bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbonyl Halides of the Group 6 Transition Metals. XXVIII. Phosphorus-31 and Selenium-77 N.M.R. Studies of Some Selenium-Group 15 Donor Complexes
Authors: Colton R , Panagiotidou P
Published: September 2010

The ligands Ph2PCH2P(Se)Ph2 ( dpmSe ) and Ph2AsCH2CH2P(Se)Ph2 ( apeSe ) have been treated with Group 6 metal pentacarbonyl halo anions, [M(C0)5X]-, the Group 6 hexacarbonyls and the carbonyl halides M(C0)4X2 (M = Mo, W, X = C1, Br). Reaction of both dpmSe and apeSe with the anions [M(C0)5X]- in the presence of silver nitrate gave the complexes M(CO)5(L-L′) (L-L′ = dpmSe or apeSe ) with the ligand coordinated in a monodentate fashion through the Group 15 donor atom. Reaction of dpmSe with the hexacarbonyls gave only M(C0)4( dpmSe ) with the ligand chelated but, in contrast, apeSe could not be chelated to metal(0) and acted only as a monodentate ligand. These differences are rationalized in terms of the structure of the ligands. The behaviour of the ligands is much more similar in the metal(11) carbonyl halide chemistry. Both formed a mixture of two isomers of M(CO)3(L-L′)X2 (L-L′= dpmSe, apeSe ) in which the ligands are chelated . In the apeSe system, n.m.r. studies show these isomers are in an equilibrium which varies with temperature at a rate which is slow on the n.m.r. timescale, but the dpmSe complexes do not interchange. On reaction with further ligand, only one of the isomers of M(CO)3( dpmSe )X2 reacts to give incomplete formation of the dicarbonyl Mo(Co)2( dpmSe )2X2, which has one dpmSe ligand chelated and the other monodentate through phosphorus. On the other hand, for the apeSe system quantitative formation of Mo(CO)2( apeSe )2X2 was observed. For the apeSe system only, bubbling CO through a solution of M(CO)2( apeSe )2X2 gave M(CO)3( apeSe )2X2 with the ligands monodentate through arsenic. Extensive 31P and 77Se n.m.r. studies are described.
Nucleophilic Substitution Reactions of Thienyl Neopentyl Substrates
Authors: Mclure FI , Norris RK , Wilson K
Published: September 2010

The reaction of the chlorides (4)-(6), which are both neopentylic and thenylic , were studied. The chloride (4), unlike its analogue (13) in the benzene series, undergoes ready solvolysis with alcohols to give the corresponding ethers, e.g. (7)-(9). The chlorides (5) and (6) react more slowly than (4) but undergo methanolysis to give the methyl ethers (11) and (12) respectively. In the dipolar aprotic solvents, dimethyl sulfoxide and dimethylformamide, the reactions of the chlorides (4), (5) and (6) with the thiolate salt (16) appear to proceed by an SN1-like, an SN(AEAE) and an SRNl process respectively.
A Novel Synthesis of the Naturally Occurring Dibenzofurans Pannaric Acid and Schizopeltic Acid
Authors: Elix JA , Parker JL
Published: September 2010

The dibenzofurans schizopeltic acid (1) and pannaric acid (2) have been synthesized by utilizing a biomimetic approach. The depside methyl 4-O-benzyllecanorate (6) has been converted into the diphenyl ether (7) in high yield by treatment with base. Appropriate modification of this diphenyl ether followed by cyclization with palladium acetate afforded the polysubstituted dibenzofurans (11) and (12) which were converted into the natural acids.
Synthesis and X-Ray Structural Characterization of WO(S2)(S2CNEt2)2 and Related Complexes
Authors: Broomhead JA , Enemark JH , Hammer B , Ortega RB , Pienkowski W
Published: September 2010

The reaction of SO2 and W(CO)3(S2CNR2)2 in dichloromethane solution under dinitrogen gives the title complex along with WS(S2)(S2CNR2)2 and Syn-W2O2(�-S)2(S2CNR2)2 (R = Me, Et, Pri , C6H5CH2; NR2 = pyrrolidinyl ). X-ray structural analysis of WO(S2)(S2CNEt2)2 reveals a seven-coordinate tungsten complex with a terminal oxo group and a dihapto - disulfido ligand in a mutually triangular arrangement. Crystals are monoclinic space group P21 1 n, with a 9.379(2), b 22.276(7), c 9.408(2), β 106.86(1)�, U 188l.1(7) �33 and Z 4.2758 independent data were refined to a weighted agreement factor 0.036.
Carbanion Rearrangements. Collision-Induced Reactions of Enolate Negative Ions Derived From Dimethyl Succinates and Hexane-2,5-Dione
Authors: Raftery MJ , Raftery MJ , Bowie JH , Bowie JH
Published: September 2010

Enolate ion MeOCOCHCH2CO2Me fragments through the intermediacy of two ion complexes [ MeOCO (CH2=CHCO2Me)] and [ MeO-(O=C=CHCH2CO2Me)]. The major fragmentations produce CH2=C=C( OMe )O-+HCO2Me and O=C=CH- CH=C( OMe ). Similar ion complexes are formed from methyl-substituted succinates , but their fragmentations are often different from those outlined above: e.g. MeOCOC (Me)C(Me)2CO2Me - [ MeOCO (M2C=CmeCO2Me)] → CH2(Me)C=C(Me)CO2- Me+HCO2Me. The corresponding enolate from hexane-2,s-dione (MeCOCHCH2COMe) fragments through the acetyl anion complex [ MeCO (CH2=CHCO2Me)].
The Dimerization of a 4-Hydroxyindenone
Authors: Davis BR , Johnson SJ , Woodgate PD
Published: September 2010

