of C1-symmetrical planar ligands (e.g. nucleophilic carbenes) in an orientation perpendicular to the square-plane of the complex leads to various isomers which are characterized by means of an axis of chirality employing the well established Cahn-Ingold-Prelog -R/S-nomenclature.
Aufbau von Nonaphen-und Dithianonaphen-Derivaten - Modellverbindungen für gewinkelte Bandstrukturen / Generation of Nonaphene and Dithianonaphene Derivatives - Model Compounds for Bent Molecular Ribbons
Authors: Meier Herbert , Rose Bernd
Published: February 2015

The cycloaddition of the bisdienophile 1 and the benzo[c]furan generated in situ from the precursor 2 yielded the nonaphene derivative 4 (Scheme 1). A related reaction (Scheme 3) was used for the preparation of the dithianonaphene systems 6a, b, c, namely the [2π+8π] cycloaddition of 1 and 2H-benzothiete (5/5′). Acidic dehydration (aromatization) of 6a, b, c led to the dithianonaphenes 7a, b, c (Scheme 4).
Notizen: Die Kristallstruktur von ClPb[N(SiMe3)2]3 / Crystal Structure of ClPb[N(SiMe3)2]3
Authors: Smith Donna M. , Neumüller Bernhard , Dehnicke Kurt
Published: February 2015

Pale brown single crystals of the title compound have been obtained by the reaction of Pb[N(SiMe3)2]2 with molybdenum pentachloride in ether solution as a result of a redox reaction. ClPb[N(SiMe3)2]3 crystallizes in the trigonal space group R3 with three formula units per unit cell. Lattice dimensions at -50 °C: a = b -1828.7(2), c = 854.5(1) pm. The compound forms monomeric molecules with bond lengths Pb-Cl = 247.9(4) pm and Pb - N = 213(2) pm.
Ubergangsmetall-substituierte Phosphane, Arsane und Stibane, LIX [1], Ein Addukt des Me3P-substituierten Ferrio-diphenylphosphans Cp(OC)(Me3P)Fe-PPh2 mit Methylisothiocyanat: Darstellung, Protonierung und Methylierung / Transition Metal Substituted Phosphanes, Arsanes and Stibanes, LIX [1]. An Adduct of the Me3P-Substituted Ferrio-diphenylphosphane Cp(OC)(Me3P)Fe-PPh2 and Methylisothiocyanate: Synthesis, Protonation, and Methylation
Authors: Malisch Wolfgang , Spörl Andre , Thirase Katharina , Fey Oliver
Published: February 2015

Treatment of the ferrio-phosphane Cp(OC)2Fe-PPh2 (1) with Me3P (2) yields Cp(OC)(Me3P)Fe-PPh2 (3) via CO-substitution. Reaction of 3 with methylisothiocyanate (4) leads to the formation of the adduct Cp(OC)(Me3P)Fe-PPh2 -C(S)NMe (5), which is regioselectively methylated at the sulfur atom with Mel (6a) or MeSO3CF3 (6b), respectively, to give the cationic complexes [Cp(OC)(Me3P)Fe-PPh2 -C(SMe)=NMe]I/CF3 SO3(7a,b). In contrast, protonation with CF3SO3H (8 ) occurs at the nitrogen atom, yielding [Cp(OC)(Me3P)Fe-PPh2- C(S)-N(H)Me]CF3SO3 (9). The structures of 7b and 9 have been determined by X-ray diffraction analysis
Phosphenium-Komplexe, 43 [1]. Ringöffnungsreaktionen der dreigliedrigen Phosphametallacyclen {PR2 = P(o-Tol)2, P(Ph)(o-Tol), P(Mes)[C(S)N(H)Et], P(/-Bu)[C(O)N(H)Et} / Phosphenium Complexes, 43 [1]. Ring-Opening Reactions of the Three-Membered Phosphametallacycles {PR1 = P(o-Tol)2, P(Ph)(oTol), P(Mes)[C(S)N(H)Et], P(r-Bu)[C(0)N(H)Et}
Authors: Malisch Wolfgang , El Baky Christa Abd , Grün Klaus
Published: February 2015

The three-membered phosphametallacycles

[R = o-Tol (3a), R = Ph(3b)] react with the tertiary phosphanes Me3P (4a), Me2PhP (4b) or MePh2P (4c) with ring opening and deselenation to the metallo-phosphanes fran.s-Cp(OC)2(R3P)WP(o-Tol)(R) (5a-d). Analogous reactions of the P-thioformamido- and formamido-substituted metallacycles

