bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the free energy of transfer of electrolytes, measured with cells without transference, with the sum of the free energies of the corresponding cations and anions with the Owen-cell on standard conditions
Authors: Schwabe K , Hoffmann W , Queck C
Published: September 2010

The comparison of S2ΔS1G°tr(E1) with the sum of the values for the corresponding cation and anion
S2ΔS1G°tr(Ct+)~S2ΔS1G°tr(X-) (measured) with Owen cells, gained by double extrapolation and by
the assumption that the liquid junction potential at 1→0 may be neglected) gives values which differ
by not more than ±5%. Most of the investigated acids allow the conclusion that the pH values,
measured in cells with transference, and having the same electrodes, give good information on the
acidity of the organic solvent and its water mixtures, referred to the standard state in water. That
means that the pH, changed to the same H+ concentration in the solvent compared with that in
water, is essentially an effect of the free energy of transfer of the hydrogen ion and not of very high
liquid junction potentials.
Cyclopentadienyl-ruthenium and -osmium chemistry. XXII. Synthesis, X-ray structure and some reactions of RuCl(PPh3,)(η1-dppm)(η-C5H5),containing a monodentate CH2(PPh2)2 ligand
Authors: Bruce MI , Humphrey MG , Patrick JM , White AH
Published: September 2010

.Stoichiometric amounts of RuCl(PPh3)2(η-C5H5) and dppm react in refluxing C6H6 to give RuCl-
(PPh3)(η1-dppm)(η-C5H5) which has been fully characterized by an X-ray study (triclinic, space
group P1, a 22.377(6), b 9.913(2), c 9.826(3)Ǻ, α 70.46(2), β 78.72(2), γ 80.40(2)°, Z 2) in which
3299 data [I > 3σ(I)] were refined to R 0.046, R' 0.052. Structural parameters are similar to those
of other RuX(PR3)2(η-C5H5) complexes. The chloro complex was converted into [Ru(PPh3)(η2-
dppm)(η-C5H5)]+ salts; the other PPh3 ligand can be replaced by a second dppm ligand to give
[Ru(dppm)2(q-C5H3)+ which contains both mono- and bidentate dppm ligands. Alkylation of
the uncoordinated phosphorus with MeI is accompanied by halogen exchange to give [RuI(PPh3)-
(PPh2CH2PMePh2)(η-C5H5)I], while reactions with a variety of transition metal complexes result
in abstraction of PPh3 and formation of RuCl(dppm)(η-C5H5).
Metal complexes of dicamba: the crystal and molecular structures of dicamba(3,6-Dichloro-2-methoxybenzoic acid) and catena-μ-Aqua-diaquabis(3,6-dichloro-2-methoxybenzoato)zinc(II) dihydrate
Authors: Smith G , O'Reilly EJ , Kennard CHL
Published: September 2010

The crystal structures of
the herbicide, dicamba (3,6-dichloro-2-methoxybenzoic
acid) and the zinc(II) complex of this acid, {[Zn(dicamba)2(H2O)3].2H2O}}n
(1), have been determined from X-ray diffraction data and refined by least
squares to final residuals of 0.034 and 0.043 respectively. Dicamba
is triclinic, space group P1, Z 2 with a cell a 7.232(1), b 7.971(1), c 9.050(3) �, α 102.76(3), β
91.33(3), γ 110.38(1)�, while (1) is monoclinic, space group P21/n,
Z 4 with a cell a 10.467(1), b 8.135(3), c 28.079(2) �, β 96.497(7)�. Dicamba
forms hydrogen-bonded cyclic dimers [O---O, 2.655(7) �]
with the carboxyl and the methoxy groups synclinal to the benzene ring. The dicamba ligands retain their conformation in the ZnII
complex and are cis-related and unidentate [Zn-0,2.083,2.095(4) �]. Three of the waters are
coordinated [Zn-0, 2.036, 2.055, 2.099(4) �] with one of these also acting as a
bridging ligand between the octahedral zinc centres
[Zn-0, 2.326(4) �], giving a 'linear' polymer structure [Zn-0-Zn bridge angle,
133.6(3)�]. The MnII and CoII complexes of dicamba [(2) and (3)] have been confirmed as isomorphous and isostructural
with the ZnII analogue.
Chemistry of kojic acid: One-step syntheses of benzothiazoles and other fused heterocycles from kojic acid derivatives
Authors: Teitei T
Published: September 2010

The reactions of the benzyl
ether (1b) of kojic acid (la) and its chloromethyl derivative (1c) were investigated as new
routes to fused heterocyclic systems. The chloromethyl
compound proved the more versatile intermediate yielding benzothiazoles
with thiourea and pyrido[l,2-a]benzimidazoles
(11) and pyrido[1,2-alindole (12b) with pyridine derivatives. A number of
methylated products of the benzothiazole were
prepared in order to establish the structures of the reaction products and a
possible mechanism of the reaction is discussed.
Ruthenium and iron complexes of dipicolinic acid: Synthesis, solution properties and kinetics of electron transfer reactions with ascorbate ions
Authors: Williams NH , Yandell JK
Published: September 2010

Standard potentials of the
redox couples [bis(pyridine-2,6-dicarboxylate)MIII]-/2-
([M(dipic)2]-/2-, where M = Fe,
Ru, Co) have been determined at 25�C, and ionic
strength 0.1M (NaClO4 or KNO3). Kinetics of reduction of
the oxidized complexes by ascorbate have also been
examined under the same conditions. The [Fe(dipic)2]-/2-
potential was found to be 355 � 5 mV. Reduction of [Fe(Fe(dipic)2]-
in the pH range 4-6 was shown to occur by reaction with ascorbate
monoanion (HA-) with a rate constant of (2.2 � 0.2) × 103
1. mol-1 s-1, and ascorbate dianion(A2-) with a rate constant of (7 � 1) × 108
1. mol-1 s-1. K [Ru(dipic)2] has been synthesized. Spectroscopic and
analytical evidence suggest that it is a simple six-coordinate species in the
solid and in non-aqueous solvents, but that in water it exists as an
equilibrium mixture of at least two species. The redox potential for this
mixture was found to be 270 � 10 mV. The major component of this mixture is
reduced by A2- with a rate constant of (4.7 � 0.1) × 1081.mol-1
s-1. A value of 747 � 5 mV was measured for the redox potential of
the cobalt couple, although equilibration of this system with the inert
electrode could be achieved only by using [Fe(bpy)2(CN)2]
as a mediator. Kinetics of reduction of [Co(dipic)2]-
by ascorbate were complex and not reproducible.
Synthesis of a model phosphopeptide
Authors: Alewood PF , Palma S , Johns RB
Published: September 2010