[R = Mes, X = S (6a); R = t-Bu, X = O (6b)] with Me3P (4a) yield in the case of 6a the tungsten-phosphane Cp(OC)2(Me3P)W-P(Mes)[C(S)N(H)Et] (7), while 6b affords the tungsten-selenophosphorane Cp(OC)2(Me3P)W-P(Se)(f-Bu)[C(0)N(H)Et] (8 ). Treatment of 7 with hydrogen chloride affords {Cp(OC)2(Me3P)W-P(H)(Mes)[C(S)N(H)Et] }C1 (9). With methyliodide, 8 is transformed into {Cp(OC)2(Me3P)W-P(SeMe)(t-Bu)[C(O)N(H)Et]}I (10)
Synthese, Kristallstruktur und Eigenschaften von Triguanidinium-tri--imidocyclotriphosphat-Monohydrat und Tetraguanidinium-tetra-/i-imidocyclotetraphosphat-Tetrahydrat, [C(NH2)3]3(PO2NH)3 · H2O und [C(NH2)3]4(PO2NH)4 · 4 H2O / Synthesis, Crystal Structure, and Properties of Triguanidinium Tri-/i-imidocyclotriphosphate Monohydrate and Tetraguanidinium Tetra-/i-imidocyclotetraphosphate Tetrahydrate, [C(NH2)3]3(PO2NH)3 · H2O and [C(NH2)3]4(PO*NH)4 · 4 H2O
Authors: Stock Norbert , Jürgens Barbara , Schnick Wolfgang
Published: February 2015

Coarsely crystalline [C(NH2)3]3(PO2NH)3 · H2O (1) and [C(NH2)3]4(PO2NH)4 · 4 H2O (2) have been obtained by addition of [C(NH2)3]2CO3 to a freshly prepared solution of H3(PO2NH)3 or to a suspension of H4(PO2NH)4 · 2 H2O , respectively, followed by diffusion controlled addition of acetone. The crystal structures of 1 and 2 have been determined by single crystal X-ray methods ([C(NH,)3]3(PO,NH)3 · H2O: Pbca; a = 1565.6(2), b = 1068.31(6), c = 2091.8(2) pm, Z = 8; [C(NH2)3]4(PO2NH)4 · 4 H2O: Pbcn; a = 1739.64(10), b = 1084.19(6), c = 1334.96(11) pm, Z = 4). The P3N3 and P4N4 rings of the anions exhibit the chair conformation. In 1 two cyclic anions are interconnected into pairs via hydrogen bonds. In 2 columns along [001] are formed by hydrogen bonds between the anions. Hydrogen bonding through water molecules and C(NH2)3
+ ions results in a three-dimensional network in 2. Complete dehydration is achieved below 160 or 180 °C for 1 or 2, respectively. Heating to 700 °C causes condensation reactions with evolution of NH3 and H2O yielding X-ray amorphous products
Niedere Hydrate aliphatischer primärer Amine. Neue Untersuchungen zu Bildung und Struktur [1] / Lower Hydrates of Aliphatic Primary Amines. New Studies of Formation and Structure [1]
Authors: Janeda Stephanie , Mootz Dietrich
Published: February 2015

After earlier work in this laboratory on lower hydrates of amines, the melting diagram of the system 1,8-diaminooctane/water and six new crystal structures of hemi- and monohydrates of terminal primary n-alkylamines and diamines have been determined. In the hydrates 1 -PrNH2 · 0.5 H2O (space group C 2/m with Z = 4 formula units per unit cell), l-HexNH2 · 0.5 H2O (PI, Z = 2) and H2N(CH2)nNH2 · H2O with n = 4, 6, 8 (P 2x/c, Z = 4), the O and N atoms are hydrogen-bonded into a two-dimensional array analogous to the mutual coordination of cations and anions in the Cdl2 structure type: [ON6/3] ~ [CdI6/3]. In the hydrate H2N(CH2)2NH2 · H2O (C 2/c, Z = 4), the H2O/NH2 partial structure is three-dimensional but can be reduced, by neglecting the longest H bond, to an array which is again just two-dimensional and related now to the red Hgl2 structure type: [ON4/2] ~ [HgI4/2], In all the monohydrates, the arrays as defined are crosslinked by the alkylene cnains of the bifunctional amine molecules
Synthesis and Thermal Properties of Twin Compounds, Alkanediacids 4-(4'-Cyano)-biphenyl Diesters
Authors: Białecka-Florjańczyk Ewa , Wolarz Eryk , Bauman Danuta
Published: February 2015

Alkanediacids 4-(4'-Cyano)-biphenyl Diesters, Twin M esogens Four twin mesogens from the hom ologous series of alkanediacids 4-(4'-cyano)-biphenyl diesters (n = 4, 6, 8, 10) have been synthesized and their thermal properties have been studied. Assignment of the phases has been made by means o f polarizing microscopy and DSC measurements. It has been found, that the increase of the spacer length causes the lowering of the mesophase temperature range and influences other thermodynamic parame­ ters of the compounds investigated.
Ab initio MO Optimizations of Osmiumtetracarbonyldihydride and Metallacyclophanes with two Osmium Atoms and their Molecular Complexes with Different Guests
Authors: Warttmann Inge , Häfelinger Günter
Published: February 2015

Ab initio Hartree-Fock (HF) and density functional (DFT) optimizations on the test m olecule osmiumtetracarbonyldihydride (13) with various basis sets show that the lanl2mb pseudopotential basis set for osmium leads in the HF approximation to more reliable molecular geometries than the DFT calculations. This HF procedure was used for the optimizations of molecular geometries of three isomeric 4,4,4,4,17,17,17,17-octacarbonyl-4,17-diosma[7.7]ortho-, meta- and paracyclophanes 1 to 3, of which 3 was found to be predestined for formation of various host-guest complexes with possible guests benzene (4), fluorobenzene (5), 1,3,5- trifluorobenzene (6), 1,2,4,5-tetrafluorobenzene (7), hexafluorobenzene (8), fluoroanil (9), tetrafluoroethene (10), tetracyanoethene (11) and aniline (12). Results of optimized hostguest geometries are presented graphically for inclusions and associations of guest 4 to 12 with 3. Calculated lanl2mb interaction energies, after correction for basis set superposition error (BSSE), remain favourable only for inclusion of 5 and associations of 5, 10, 11 and 12. Additionally lanl2dz single point calculations for inclusion, which may not need BSSE correction because of the improved basis set, are favourable for 6 and 12. According to lanl2mb HOMO and LUMO energies, 3 may as well easily donate or accept electrons. This may be an interpretation to the surprising effect, that Mulliken total charges are positive on the electron accepting guest molecules 4 to 11. There are geometrical peculiarities in the optimized host-guest complexes for inclusion and association. Fluorine atoms of 5 to 10 and nitrogen atoms of a cyano group of 11 and the amino group of 12 like to come close to one or two carbonyl groups. Similar distances of 2.70 Å to 3.57 Å between the O atom of the carbonyl group and the F atom or N atom appear in all optimizations of inclusion and association of 5 to 12 except in the case of association of tetrafluoroethene (10).
Kristallstruktur des Oxo-Acetatkomplexes [Co7(μ4- O)2(O2CCH3)10(OPEt3)2] / Crystal Structure of the Oxo-Acetate Complex [Co7(μ4 -O)2(O2CCH3)10(OPEt3)2]
Authors: Ackermann Hartmut , Leo Roland , Massa Werner , Dehnicke Kurt
Published: February 2015

Cobalt(II)acetate reacts with the silylated phosphinimine Me3SiNPEt3 at 230 °C to form a reaction mixture from which dark blue single crystals have been isolated by recrystallization from dichloromethane/ acetonitrile. They were identified by a crystal structure determination to be [Co7(μ4- O)2(O2CCH3)10(OPEt3)2] · 4 CH3CN (1). Lattice dimensions at 190 K: a = 1048.9(1), b = 1217.5(1), c = 1280.6(1) pm, a = 87.75(1)°, β = 77.72(1)°, y = 73.90(1)°, space group P1, Z = 1, R1 = 0.0257. 1 has a centrosymmetric cluster-like structure in which the central cobalt atom is connected via two μ4-oxygen atoms with the remaining six cobalt atoms to form a distorted Co(Co)6 octahedral skeleton. In addition, all cobalt atoms are linked by six ,μ2- O2CCH3
- groups and by four μ3-OC(O)CH3
- bridges
Gerüstumlagerungen bei einem Yliddiylphosphan-Tetrameren
Authors: Rearrangements Skeletal , Tetramer Ylidediylphosphane , Schrödel Hans-Peter , Schmidpeter Alfred , Nöth Heinrich
Published: February 2015

Condensation of the bis(trimethylsilyl)ylide Ph3PC(SiMe3)2 with PX3 (X = Cl, Br) yields the ionic tetramers 4a,b of ylidediyl-halophosphanes. Their cations (Ph3PC)4P4X3
+ possess a tetraphosphabicyclo[2.2.2]octane (or tetraphospha-barrelane) skeleton ([AC]3BD spin system in 31P NMR spectra). Reaction of 4a with AlCl3 or GaCl3 converts the singly charged cation into the tetracation (Ph3PC)4P4
4+ having a cubane structure ([AB]4 spin system in the 31P NMR spectum). SbCl5 oxidizes 4a to give the dication (Ph3PC)4P4Cl4
2+ (counter ion: SbCl5
2-) with the barrelane skeleton either preserved (7) or rearranged into a tetraphospha-bicylco[3.3.0]- octane structure 8. In the latter case the dication contains a central diphosphanedionium bridge. Replacement of a chloro-substituent in 4a by an amino group also gives rise to a further dissociation and a concomitant rearrangement. The resulting dications (Ph3PC)4P4NR2Cl2+ possess a tetraphospha-bicyclo-[3.2.1]octane structure (with eight nonequivalent phosphorus atoms).
Lewis Acid Catalyzed Z to E Isomerization of 1,2-Bis(diphenylphosphino) ethene
Authors: Sigl Marcus , Schier Annette , Schmidbaur Hubert
Published: February 2015