The model phosphopeptide N-acetyl-O-phosphonoserine
methylamide was synthesized in five steps.
The chemistry of Eremophila spp. XXI. Structural study of a new eremane diterpene
Authors: Croft KD , Ghisalberti EL , Jefferies PR , Mori TA , Skelton BW , White AH
Published: September 2010

The structure of a new eremane diterpene isolated from Eremophila cuneifolia
Kraenzlin has been determined by X-ray
crystallographic methods. The conversion of this diterpene
into sesquiterpeneswith the same tricyclic
skeleton is described.
Improved Richman-Atkins syntheses of cyclic polyamines particularly 1,4,7-Triazacyclononane (tacn) and 1,4,7-Triazacyclodecane (tacd), with the aid of cation-exchange in purification and isolation
Authors: Searle GH , Geue RJ
Published: September 2010

Richman-Atkins cyclization
syntheses for the cyclic triamines 1,4,7-triazacyclononane (tacn) and
1,4,7-triazacyclodecane (tacd) with the alternative possible sets of reagents
as tosyl derivatives have been examined in detail and compared. The cyclizations
from the tritosyl derivative of diethylenetriamine (dientt) and the appropriate
diols as ditosylates proceeded relatively cleanly, although there were small
amounts of higher products and some carry through of dientt for tacn. The
alternative cyclizations, from 2,2'-(tosy1imino)bisethyl ditosylate and a
ditosyl diamine, gave little reaction to form tacn as the tritosyl derivative.
The reaction to form tritosyl tacd proceeded further, but was accompanied by
significant formation of higher condensation products, particularly the
hexamines 1,4,7,11,14,17-hexaazacycloeicosane (2 : 2 cyclic dimer) and
3,7,10,13-tetraazahexade- cane-1,16-diamine. A cation-exchange procedure,
applied after the detosylation stage, is described for obtaining the required
pure 1 : 1 cyclic polyamines as their hydrochloride salts with high recovery.
This is an effective method for removing higher co-products. These may be
recovered, and by this means the above hexamines were isolated in admixture.
Heterocyclic amplifiers of phleomycin. II. Thiazol-4'-ylpyrazines with phenyl substituents and strongly basic side chains
Authors: Barlin GB
Published: September 2010

The preparation of a series
of 2'-substituted 2-(thiazol-4'-1)pyrazines by ring closure of
chloro-methylpyrazin-2-yl (and 3-,5- and 6-phenylpyrazin-2-yl) ketones with
ammonium dithiocarbamate, methyl dithiocarbamate and N-methylthiourea are
described. Mercapto compounds were converted into dimethylaminoalkyl(thio)
derivatives. As amplifiers of phleomycin, N,N-dimethyl-3-[4'-
(pyrazin-2-yl)thiazol-2'-ylthio]propylamne and
N,N-dimethyl-2-[4'-(3''-phenylpyrazin-2''-yl)thiazol-2'-yl]thioethylamine
showed three star activity.
Halogenated terpenoids. XXI. Concerning endo-2-Chloro-2,3,3-trimethylbicyclo-[2.2.1]heptane (endo-2-Chloro-2,3,3-trimethylnorbornane : endo-3-Chlorocamphane)
Authors: Brecknell DJ , Carman RM , Greenfield KL
Published: September 2010

The stability of the title
compound is discussed and attempts to synthesize it are described.
The chemistry of aryllead(IV) tricarboxylates. Reaction with derivatives of malonic acid: New routes to α-aryl carboxylic acids and arylated barbituric acid derivatives
Authors: Kopinski RP , Pinhey JT , Rowe BA
Published: September 2010

Derivatives of
2,2-dimethyl-1,3-dioxan-4,6-dione (Meldrum's acid) and the sodium salts of
substituted malonic esters undergo electrophilic C-arylation in high yield with
aryllead triacetates, thus providingnew routes to α-arylalkanoic
acids. Syntheses of the antiflammatory compound 2-(p-isobutylphenyl)-propanoic
acid (Ibuprofen) have been carried out to demonstrate the method. The arylation
reactionhas been extended to
5-ethylbarbituric acid and to barbituric acid itself, which affords the
5,5-diarylated derivatives in good yield. A study of the effect of some
tertiary bases on there action of p-methoxyphenyllead triacetate with the
5-isopropyl derivative of Meldrum's acid has shown that replacement of pyridine
by 2,2'-bipyridyl results in an increase in yield and reaction rate, while a
further marked improvement occurs in the presence of 1,10-phenanthroline.
Stark effect measurements of molecular dipole moments
Authors: Brown RD , Godfry PD
Published: September 2010

Attention is drawn to the
advantage of using certain selected a-type
transitions of near-symmetric prolate asymmetric tops
for precise determination of �b or �c in such molecules.
For two such molecules, propynal and
(E)-crotonaldehyde, new values of �b have been determined (Cm):
propynal �b
= 4.897(50) × 10-30 (E)-crotonaldehyde �b = 3.403(59) × 10-30
which are substantially
different from those previously published. Some other uses of Stark-effect
measurements on such selected transitions are briefly indicated.
A comparison of the molecular structures of Dicyclohexyl(N-phenylthiocarbamoyl)-phosphine and Diphenyl(N-phenylthiocarbamoy1)phosphine as determined by X-ray crystallography
Authors: Cowan SW , Hoskins BF , Tiekink ERT
Published: September 2010

The crystal and molecular structures of
the title compounds, (C6H11)2PC(S)N(H)C6H5(1)
and (C6H5)2PC(S)N(H)C6H5(2)
have been determined by single-crystal three-dimensional X-ray diffraction
techniques. Crystals of (1) are monoclinic, space group P21/c, with
eight molecules in the unit cell of dimensions a 20.541(4), b 17.784(2),
c 10.2564(9) � and β 94.54(1)�;
(2) crystallizes in the triclinic space group P1 with two molecules in the unit
cell which has the dimensions a
9.242(2), b 9.994(3), c 10.373(3) �, α 68.56(2), β 71.21(2)
and γ 86.00(2)�. Both structures were refined by a least-squares procedure,
applying anisotropic thermal parameters to all non-hydrogen atoms, with the use
of 3119 and 2971 statistically significant reflections for (1) and (2)
respectively; final R 0.055 for (1) and R 0.061 (Rw
0.062) for (2). The N, C(l), S moieties of both (1) and (2) display features
consistent with the delocalization of π-electrons. There are notable differences in some of the bond angles
between (I) and (2) which have been attributed to conformational effects
arising from variations in steric pressures; this may account for the observed
differences in reactivity between the two compounds.
The Nitration of 4,6-Disubstituted 2-Phenylphenols. Some Structural Studies
Authors: Hartshorn MP , Robinson WT , Vaughan J , White JM
Published: September 2010

Nitration of the bromophenols (4a) and (5a) give products of nitro-debromination . Reaction of 6-methyl-4-nitro-2-phenylphenol (5c) with nitrogen dioxide gives 2-hydroxy-2-phenylcyclohex-3-enones (8) and (9), and probably stereoisomers (10), (20), (21) and (22). The mode of ormation of these compounds is discussed. X-ray crystal structure determinations are reported for compounds (8) and (9).
Pigments of Marine Animals. XV. Bianthrones and Related Polyketides from Lamprometra palmata gyges and Other Species of Crinoids
Authors: Rideout JA , Sutherland MD
Published: September 2010

The range of presumably polyketidal constituents in comatulid crinoids has been
extended by examination of Lamprometra palmata gyges Bell to include three 10,10′-bianthrones derivable from the known crinoid constituents, 1,3,8-trihydroxy-6-propyl-9,10-anthraquinone and the corresponding 6-(1′-hydroxypropyl) quinone . From
other species, a 1,1′- bianthraquinone, a phenanthroperylene-7,14-quinone and probably 8- acetyl-1,2,4,5,7-pentahydroxy-9,10-anthraquinone have been identified in addition to other pigments previously known from crinoids. The polyketides present in particular comatulid crinoids may be determined by natural selection from a wide range available to crinoids generally, rather than by chemotaxonomic considerations.
Heterocyclic Amplifiers of Phleomycin. VII. Phenyl-, Tolyl-, Phenoxy- and Benzyl-pyrimidines; also Some Carbocyclic Analogues
Authors: Brown DJ , Cronin BJ , Lan S , Nardo G
Published: September 2010

Synthetic routes are described for 5-phenyl-, 5-p-chlorophenyl-, 2-p-tolyl-, 2- and 4-benzyl- and 4-phenoxy-pyrimidines, each bearing a sulfur-, nitrogen- or oxygen-linked basic side chain; also to analogous biphenyls and a diphenylmethane . These compounds were required for evaluation as amplifiers of phleomycin.
The Unambiguous Syntheses of the 2,5-Diphenyloxazole Metabolites
Authors: Jacobsen NW , Philippides A
Published: September 2010

The syntheses of the six possible monohydroxy derivatives and the N- oxide of 2,5-diphenyloxazole are described. Attempts towards the synthesis of 2,5-diphenyloxazol-4(5H)-one are also reported.
Excess Molar Volumes of Butyl Acetate+an n-Alkanol at 298.15 K
Authors: Ortega J , Paz-Andrade MI , Rodriguez-Nunez E , Romani L
Published: September 2010

Excess molar volumes VEm at 298.15 K and atmospheric pressure were calculated over the entire composition range from densities measured with a vibrating-tube digital densimeter for the binary mixtures butyl acetate + methanol, + ethanol, + propan-1-ol, + butan-1-ol, + pentan-1- ol, + hexan-1-ol, + heptan-1-ol, + octan-1-ol, + nonan-1-ol and + decan-1-ol. The excess volumes are positive over the entire composition range for these mixtures except the system butyl acetate + methanol, for which all VEm values are negative. The excess volumes show a consistent trend towards more positive values as the length of the hydrocarbon chain of the alkanol increases. The results suggest the presence of specific interactions.
Electron-Paramagnetic-Res Spectroscopy of a Trigonal Prismatic Vanadium Cage Complex - [1,8-Diammonio-3,6,10,13,16,19-hexaazabicyclo-[6.6.6]icosanato(3,6)vanadium(IV)](4+)
Authors: Comba P , Sargeson AM
Published: September 2010

An e.p.r . study of the cage complex [VIVdi(amH)sar-2H]4+ gives spin Hamiltonian parameters gX 1.974, gy 1.967, gZ 1.991, giso 1.977, AX 92×10-4 cm-1, Ay 100×10-4 cm-1, AZ 13×10-4 cm-1, Aiso 68×10-4 cm-1, viz. gX ≈ gy < gZ ≈ 2.0 and AX ≈ Ay > AZ. This is consistent with the metal centre approaching a trigonal prismatic environment and a 2A1 (D3) ground state, viz. ...d1/z2. Comparison of the spin Hamiltonian parameters from measurements in frozen and fluid solution, poly(vinyl alcohol) films and dilute powder [VIVdi(amH)sar-2H]4+ doped into the lattice of the protonated ZnII salt over a large temperature range indicates that the structures in solution and in the solid state are virtually identical. The results are discussed in relation to the known structure of the ion in the lattice [vIVdi(amH)sar -2H](S2O6)2, the sites of deprotonation of the coordinated amines and in relation to the trigonal and small rhombic distortions of the complex.
Preparations and Spectroscopic Properties of Some Germanes of the Types MexGe3H8-x, MexGe(GeH3)4-x and MexSi(GeH3)4-x
Authors: Foster SP , Leung KF , Mackay KM , Thomson RA
Published: September 2010

The preparations of MexSi(GeH3)4-x (x = 3, 2, 1, 0) and MexGe(GeH3)4-x(x = 3, 2, 1), by reaction of dry GeH3Na with the corresponding chloride, have been refined. 1,2-Me2Ge3H6, 2,2-Me2Ge3H6 and 1,2,2-Me3Ge3H5 have been prepared by the successive reactions of I2 and MeMgI on MeGe3H7. Further unstable or minor products indicated in these reactions are (GeH3)4Si, 1,1,2,2-Me4Ge3H4 and 1,2,2,3-Me4Ge3H4 together with traces of other permethyltrigermanes . Vibrational, 1H n.m.r . and mass spectra of these species are reported together with 29Si and 73Ge n.m.r . observations on the MexSi(GeH3)4-x family.
The Chemistry of Eremophila Spp. XXVI. New Viscidane Diterpenes
Authors: Forster PG , Ghisalberti EL , Jefferies PR
Published: September 2010