Z-1,2-Bis(diphenylphosphino)ethene, cis-Ph2PCH=CHPPh2, forms 1:2 adducts with GaBr3 and GaI3, the former of which has been identified in an X-ray diffraction study as the complex of the isomerized ligand, E-Ph2PCH=CHPPh2. The GaI3 complex is believed to be analogous on the basis of analytical and spectroscopic data. InBr3 affords a 1 :1 complex with an ionic structure [(Ph2PCH=CHPPh2)2lnBr2]+ [InBr4]- in which the cation contains the original cis-ligand. With Inl3 also a 1:1 adduct is obtained, where the metal triiodide unit is attached to only one phosphorus atom of the non-isomerized (cis) ligand in the solid state. There is rapid site exchange of the Inl3 unit in chloroform solution as followed by NMR spectroscopy. - The metal halide induced Z/E isomerization of Ph2PCH=CHPPh2 has been studied in various solvents and at variable temperature with stoichiometric and catalytic amounts of AIX3 and GaX3 Lewis-acids. InX3 compounds proved ineffective (X = Cl, Br, I). Anhydrous AlBr3 was found to be most efficient, giving a 90% Z/E conversion in 10 min at 100°C in toluene. A mechanism is proposed which is compatible with the experimental data.
Kristallstrukturen, Schwingungsspektren und Normalkoordinatenanalyse von cis-[ReCl4X2]2-, X = NCS, NCSe / Crystal Structures, Vibrational Spectra and Normal Coordinate Analysis of cis-[ReCl4X2]2-, X = NCS, NCSe
Authors: Homolya L. , Strueß S. , Preetz W.
Published: February 2015

The crystal structures of cis-(n-Bu4N)2[ReCl4(NCS)2] (triclinic, space group P1̅, a = 11,245( 1), b = 20.174(3), c = 21.320(8) Å, a =109.06(2), β = 96.46(2), γ = 98.22(5)°, Z = 4) and cis-(Ph4P)2[ReCl4(NCSe)2]·2CH2Cl2 (triclinic, space group P1̅, a = 10.341(2), b = 13.436(3), c = 19.616(4) Å, α = 92.70(2), β = 92.02(2), γ = 89.99( 1)°, Z= 2) have been determined by single crystal X-ray diffraction analysis. Both ambidentate ligands NCS and NCSe are bonded via the N atom. Using the molecular parameters of the X-ray determinations the low temperature (10 K) IR and Raman spectra of the (n-Bu4N) salts have been assigned by normal coordinate analysis based on a modified valence force field. The valence force constants fd(ReN) are 1,78(NCS) and 1,79(NCSe) mdyn/ Å.
Thermochemisches und kalorisches Verhalten von NdAl3Cl12 / Thermochemical and Calorical Behaviour of NdAl3Cl12
Authors: Oppermann H. , Zhang M. , Hennig C.
Published: February 2015

The thermodynamical data of solid and gaseous aluminium neodymium chloride have been obtained by determination of the decomposition equilibria (of solid) from total pressure measurements and chemical transport reactions (gaseous). The melting diagram was determined by DTA. The enthalpy of formation of the solid phase was calculated from their heats of solution and from the enthalpies of formation and the heats of solution of NdCl3 and AlCl3.

Data by total pressure measurement:

ΔH°B |(NdAl3Cl12,f,298) = -749,6 ± 2,5 kcal/mol; S°(NdAl3Cl12,f,298) = 118,2 ± 3,0 cal/K·mol.

Data by solution calorimetry: ΔH°B(NdAl3Cl12,f,298) = -748,6 ± 1,3 kcal/mol.

Data by chemical transport:

ΔH°B(NdAl3Cl12,g,298) = -701,5 ± 3,0 kcal/mol; S°(NdAl3Cl12,g,298) = 215,0 ± 4,0 cal/K-mol.
Oligomere Tetraeder-Anionen in Borophosphaten: Sechserringe mit offenen und cyclischen Phosphat-Verzweigungen in der Kristallstruktur von K6Cu2[B4P8O28(OH)6] / Oligomeric Tetrahedral Anions in Borophosphates: Six-Membered Rings with Open and Cyclic Phosphate Branchings in the Crystal Structure of K6Cu2[B4P8O28(OH)6]
Authors: Boy Insan , Cordier Gerhard , Kniep Rüdiger
Published: February 2015

Crystals of K6Cu2[B4PhO28(OH)6] were grown under hydrothermal conditions at 160 °C. The crystal structure (monochnic, P21/c (Nr. 14), a = 961.8(1), b = 1755.0(1), c = 942.0(1) pm, β = 112.29(1)°, Z = 2) contains oligomeric tetrahedral anions based on six-membered rings {B4P2O10O8/2} with additional branchings by hydrogenphosphate-groups (open branching: 4 x HPO3O1/2; cyclic branching: 2 x HPO2O2/2). The complex borophosphate anion is represented by the formula [B4P8O28(OH)6]10-. Cu2+ is in a tetragonal pyramidal and K+ in an irregular coordination by eight and nine oxygen ligands, respectively.
Übergangsmetallkomplexe mit Schwefelliganden, CXXXIII [1]. Synthese, Struktur und Eigenschaften neuer FeII-Komplexe mit [FeN2S2]-Gerüsten / Transition Metal Complexes with Sulfur Ligands, CXXXIII [1]. Synthesis, Structure, and Properties of New FeII Complexes with [Fe2N2S2] Cores
Authors: Sellmann Dieter , Emig Susanne , Heinemann Frank W. , Knoch Falk
Published: February 2015

In order to obtain suitable precursors for iron complexes that model the reactivity of the active sites of nitrogenases, the coordination chemistry of the [Fe(′N2H2S2′)] fragment was systematically investigated(′N2H2S2′2- = 1,2-ethanediamine-N,N′-bis(2-benzenethiolate)(2-)). One-pot reactions of FeCl2 -4H2O with the tetradentate amine-thiolate ligand ′N2H2S2′2- and CO, PR3 or P(OR)3 yielded the complexes [Fe(CO)2(′N2H2S2′)] (1), [Fe(CO)(PR3)(′N2H2S2′)] (R = Et (2), Pr (3), Bu (4)), [Fe(PMe3)2 (′N2H2S2′)] (7), [Fe(dppe)(′N2H2S2′)] (8 , dppe = 1,2- bis(diphenylphosphine)ethane), and [Fe(P(ÖR)3)2(′N2H2S2′)l (R = Me (9), Pr (10)). Mixed phosphane/phosphite complexes [Fe(PMe3)(P(OR)3)(′N2H2S2′)] (R = Me (11), Pr (12)) were synthesized by PMe3/P(OPr)3 exchange of the labile complexes [Fe(PMe3 )2(′N2H2S2′)] (7) and [Fe(P(OPr)3)2(′N2H2S2′)] (10). The [Fe(CO)(PR3)(′N2H2S2′)l complexes 3 and 4 also resulted from 1 and PR3 by photochemical CO substitution. They exhibit characteristic low-frequency v (CO) bands ( ≈1925 cm-1), and their remaining CO ligand proved photolytically inert. Reaction of 3 or 4 with NOBF4 yielded the dinuclear NO complex [Fe(NO)(′N2HS2′)]2 (6 ) which contains two amide functions.

Contrary to expectations, [Fe(PR3)2(′N2H2S2′)l complexes could not be obtained with monodentate phosphanes other than PMe3. The corresponding N-methylated ligand ′N2Me2S2,2- yielded only the complexes [Fe(CO)2 (′N2Me2S2′)] (15) and [Fe(′N2Me2S2′)] (16). X-ray structure analyses of complexes 7, 8 -MeOH, 3, [Fe(CO)(dppm)(′N2H2S2 ′)]·0,5 THF (5 ·0,5THF, dppm = bis(diphenylphosphino)methane), and 12·0,5′N2 H2S2 ′-H2 confirm the pseudo-octahedral coordination of the Fe centers by two trans-S and two cis-N donors and two c/s-coligands. The structural data further suggest that the unexpected instability of the [Fe(PR3)2 (′N1H2S2′)] complexes is not caused by steric but by electronic effects. The cyclic voltammograms and the reactivity of the [Fe(L)(L′)(′N2H2S2′)] complexes corroborate this assumption. The oxidation behaviour of the [Fe(L)(L′)(′N2H2S2′)] complexes depends critically on the coligands L and L′. Reaction of 1 with dioxygen leads to oxidative dehydrogenation of the ′N2H2S2′2- ligand and yields the dinuclear Schiff-Base complex [Fe(′gma′ )]2 (′gma′2- = glyoxal-bis(2- mercaptoanil)(2-)). In contrast, oxidation of [Fe(CO)(PR3)(′N2H2S2′)], [Fe(PR3)2 (′N2H2S2′)] and [Fe(P(OR)3)2 (′N2H2S2)] complexes by dioxygen occurs metal-centered and gives the Fe(IV) complexes [Fe(PR3)(′N2S2′)] (R = Me, Pr), [Fe(P(OR)3)(′N2S2′)] (R = Me) and [Fe(′N2S2′)]2 that contain the tetraanionic thiolate-amide ligand ′N2S2′4-.
BaCu6Ge2S8 -Ein Thiogermanat als Variante der Li3Bi-Struktur / BaCu6Ge2S8 -A Thiogermanate as a Variant of the Li3Bi Structure
Authors: Tampier Markus , Johrendt Dirk
Published: February 2015

BaCu6Ge2 S8 was synthesized by direct reaction of the elements at 750°C and characterized by X-ray single crystal techniques. The thiogermanate crystallizes in a new orthorhombic structure type (a = 6.122(1) Å, b = 12.084(3) Å, c = 17.614(5) Å; Pbcm, Z = 4). Isolated [GeS4]4- tetrahedra form a slightly distorted cubic face-centered (fee) arrangement. Baand Cu-atoms each occupy half the octahedral gaps (OG) of this “tetrahedra packing” . Further Cu atoms fill the tetrahedral gaps ( TG) completely. The compound can be written as Ba2
(1/2OG)(Cu2)2
(1/2OG)Cu8
(TG)(GeS4)4 . Thus the structure of BaCu6Ge2S8 can be derived from the Li3Bi type. The sulfur coordination of the metal atoms (Cu tetrahedral or trigonal, Ba with CN 8) are realized by the spatial orientation of the [GeS4]4- tetrahedra. Their centers nearly maintain the fcc-arrangement. This structure interpretation of BaCu6 Ge2S8 from the viewpoint of a “filled tetrahedra packing” is discussed for further known thiogermanate compounds.
Molecular Recognition Analyzed by Observing Intramolecular Interconversion with EPR Spectroscopy
Authors: Jäger Martin , Schuler Paul , Stegmann Hartmut B. , Rockenbauer Antal
Published: February 2015