The structures of three new diterpene acids of the viscidane class have been elucidated by chemical and spectroscopic methods. The unusual 2-oxatricyclo [6.3.1.04,8] dodecane ring system present in one of these can be generated chemically from suitably dihydroxylated viscidanes.
Substituent Effects on the N.M.R. Spectra of Carboxylic Acid Derivatives. IV. 13C N.M.R. Spectra of para-Substituted Phenols, Phenylureas and Phenyl Propionates
Authors: Oconnor CJ , McLennan DJ , Calvert DJ , Mitha ASH
Published: September 2010

The 13C n.m.r. spectra of 9 para-substituted
phenols, 12 para-substituted phenylureas and 11 para-substituted phenyl propionates have been measured in (CD3)2SO and the observed substituent chemical shifts have been found to be non-additive with respect to those of the corresponding monosubstituted benzenes. The 1H n.m.r. spectra of the phenols and phenyl propionates and the i.r . carbonyl stretching frequencies of the phenyl propionates have also been determined. The spectral data have been treated by single parameter and dual substituent parameter linear free energy relationships ( l.f.e.r .) and σR values of best fit have been identified. In general, treatment by single parameter l.f.e.r . Are at least as satisfactory as those by DSP l.f.e.r.
The Stereochemistry of Organometallic Compounds. XXIX. Synthesis of Steroidal 1,4-Diphosphine, 1,3-Diphosphine and 1,6-Diphosphine and Their Evaluation as Ligands in Metal Catalyzed Asymmetric Synthesis
Authors: Thomson RJ , Jackson WR , Haarburger D , Klabunovsky EI , Pavlov VA
Published: September 2010

The steroidal 1,4-diphosphines 3α- and 3β-diphenylphosphino-2a-(2'-diphenylphosphinoethyl)-5α-cholestanes and their 5H-benzo[b] phosphindole derivatives have been prepared and shown to be useful ligands in asymmetric hydrogenation reactions. Interestingly the 3α- and 3β-derivatives lead to opposing enantioselection preferences when used in these reactions. A steroidal 1,3-diphosphine, 3α-diphenylphosphino-2α-diphenylphosphinomethyl-5α-cholestane, has been prepared as a mixture containing some of the 3β-epimer. The 3α-1,3-diphosphine led to similar enantioselection in hydrogenation reactions as the 3α-1,4-diphosphine, and a model is proposed to explain the sense of the enantioselectivity in the 1,4- and 1,3-diphosphines. A steroidal 1,6-diphosphine has also been prepared but leads to lower optical yields in the hydrogenation reactions. These ligands have been shown to lead to only poor to moderate optical yields when used in asymmetric carbon-carbon bond forming reactions.
The Synthesis of 4-Hydroxydithiocoumarins: A Case of Unusual Tautomer Stability
Authors: Andersonmckay JE , Liepa AJ
Published: September 2010

2'-Chloroacetophenones react with carbon disulfide in the presence of sodium hydride to form 4-hydroxydithiocoumarin anions. Kinetic protonation provides the 4-hydroxydithiocoumarins which can be tautomerized to 2-mercapto-1-thiochromones by treatment with strong acid. � Both tautomers are quite stable and do not readily interconvert. Alkylation of either 4-hydroxydithiocoumarin or 2-mercapto-1-thiochromone provides S-alkyl derivatives exclusively while acylation with acid anhydrides gives mixtures of O- and S-acyl products. Oxidation with sodium perborate yields the exocyclic monosulfoxide while m-chloroperbenzoic acid gives the exocyclic sulfone.
Studies of Australian Soft Corals. XLII. Structure Determination of New Briaran Derivatives From Briareum steckei (Coelenterata, Octocorallia, Gorgonacea)
Authors: Bowden BF , Coll JC , Patalinghug W , Skelton BW , Vasilescu I , White AH
Published: September 2010

The structure and relative stereochemistry of four new metabolites from Briareum steckei has been deduced from 2D-n.m.r. experiments at high field, and confirmed by a single-crystal X-ray determination of a minor metabolite. The new compounds are non-halogenated briaran derivatives: (1R*,2S*,3R*,5Z,7S*,8(17)Z,l0R*, llR *,12S*,14S*)- 3,14-diacetoxy- 11,12-epoxy- 18-oxobriara-5,8(17)-dien-2-yl butanoate (3), its 3-deacetoxy derivative (4), (1R*,2R*,4R*,5Z,7S*,8(17)Z,10R*, 11R *,12S*,14S*)-4,14-diacetoxy-11,12-epoxy-18-oxobriara-5,8(17)-dien-2-yl butanoate (5) and the related 2-propanoate (6). Single-crystal X-ray determinations were performed on (5) and (6).
Lewis-Base Adducts of Group 11 Metal(I) Compounds. XXIV. 1:2 Silver(I) Halide/Monodentate Amine Complexes: A Novel Structural Type in 1-2 Silver(I) Chloride Piperidine
Authors: Healy PC , Kildea JD , White AH
Published: September 2010

Recrystallization of silver(I) chloride from neat piperidine (L) yields a 1 : 2 adduct, characterized by a single-crystal X-ray study. Crystals are monoclinic, C2/c, a 20.76(4), b 6.422(7), c 20.69(2)Ǻ, β 96.9(1)°, Z 8; R 0.042 for 1061 'observed' reflections. The structure, the first determined for a 1 : 2 silver(I) chloride/monodentate amine adduct, is an infinite one-dimensional chloro-bridged polymer -AgL2-Cl-AgL2-Cl-. About the four-coordinate silver atom, Ag-Cl are 2.524(3), 2.667(3)Ǻ, Ag-N 2.385(9),
2.347(11)Ǻ, with Ag-Cl-Ag 102.62(9)°; the largest angle in the silver environment is 120.3(2)°(Cl-Ag-N).
Lewis-Base Adducts of Group 11 Metal(I) Compounds. XL. Conformational Systematics of [(N-base)1(CuX)1]∞ Orthogonal' Stair' Polymers (N-base = 'One-Dimensional Aceto-nitrile, Benzo-nitrile Ligand)
Authors: Healy PC , Kildea JD , Skelton BW , White AH
Published: September 2010