Molecular recognition between Rebek’s cleft R and 4-(2-benzimidazolyl)-aminomethyl-2,6-di-rm-butyl-phenol (Bi) is investigated by means of EPR spectroscopy. Their specific inter-molecular interactions are distinguished from non-specific interactions represented by mere protonation on addition of benzoic acid. Both interactions are related to intramolecular in­ terconversions at the C∞-atom of Bi*, where a two-jump mechanism is found for free and protonated Bi* and a two-site exchange for the complexed ligand. While NMR spectroscopy indicates the existence of 1:1 and 1:2 receptor-substrate complexes, the faster time scale of EPR spectroscopy allows to identify one 1 : 2 as well as three 1 : 1 associates and to elucidate their formation conditions. Based upon the corresponding hf parameters, binding modes and sites are proposed for the key-in-the-lock system.
Darstellung und Strukturbeschreibung von NaCa3 Mn(V2O7)(V3O10) / Preparation and Structure of NaCa3Mn(V2O7)(V3O10)
Authors: Rettich R. , Müller-Buschbaum Hk.
Published: February 2015

Single crystals of NaCa3 Mn(V2O7)(V3O10) have been prepared by crystallization from flux in argon atmosphere. X-Ray single crystal methods led to triclinic symmetry, space group C1
i - P 1̄, a = 6.8798(9), b = 6.902(1), c = 15.480(2) Å, α = 87.39(1), β = 85.32(1), γ = 86.25(2) °, Z = 2. The compound belongs to the rare trivanadates showing V2O7 and V3O10 groups incorporated into a NaCaMn/O framework. One point position of the cations is occupied by Ca2+, three by Na+ and Ca2+ in a statistical distribution and a fourth one by Mn2+. The surrounding of Mn2+ and the statistically occupied position M(3) are octahedra, the other metal positions are centers of capped trigonal prisms.
Ba4Mn2Ag2O(As04)4 , ein Barium-Mangan-Oxid-Arsenat mit nichtlinearen O-Ag-O-Hanteln / Ba4Mn2Ag2O(AsO4)4, a Barium Manganese Oxide-Arsenate Showing Nonlinear O-Ag-O Dumbbells
Authors: Staack M. , Müller-Buschbaum Hk.
Published: February 2015

Single crystals of Ba4Mn2Ag2O(AsO4)4 have been prepared by solid state reactions using metallic silver as reactant. X-ray techniques led to monoclinic symmetry, space group D2h-P2,/m, a = 8.739(2), b = 5.912(1), c = 9.440(2) Å, β = 115.21(1)°, Z = 1. The crystal structure is characterized by O-Ag-O dumbbells, bond angle = 165,3°, containing one oxygen atom not associated with the arsenate groups. Considering these facts Ba4Mn2Ag2O(AsO4)4 may be seen as an oxide-arsenate or an oxoargentate(I)-arsenate. Assuming the oxidation state +II for manganese, as confirmed by magnetic measurements, the compound has an oxygen deficite which was accounted for by a split position model.
Hydrido(acylphenolato)cobaIt(III)-Verbindungen mit Trimethylphosphan-Liganden / Hydrido(acylphenolato)cobalt(III) Compounds Containing Trimethylphosphane Ligands
Authors: Klein Hans-Friedrich , Haller Stefan , Sun Hongjian , Li Xiaoyan , Jung Thomas , Röhr Caroline , Flörke Ulrich , Haupt Hans-Jürgen
Published: February 2015

Salicylaldehyde derivatives and related β-hydroxo aldehydes CHO-CR=CR′-OH react with CoMe(PMe3)4 via oxidative substitution to form low-spin d6 complexes mer-CoH(CO-CR=CR-O)(PMe3)3. Reductive elimination of acyl and hydride functions from cis positions at the metal is less favourable than in carbonyl cobalt intermediates through a pronounced stabilization by neutral phosphane σ-donor and dianionic acylenolato chelate ligands. Reactions of the hydride complexes with iodomethane or with protic acids HX afford octahedral molecular complexes mer-CoX(CO-CR=CR′-O)(PMe3)3 (X =I, OAc) and mer-CoX(CO-CR=CR′-O)(PMe3)2 (X = OAc, O-CR′=CR-CHO) without opening of the acylenolato chelate ring.
Weitere Verbindungen zum Ba6Nd2Al4O15-Typ: Ba4Nd4Zn3PtO15 und Ba4Eu4Zn3PtO15 / Further Compounds of the Ba6Nd2Al4O15 Type: Ba4Nd4Zn3PtO15 and Ba4Eu4Zn3PtO15
Authors: Sfreddo O. , Muller-Buschbaum Hk.
Published: February 2015