The structural chemistry of the polymeric 1:1 adducts of copper(1) halides ( CuX ; X = Cl, Br, I) with nitrile bases (exemplified by aceto- and benzo-nitrile ) has been systematically explored. Single-crystal X-ray structure redeterminations of enhanced precision have been carried out for all acetonitrile adducts (refined as orthorhombic, Pbnm , Z 4, a ≈ 13.0, b ≈ 8.5, c ≈ 4.0 � ; R 0.039, 0.030, 0.043 for No = 534, 365, 727 'observed' reflections) and the chloride and bromide benzonitrile adducts (monoclinic, P21/n, a ≈ 3.9, b ≈ 17.5, c ≈10.9 � , β ≈ 98, Z 4); R 0.046, 0.048 for No = 1452, 1209); all structures are of the common one-dimensional 'stair' polymer type. In these adducts, the ligand is essentially 'one-dimensional' with substituents well removed from the point of attachment and from interaction within the parent polymer chain. Under these circumstances, the polymer is essentially 'orthogonal' with Cu-X crosslinks at (or nearly at) right angles to the polymer axis, and containing quasi-mirror planes, the series providing reference parameters for the description of distortions observed in these polymers when more hindered bases are coordinated.
Lewis-Base Adducts of Group 11 Metal(I) Compounds. XLII. [Cu4X4L4] 'Cubane' Clusters, L = Hindered N-Base Ligand: Synthesis and Structure of the L = 2-(Diphenylmethyl)pyridine Complexes (X = Cl, Br, I)
Authors: Engelhardt LM , Healy PC , Kildea JD , White AH
Published: September 2010

The synthesis and single-crystal X-ray structure characterization of tetrameric cubane clusters of copper(1) halides with the hindered N-base ligand 2-(diphenylmethy1)pyridine are reported. The chloride, bromide and iodide structures are isomorphous , crystallizing
in the tetragonal space group 141/a, a ≈ 23, c ≈ 12 � , Z = 4 tetramers, the tetramer having crystallographically imposed 4 symmetry, well removed from the ideal 43m. In terms of each X3CuN fragment of the core, this distortion results in one of the N-Cu-X angles being enlarged by c. 30� with respect to the other two and one
Cu-X bond distance shortened. Cu-N is also shorter than is usual in a
four-coordinate environment and the cluster can be envisaged as being constructed from four quasi-linear monomers. The distortions may be attributed to interaction between the 6- and 2-α-substituent-hydrogen atoms and the halide atoms of the core. The effect diminishes with increasing halide size and increasing volume of the Cu4X4 core.
Preparation and Properties of Nitridotechnetic(VI) Acid. I. Observation of the E.S.R.-Spectrum of the [TcNF4]- Anion in Hydrofluoric Acid Solution
Authors: Baldas J , Boas JF , Bonnyman J
Published: September 2010

Nitridotechnetic (VI) acid has been prepared by the hydrolysis of Cs2TcNCl5. Dissolution of this compound in concentrated HF gave an e.s.r. spectrum due to [TcNF4: g 1.895, g 1.990, A 0.03765 cm-1, A 0.01795 cm-1, Q 0.00052 cm-1 for Tcvi ; a, 0.0052 cm-l, ay 0.0010 cm-l, az , < 0.0002 cm-1 due to F-. A comparison of the 4dxy MO coefficient, β2, with those for [TcNCI4]- and [TcNBr4]-indicates that the Tc =N bond length is greater in [TcNF4]- than in [TcNCI4]- and [TcNBr4]-.
The First Molecular Complex Containing Two Azoarenes. The Crystal Structure of Decafluoroazobenzene/Azomesitylene (1 : 1)
Authors: Bruce MI , Tiekink ERT
Published: September 2010

The crystal and molecular structures of the title compound, C12F10N2.C18H22H2,are reported. The crystal structure is comprised of stacks of alternate decafluoroazobenzene and azomesitylene molecules with the vertical separation between successive molecules being approximately 3.42 � . The stacks are aligned so that the azobenzene molecules of one stack are adjacent to the azomesitylene molecules of the neighbouring stacks; there are no significant intercolumn contacts. Crystals are monoclinic, space group P21/n with unit cell dimensions a 7.197(2), b 15.432(3), c 12.513(3) � , β 96.33(2)� , and Z 2. The structure was refined by a full-matrix least-squares procedure to final R 0.059 for 915 reflections for which 1 ≥ 3.O σ(I).
Lewis-Base Adducts of Group 11 Metal(I) Compounds. LIII. Synthesis and Structural Characterization of Binuclear μ,μ'-Dichloro-, Dibromo and Diiodo-bis[(pyridine)(triphenylphosphine)copper(I)] Complexes, and Their Pyridine-4-carbonitrile Analogues
Authors: Engelhardt LM , Healy PC , Kildea JD , White AH
Published: September 2010

Mixed base pyridine (py)/triphenylphosphine adducts of the copper(1) halides, CuX, have been synthesized for 1 : 1 : 1 stoichiometry for X = chloride and iodide; single-crystal X-ray structure determinations of these show them to be isomorphous and isostructural with that of the bromide recorded elsewhere, being �,�′- dihalo-bridged dimers , [(PPh3)( py )CuX2Cu( py )(PPh3)], monoclinic, C2/c, a ≈ 26.2, b ≈ 14.3, c ≈ 11 .2 � , β ≈ 95, Z = 4 dimers. The bromide has been isolated as a new monoclinic C 2/m polymorph, a 11 .279(8), b 14.268(6), c 13.858(4) �, β 109.33(6)�, Z=4 dimers, and details of its structure are also recorded. The structures of their pyridine-4-carbonitrile (pycn) analogues have also been determined and found to be also binuclear, with no cyano-copper interactions; these also are an isomorphous, isostructural series, monoclinic P21/n, a ≈ 15.4, b ≈ 8.1, c ≈ 17.9 � , β ≈ 101 �, Z = 2 dimers. In each series of dimers, one half of the dimer is crystallographically independent, the generators of the other half being twofold rotor (C2/c phase), mirror (C2/m phase) and inversion centre (P21/n phase) respectively.
The Structure and Absolute Stereochemistry of Pisosterol, the Principal Triterpenoid From Fruitbodies of the Fungus Pisolithus tinctorius
Authors: Gill M , Kiefel MJ , Skelton BW , White AH
Published: September 2010

The structure and absolute stereochemistry of pisosterol [(22R,23S)-24-methyIene-5 α lanost - 8-ene-3β22,23-triol 22-acetate] (3), the principal colourless constituent of the mycorrhizal fungus Pisolithus tinctorius, are established by n.m.r. experiments and a single-crystal X-ray analysis of the (3,23-) diacetyl derivative (4).
Anomalies in the Reduction of the Schiff Bases 5-(Diethylamino)-2-(phenyliminomethyl)phenol and 2-[(4-Diethylaminophenyl)iminomethyl]-phenol and Their Crystal Structures
Authors: Moloney GP , Gable RW , Iskander MN , Craik DJ , Mackay MF
Published: September 2010

Two intermediate Schiff bases, 5-( diethylamino )-2-( phenyliminomethyl )phenol(1) and 2-[(4-diethylaminophenyl) iminomethyl ]phenol(2), were encountered which proved difficult to reduce to their corresponding secondary amines with sodium borohydride . X-Ray crystallographic analyses showed that the molecules are virtually planar with intramolecular hydrogen bonding between the imino nitrogen and the phenolic oxygen. Bond lengths in the phenyl rings with the diethylamino substituents indicate a significant contribution from the quinonoid form for these ring systems.
The Formation of Monomeric and Dimeric Nitro Nitrates in the Reaction of Phenanthrene With Nitrogen Dioxide: X-Ray Crystal Structure of trans-10-Nitro-9,10-dihydrophenanthren-9-yl Nitrate
Authors: Judd MC , Hartshorn MP , Martyn RJ , Robinson WT , Wright GJ , Vannoort RW
Published: September 2010

Reaction of phenanthrene (1) with nitrogen dioxide in benzene solution gives the dimeric nitro nitrate (3), trans and cis nitro nitrates (7) and (8), and 9-nitro- (4), 3-nitro- (5) and 1-nitro-phenanthrene (6). The X-ray crystal structure of the trans nitro nitrate (7) is reported. The effect of the phenanthrene (1) concentration on product yields is reported. Gas-liquid chromatography results for the nitro nitrates (3) and (7) point to difficulties in using this technique for product analyses in reactions of phenanthrene (1) with nitrogen dioxide.
Norterpene Dienes From an Australian Marine Sponge Latrunculia brevis
Authors: Butler MS , Capon RJ
Published: September 2010

The norditerpene diene acid (4) and norsesterterpene diene acid (5), along with their corresponding methyl esters (6) and (7), were isolated from an Australian marine sponge, Latrunculia brevis, and their structures determined by detailed spectroscopic analysis, chemical derivatization and degradation. Comment is made on the possible intermediacy of dienes such as (4)-(7) in the biosynthesis of norterpene cyclic peroxides, common to other Latrunculia species from the same locality.
Cyclopentadienyl-ruthenium and -osmium Chemistry. XXXV. Some Ethynyl, Vinylidene and Related Complexes
Authors: Bruce MI , Koutsantonis GA
Published: September 2010

The syntheses of several vinylidene - and ethynyl -ruthenium complexes are described, starting from HC2SiMe3 and RuCl (L)2(η-C5H5)(L=
PPh3, PMe3; L2 = dppe ). Their properties and some reactions are reported. The metallacyclic complex [ Ru {C4H2(SiMe3)2}(PMe3)(η-C5H5)][PF6] has also been isolated. The unsubstituted complexes are very reactive; for example, MeOH adds rapidly to the vinylidene to form the C(OMe)Me derivative.
Studies on Cation Selectivities of Some Pyridine-Based Ionophores for Use in Polymer Membrane Chemical Sensors
Authors: Bates MRM , Cardwell TJ , Cattrall RW , Deady LW , Murphy K
Published: September 2010

The synthesis of some macrocyclic compounds based on 4-octyloxypyridine-2,6-dicarboxylic acid, containing sulfur and/or oxygen atoms in the 2 to 6-bridging unit, along with some non-cyclic analogues is reported. These were tested for cation selectivity in poly(vinyl chloride)-based membrane electrodes. Little selectivity was found for any ion with the oxygen-containing compounds, and none approached the selectivity for potassium reported previously for a related compound. High bonding affinities for class b acceptors, particularly Ag+ and Hg2+, were found for sulfur-containing compounds. The complexation with Hg2+ was so strong that the electrodes showed behaviour characteristic of an anion response.
Alkaloids From Two Further Amathia Bryozoan Species
Authors: Blackman AJ , Eldershaw TPD , Garland SM
Published: September 2010

Two more Tasmanian bryozoans belonging to the Amathia genus have been found to contain amathamide alkaloids. A. convoluta has given a new compound, amathamide G, while A. pinnata contains the previously described amathamide C.
Dependence of the Second Virial Coefficient of Aqueous Solutions of Small Non-Electrolytes on Partial Molar Volume and Molecular Weight of the Solutes
Authors: Kiyosawa K
Published: September 2010

The osmotic pressures of aqueous solutions of small non-electrolytes, namely ethane-1,2-diol, propane-1,2,3-triol, sucrose and raffinose , were found to be expressible by quadratic equations of the molar concentration, which indicate that these aqueous systems involve no term higher than the second virial coefficient A2. Analysis has shown that A2 mainly does not arise from non-ideality of the aqueous solutions, but its magnitude depends on the partial molar volume of the solute, more precisely on the molecular weight or van der Waals radius or volume of the solute in the aqueous solution.
The Crystal Structure of an Octaethylporphyrin Dimer Bridged by a 2,5-Disubstituted Furan
Authors: Arnold DP , Lynch DE , Smith G , Kennard CHL
Published: September 2010

The crystal structure of a dimer of 2,3,7,8,12,13,17,18-octaethylporphyrin, joined at the meso-positions through a 2,5-disubstituted furan, shows the furan ring to be almost orthogonal to the porphyrin mean planes. Bond angles and distances in the furan ring and adjacent parts of the porphyrin rings are distorted due to steric congestion involving the ethyl substituents. The dizinc complex of this bis( porphyrinyl )furan exhibits a split Soret band in its electronic spectrum; this indicates strong excitonic coupling between the porphyrin chromophores.
Structural and Solid-State 31P N.M.R. Studies of Tetrameric 1:1 Butyldiphenylphosphine Complexes of Silver(I) Halides
Authors: Bowen RJ , Camp D , Effend y , Healy PC , Skelton BW , White AH
Published: September 2010