The compounds Ba4Nd4Zn3PtO15; (I) and Ba4Eu4Zn3PtO15 (II) crystallize with hexagonal symmetry, space group C4
6V-P63mc, (I): a = 11.719(1), c = 6.778(1) Å, (II): a = 11.654(1), c = 6.778(1) Å, Z = 2. Both belong to the Ba6Nd2-. AI4O15 type when replacing 2Ba2+ by 2Ln3+ and 4Al3+ by 3Zn2+ + Pt4+. The tetrahedrally coordinated Al3+ is substituted by Zn2+, the octahedrally one by Pt4+. Due to the similarity of X-ray scattering of Ba2+ and Ln3+ the ordered replacement of Ba2+ by Ln3+ has been proven by calculations of the Coulomb terms of lattice energy.
Development of a Program-Loading Spectrum for the Accelerated Durability Test of Lower Control Arm
Authors: Yu Jiawei , Zheng Songlin , Liang Guoqing , Feng Jinzhi
Published: February 2015

This study aims to develop a program-loading spectrum for the accelerated durability test of automotive components, with the lower control arm of a suspension as an example. Spectrum development is divided into three parts, namely, load spectrum acquisition, spectrum preprocessing, and program-loading spectrum development. Based on the strengthening property of structural low-amplitude loads under constant and random loadings, a program-loading spectrum-development method considering the strengthening effect of low-amplitude loads (SLAL) below the fatigue limit is proposed. Meanwhile, an equivalent strengthening methodology is considered during spectrum development. The number of loading cycles is decreased, and the bench test time is notably reduced by adjusting strengthening loads to the most effective level. The bench test proved that the influence of SLAL during spectrum development can simulate actual load conditions more effectively and precisely. Thus, this method can accurately predict fatigue failure from the durability test and can efficiently reduce durability test time.
Loss of Cyclin-Dependent Kinase 5 from Parvalbumin Interneurons Leads to Hyperinhibition, Decreased Anxiety, and Memory Impairment
Authors: Rudenko Andrii , Seo Jinsoo , Hu Ji , Su Susan C. , de Anda Froylan Calderon , Durak Omer , Ericsson Maria , Carlén Marie , Tsai Li-Huei
Published: February 2015

Perturbations in fast-spiking parvalbumin (PV) interneurons are hypothesized to be a major component of various neuropsychiatric disorders; however, the mechanisms regulating PV interneurons remain mostly unknown. Recently, cyclin-dependent kinase 5 (Cdk5) has been shown to function as a major regulator of synaptic plasticity. Here, we demonstrate that genetic ablation of Cdk5 in PV interneurons in mouse brain leads to an increase in GABAergic neurotransmission and impaired synaptic plasticity.PVCre;fCdk5mice display a range of behavioral abnormalities, including decreased anxiety and memory impairment. Our results reveal a central role of Cdk5 expressed in PV interneurons in gating inhibitory neurotransmission and underscore the importance of such regulation during behavioral tasks. Our findings suggest that Cdk5 can be considered a promising therapeutic target in a variety of conditions attributed to inhibitory interneuronal dysfunction, such as epilepsy, anxiety disorders, and schizophrenia.
Sensory Deprivation Disrupts Homeostatic Regeneration of Newly Generated Olfactory Sensory Neurons after Injury in Adult Mice
Authors: Kikuta Shu , Sakamoto Takashi , Nagayama Shin , Kanaya Kaori , Kinoshita Makoto , Kondo Kenji , Tsunoda Koichi , Mori Kensaku , Yamasoba Tatsuya
Published: February 2015

Although it is well known that injury induces the generation of a substantial number of new olfactory sensory neurons (OSNs) in the adult olfactory epithelium (OE), it is not well understood whether olfactory sensory input influences the survival and maturation of these injury-induced OSNs in adults. Here, we investigated whether olfactory sensory deprivation affected the dynamic incorporation of newly generated OSNs 3, 7, 14, and 28 d after injury in adult mice. Mice were unilaterally deprived of olfactory sensory input by inserting a silicone tube into their nostrils. Methimazole, an olfactotoxic drug, was also injected intraperitoneally to bilaterally ablate OSNs. The OE was restored to its preinjury condition with new OSNs by day 28. No significant differences in the numbers of olfactory marker protein-positive mature OSNs or apoptotic OSNs were observed between the deprived and nondeprived sides 0–7 d after injury. However, between days 7 and 28, the sensory-deprived side showed markedly fewer OSNs and mature OSNs, but more apoptotic OSNs, than the nondeprived side. Intrinsic functional imaging of the dorsal surface of the olfactory bulb at day 28 revealed that responses to odor stimulation were weaker in the deprived side compared with those in the nondeprived side. Furthermore, prevention of cell death in new neurons 7–14 d after injury promoted the recovery of the OE. These results indicate that, in the adult OE, sensory deprivation disrupts compensatory OSN regeneration after injury and that newly generated OSNs have a critical time window for sensory-input-dependent survival 7–14 d after injury.
The Roles of Cdk5-Mediated Subcellular Localization of FOXO1 in Neuronal Death
Authors: Zhou Jiechao , Li Huifang , Li Xiaoping , Zhang Guanyun , Niu Yaqiong , Yuan Zengqiang , Herrup Karl , Zhang Yun-Wu , Bu Guojun , Xu Huaxi , Zhang Jie
Published: February 2015