Tetrameric 1:1 complexes of butyldiphenylphosphine (PPh2Bu) with silver halides AgX (X = Cl , Br and I) have been synthesized, and characterized in the solid state by single-crystal X-ray diffraction studies and solid-state 31P n.m.r. Crystals of [(PPh2Bu) AgCl ]4 and [(PPh2Bu) AgBr ]4 are isostructural, crystallizing in the tetragonal space group 14 with a 16.853(4), c 11.697(4) Ǻ and R 0.060 for 999 'observed' reflections for X = Cl, and a 16.944(4), c 11.893(9) Ǻ and R 0.044 for 835 'observed' reflections for X = Br. The structures consist of 'cubane' units with core distances of Ag-P 2.365(8), Ag- Cl 2.712(7), 2.682(6) and 2.569(6) Ǻ for the chloride, and Ag-P 2.408(6), Ag-Br 2.819(3), 2.806(3) and 2.670(3) Ǻ for the bromide. Crystals of [(PPh2Bu) AgI ]4 crystallize in the same space group with similar cell dimensions, a 16.559(4) and c 12.819(3) Ǻ, and R 0.053 for 638 'observed' reflections. However, the tetramers in this complex are rotated by 45° around the c axis with apparent relaxation of strain at the Ag-P bond. The ligand conformation is such that the butyl groups are oriented along the c axis rather than lying in the ab plane as found for the chloride and bromide structures. The bond distances for the I3AgP core are Ag-P 2.43(1), Ag-I 2.928(4), 2.882(4) and 2.885(4) Ǻ. The ligand substituents in this complex exhibit very high thermal motion although no disorder is resolved. Solid-state CPMAS 31P n.m.r. spectra of the chloride and bromide complexes each show a simple doublet with line spacing of 640 and 595 Hz respectively assignable to 1J(107,109Ag,31P) scalar coupling. The spectrum of the iodide complex, however, consists of a broad single peak suggestive of a high degree of disorder in the crystal lattice, consistent with the structural results.
The Binding and Reduction of Dinitrogen at an Fe4 Face of the FeMo Cluster of Nitrogenase
Authors: Dance IG
Published: September 2010

The enzyme nitrogenase is comprised of an Fe protein and an FeMo protein, for which crystal structure data are now available.1,2 The FeMo protein contains the probable site of N2 binding and reduction; this is an iron molybdenum ( FeMo ) sulfide cluster with the composition [Fe7MoS9(S-Cys )(N-His)(O,O′- homocitrate )]. A model is now proposed for the binding of N2 to the FeMo cluster of the FeMo protein of nitrogenase. The model involves the interactions of the cluster with its protein surrounds, and is supported with local density functional calculations of electronic structure, and geometry optimization. The postulated binding site is an Fe4 quadrilateral, covered but not enclosed by the side chain of an arginine residue. The N2 is bound, in various configurations involving twists of the Fe4 face and twists of the N2 molecule on the face. These configurations populate a relatively flat energy surface. The two-coordinate sulfur atoms which flank the binding site play an important role, hydrogen bonding to the protein, folding away during N2 binding, being most responsive to redox changes, and mediating the proton transfer to substrate during reduction. All attributes of the model can function in concert to provide a basic picture of the mechanism for binding, reduction, and protonation of N2.
α-1,2,3,4,5,6-Hexabromocyclohexane
Authors: Carman RM , Garner AC , Robinson WT
Published: September 2010

The X-ray crystal structure determination (130 K) and n.m.r. analysis of α-1,2,3,4,5,6-hexabromocyclohexane ('α-benzene hexabromide') are reported.
Synthesis and Structure of a Novel Silver(I) Perchlorate 2,2′:6′,2″-Terpyridine Adduct Solvated With Acetonitrile
Authors: Binsilong S , Kildea JD , Patalinghug WC , Skelton BW , White AH
Published: September 2010

Recrystallization of an equimolar mixture of silver(I) perchlorate and 2,2′:6′,2″-terpyridine ( terpy ) from acetonitrile solution yields the golden yellow crystalline adduct shown by a room-temperature single-crystal X-ray study to be [Ag3( terpy )4][( MeCN )Ag( terpy )](ClO4)4. Crystals are triclinic, Pī , a 21.48(1), b 14.525(7), c 13.506(8) Ǻ, α 68.50(4), β 80.71(4), γ 81.66(4)°, Z 2 formula units; R was 0.045 for 9681 'observed' reflections. The complex helical cation is quasi- centrosymmetric with a collinear Ag3 array. The environment of the central silver atom is planar four-coordinate, two short Ag-N distances [(2.198(5), 2.188(5)Ǻ] arising from the nitrogen atoms of outer rings of a pair of twisted terpy ligands ; the other two sites are occupied by the nitrogen atoms of the central terpy rings which bifurcate to the other silver atoms [Ag(central)-N(central) 2.624(5), 2.818(5)Ǻ; Ag(outer)-N(central) 2.704(4), 2.640(4)Ǻ], which are also coordinated by the outer ring nitrogen of the two ligands [Ag-N, 2.266(5), 2.304(4) Ǻ]. Coplanar with the latter, each outer silver atom has a further tridentate terpy coordinated [Ag-N(central) 2.362(4), 2.381(4)Ǻ; Ag-N(outer) 2.403(6)-2.573(5)Ǻ]. The [( MeCN )Ag( terpy )]+ species is also quasi-planar, Ag- NCMe being 2.174(7)Ǻ, opposed to the central ring nitrogen [2.331(5)Ǻ; Ag-N(outer) being 2.399(7), 2.433(7)Ǻ].
Studies Directed Towards the Total Synthesis of Anticapsin and Related Compounds. II. Diels-Alder Addition of N-Acyl Dehydroalanine Esters to 1-Trimethylsilyloxycyclohexa-1,3-diene
Authors: Crossley MJ , Stamford AW
Published: September 2010

In a study directed towards the total synthesis of anticapsin and related compounds, the Diels-Alder addition of N- acyl dehydroalanine esters (15)-(19) to 1-trimethylsilyloxycyclohexa-1,3-diene (6) was investigated. The cycloadditions were highly regioselective and provided 2-amino-1-trimethylsilyloxybicyclo[2.2.2]oct-5-ene-2-carboxylate derivatives (23)-(28) in moderate to good yields. A modest stereoselectivity was observed in the reactions, with the endo -adducts (23a)-(28a) favoured over the exo-adducts (23b)-(28b) by a ratio of 1.5-3.3:1. Adducts (23a) and (24a) underwent stereoselective epoxidation to the less hindered face of the olefinic double bond. Reaction of the resultant epoxides (31) and (32) with TiCl4 afforded carbolactones (34) and (35), thereby allowing the assignment of endo stereochemistry to adducts (23a) and (24a). The stereochemistry of the remaining adducts was assigned by the use of 1H n.m.r. spectroscopy.
Molecular Cocrystals of Carboxylic Acids. XIX. The Crystal Structures of Two Adducts of 3-Aminobenzoic Acid With 3,5-Dinitrobenzoic Acid: the 1:1 and the 2:2 Hydrate Cocrystals
Authors: Lynch DE , Smith G , Byriel KA , Kennard CHL
Published: September 2010

Two cocrystalline molecular adducts of 3-aminobenzoic acid (3-aba) with the aromatic carboxylic acid 3,5-dinitrobenzoic acid (dnba), [(3-aba)(dnba)](1) and [(3-aba)2(dnba)2(H2O)] (2), have been prepared and their hydrogen-bonding associations determined by means of single-crystal X-ray diffraction. Complex (1) is similar to known 1:1 complexes of 4-aminobenzoic acid with other aromatic acids, with protonation of the amine group and carboxylic acid-carboxylate hydrogen-bonding associations. However, the 2:2 hydrate complex (2) has only one hetero-pair involved in proton transfer, the other remaining neutral. With both compounds there is an extensive hydrogen-bonding network involving all substituent functional groups as well as the lattice water in compound (2).
Synthesis and Properties of Methyl-, Formyl- and Amino-Diazaphenanthrene
Authors: Chrzastek L , Mianowska B , Sliwa W
Published: September 2010

Methyl, formyl and amino derivatives of the isomeric benzo [c][1,5] naphthyridine and benzo [f][1,7] naphthyridine have been obtained, and their structures confirmed by 1H n.m.r. spectroscopy. Biological activity data (MIC) for some methyl and formyl derivatives are presented.
A quantitative model of glucose signaling in yeast reveals an incoherent feed forward loop leading to a specific, transient pulse of transcription
Authors: Kuttykrishnan Sooraj , Sabina Jeffrey , Langton Laura L. , Johnston Mark , Brent Michael R.
Published: September 2010

The ability to design and engineer organisms demands the ability to predict kinetic responses of novel regulatory networks built from well-characterized biological components. Surprisingly, few validated kinetic models of complex regulatory networks have been derived by combining models of the network components. A major bottleneck in producing such models is the difficulty of measuring in vivo rate constants for components of complex networks. We demonstrate that a simple, genetic approach to measuring rate constants in vivo produces an accurate kinetic model of the complex network that
Saccharomyces cerevisiae
employs to regulate the expression of genes encoding glucose transporters. The model predicts a transient pulse of transcription of
HXT4
(but not
HXT2
or
HXT3
) in response to addition of a small amount of glucose to cells, an outcome we observed experimentally. Our model also provides a mechanistic explanation for this result:
HXT2–4
are governed by a type 2, incoherent feed forward regulatory loop involving the Rgt1 and Mig2 transcriptional repressors. The efficiency with which Rgt1 and Mig2 repress expression of each
HXT
gene determines which of them have a pulse of transcription in response to glucose. Finally, the model correctly predicts how lesions in the feed forward loop change the kinetics of induction of
HXT4
expression.
Correction for hidden confounders in the genetic analysis of gene expression
Authors: Listgarten Jennifer , Kadie Carl , Schadt Eric E. , Heckerman David
Published: September 2010

Understanding the genetic underpinnings of disease is important for screening, treatment, drug development, and basic biological insight. One way of getting at such an understanding is to find out which parts of our DNA, such as single-nucleotide polymorphisms, affect particular intermediary processes such as gene expression. Naively, such associations can be identified using a simple statistical test on all paired combinations of genetic variants and gene transcripts. However, a wide variety of confounders lie hidden in the data, leading to both spurious associations and missed associations if not properly addressed. We present a statistical model that jointly corrects for two particular kinds of hidden structure—population structure (e.g., race, family-relatedness), and microarray expression artifacts (e.g., batch effects), when these confounders are unknown. Applying our method to both real and synthetic, human and mouse data, we demonstrate the need for such a joint correction of confounders, and also the disadvantages of other possible approaches based on those in the current literature. In particular, we show that our class of models has maximum power to detect eQTL on synthetic data, and has the best performance on a bronze standard applied to real data. Lastly, our software and the associations we found with it are available athttp://www.microsoft.com/science.
In situ growth of a PEG-like polymer from the C terminus of an intein fusion protein improves pharmacokinetics and tumor accumulation
Authors: Gao Weiping , Liu Wenge , Christensen Trine , Zalutsky Michael R. , Chilkoti Ashutosh
Published: September 2010

This paper reports a general in situ method to grow a polymer conjugate solely from the C terminus of a recombinant protein. GFP was fused at its C terminus with an intein; cleavage of the intein provided a unique thioester moiety at the C terminus of GFP that was used to install an atom transfer radical polymerization (ATRP) initiator. Subsequent in situ ATRP of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) yielded a site-specific (C-terminal) and stoichiometric conjugate with high yield and good retention of protein activity. A GFP-C-poly(OEGMA) conjugate (hydrodynamic radius (
R
h
): 21 nm) showed a 15-fold increase in its blood exposure compared to the protein (
R
h
: 3.0 nm) after intravenous administration to mice. This conjugate also showed a 50-fold increase in tumor accumulation, 24 h after intravenous administration to tumor-bearing mice, compared to the unmodified protein. This approach for in situ C-terminal polymer modification of a recombinant protein is applicable to a large subset of recombinant protein and peptide drugs and provides a general methodology for improvement of their pharmacological profiles.