Deficiency of cyclin-dependent kinase 5 (Cdk5) has been linked to the death of postmitotic cortical neurons during brain development. We now report that, in mouse cortical neurons, Cdk5 is capable of phosphorylating the transcription factor FOXO1 at Ser249in vitroandin vivo. Cellular stresses resulting from extracellular stimulation by H2O2or β-amyloid promote hyperactivation of Cdk5, FOXO1 nuclear export and inhibition of its downstream transcriptional activity. In contrast, a loss of Cdk5 leads to FOXO1 translocation into the nucleus: a shift due to decreased AKT activity but independent of S249 phosphorylation. Nuclear FOXO1 upregulates transcription of the proapoptotic gene,BIM, leading to neuronal death, which can be rescued when endogenous FOXO1 was replaced by the cytoplasmically localized form of FOXO1, FOXO1-S249D. Cytoplasmic, but not nuclear, Cdk5 attenuates neuronal death by inhibiting FOXO1 transcriptional activity and BIM expression. Together, our findings suggest that Cdk5 plays a novel and unexpected role in the degeneration of postmitotic neurons through modulation of the cellular location of FOXO1, which constitutes an alternative pathway through which Cdk5 deficiency leads to neuronal death.
Cooperative Roles of Hydrophilic Loop 1 and the C-Terminus of Presenilin 1 in the Substrate-Gating Mechanism of γ-Secretase
Authors: Takagi-Niidome Shizuka , Sasaki Tomoki , Osawa Satoko , Sato Takeshi , Morishima Kanan , Cai Tetsuo , Iwatsubo Takeshi , Tomita Taisuke
Published: February 2015

γ-Secretase is a multisubunit protease complex that is responsible for generating amyloid-β peptides, which are associated with Alzheimer disease. The catalytic subunit of γ-secretase is presenilin 1 (PS1), which contains an initial substrate-binding site that is distinct from the catalytic site. Processive cleavage is suggested in the intramembrane-cleaving mechanism of γ-secretase. However, it largely remains unknown as to how γ-secretase recognizes its substrate during proteolysis. Here, we identified that the α-helical structural region of hydrophilic loop 1 (HL1) and the C-terminal region of human PS1 are distinct substrate-binding sites. Mutational analyses revealed that substrate binding to the HL1 region is critical for both ε- and γ-cleavage, whereas binding to the C-terminal region hampers γ-cleavage. Moreover, we propose that substrate binding triggers conformational changes in PS1, rendering it suitable for catalysis. Our data provide new insights into the complicated catalytic mechanism of PS1.
The Nucleus Prepositus Hypoglossi Contributes to Head Direction Cell Stability in Rats
Authors: Butler William N. , Taube Jeffrey S.
Published: February 2015

Head direction (HD) cells in the rat limbic system fire according to the animal's orientation independently of the animal's environmental location or behavior. These HD cells receive strong inputs from the vestibular system, among other areas, as evidenced by disruption of their directional firing after lesions or inactivation of vestibular inputs. Two brainstem nuclei, the supragenual nucleus (SGN) and nucleus prepositus hypoglossi (NPH), are known to project to the HD network and are thought to be possible relays of vestibular information. Previous work has shown that lesioning the SGN leads to a loss of spatial tuning in downstream HD cells, but the NPH has historically been defined as an oculomotor nuclei and therefore its role in contributing to the HD signal is less clear. Here, we investigated this role by recording HD cells in the anterior thalamus after either neurotoxic or electrolytic lesions of the NPH. There was a total loss of direction-specific firing in anterodorsal thalamus cells in animals with complete NPH lesions. However, many cells were identified that fired in bursts unrelated to the animals' directional heading and were similar to cells seen in previous studies that damaged vestibular-associated areas. Some animals with significant but incomplete lesions of the NPH had HD cells that were stable under normal conditions, but were unstable under conditions designed to minimize the use of external cues. These results support the hypothesis that the NPH, beyond its traditional oculomotor function, plays a critical role in conveying vestibular-related information to the HD circuit.
Adult Cortical Plasticity Studied with Chronically Implanted Electrode Arrays
Authors: Abe Hiroshi , McManus Justin N.J. , Ramalingam Nirmala , Li Wu , Marik Sally A. , Meyer zum Alten Borgloh Stephan , Gilbert Charles D.
Published: February 2015

The functional architecture of adult cerebral cortex retains a capacity for experience-dependent change. This is seen after focal binocular lesions as rapid changes in receptive field (RF) of the lesion projection zone (LPZ) in the primary visual cortex (V1). To study the dynamics of the circuitry underlying these changes longitudinally, we implanted microelectrode arrays in macaque (Macaca mulatta) V1, eliminating the possibility of sampling bias, which was a concern in previous studies. With this method, we observed a rapid initial recovery in the LPZ and, during the following weeks, 63–89% of the sites in the LPZ showed recovery of visual responses with significant position tuning. The RFs shifted ∼3° away from the scotoma. In the absence of a lesion, visual stimulation surrounding an artificial scotoma did not elicit visual responses, suggesting that the postlesion RF shifts resulted from cortical reorganization. Interestingly, although both spikes and LFPs gave consistent prelesion position tuning, only spikes reflected the postlesion remapping.