Treatment of the indenone (4) with acid gives a dimer similar to those obtained from related indenes. The behaviour of the dimer with acid and base is described.
The Aprotic Conjugate Addition-Reactions of the Carbanions of Octenyl Sulfides and Thiocarbamates With γ-Crotonolactone- Stereochemical and Mechanistic Aspects of Reactions Conducted in the Absence and Presence of Hexamethylphosphoric Triamide
Authors: Haynes RK , Schober PA , Binns MR
Published: September 2010

The lithiated carbanions of (E)- and (Z)-1-(phenylthio)oct-2-ene, (E)-1-(methylthio)oct-2-ene, S-[(E)-oct-2-enyl] N,N-dimethyl( thiocarbamate ), S-[(a-oct-2-enyl] N,N-dimethyl- ( thiocarbamate ), and (E)- and (Z)-1-(phenylsulfony1)oct-2-ene undergo conjugate addition to γ-crotonolactone (but-2-en-4-olide) in tetrahydrofuran at -70� to give as predominant products, syn and anti allylic sulfides, thiocarbamates and sulfones arising from reaction through C1 of the octenyl carbanions . Also formed are smaller amounts of syn and anti vinylic sulfides, thiocarbamates and sulfones arising by reaction through C3 of the octenyl carbanions. The carbanions of the octenyl sulfones give smaller amounts of the vinylic products than do the other carbanions. In the presence of hexamethylphosphoric triamide (hmpa), the relative amounts of the latter compounds are depressed in favour of the former. The diastereoselection of these reactions is significantly smaller than the corresponding reactions involving 4-t-butoxycyclopent-2-enone. The constitutions and stereostructures of all the products was established by analysis of 1H n.m.r. data and n.O.e. difference experiments conducted at 400 MHz. The enhancement of the amounts of the allylic at the expense of the vinylic compounds induced by the hmpa is tentatively ascribed to frontier molecular orbital effects, and suggests that the operation of chelation and charge control in the reactions of related allylic carbanions with carbonyl compounds is less important than is generally considered to be the case. The various factors which cause carbanions to undergo conjugate addition to α β-unsaturated carbonyl compounds and the role played by the hmpa in these reactions are critically discussed in terms of the model of Seyden-Penne and coworkers.
Lewis-Base Adducts of Group-11 Metal(I) Compounds. XXX. 3:1 Complexes of Triphenylphosphine With Silver(I) Halides
Authors: Engelhardt LM , Healy PC , Patrick VA , White AH
Published: September 2010

3 : 1 adducts of triphenylphosphine, PPh3, with silver halides, AgX, have been characterized for chloride, bromide and iodide by single-crystal X-ray structure determinations, the chloride as its diacetone solvate. Crystals of the chloride, [(PPh3)3AgCl].2(CH3)2CO, are triclinic, P1, a 13.654(4), b 14.059(4), c 13.970(4) �, α 84.82(2), β 87.71(2), γ 75.68(2)�, Z 2; the structure was refined to a residual R of 0.061 for No = 2428 independent 'observed' reflections. Crystals of the bromide, [(PPh3)3AgBr], are trigonal, P3, a l9.366(6), c 10.787(6) �, Z 3, R was 0.054 for No = 2362. Crystals of the iodide, [(PPh3)3AgI], are monoclinic, P2l/n, a 18.993(8), b 13.807(4), c 17.781(8) �, β 96.11(4)�, Z 4; R was 0.042 for No = 3691. Ag-Cl, Br, I respectively are 2.533(4), 2.671(6)-2.691(4) and 2.858(1) �. Ag-P for each of the three structures respectively lie in the ranges 2.558(5)-2.582(4), 2.528(3)-2.549(7)and 2.544(2)-2.780(3) �.
Compounds of Nickel(II) and Copper(II) With 3,5,5,13,13,15-Hexamethyl-1,2,6,9,12-pentaazacyclopentadeca-2,15-diene
Authors: Curtis NF , Morgan KR
Published: September 2010

Reaction of the bis-β-amino ketone 4,4,12,12-tetramethyl-5,8,11-triazapentadecane-2,14-dione diperchlorate with nickel(II) or copper(II) in the presence of hydrazine results in the formation of complexes of the tetradentate pentaaza macrocycle 3,5,5,13,13,15-hexamethyl-1,2,6,9,12-pentaazacyclopentadeca-2,15-diene hpd. Singlet ground state [Ni( hpd )] (ClO4)2, triplet ground state [Ni( hpd )(NCS)2], [Ni( hpd )A] ClO4 (A = acac -, 1/2(C2O42-), NO2-1,[Ni( hpd )(NO3)] NO3 and [Cu( hpd )](C1O4)2 were prepared. Infrared, electronic, 1H and 13C n.m.r. spectra, magnetic susceptibilities, and the kinetics of the slow acid promoted aquation reactions of the cations at 25�C in HCl/NaCl solutions (I= 1 mol 1-1) are reported.
Unusual Formation of New Indole-Containing Heterocyclic Ring Systems
Authors: Black DS , Chaichit N , Gatehouse BM , Moss GI
Published: September 2010

The oxazinoindoletrione (3) underwent reaction with aqueous ammonia in methanol or ethanol to yield the polycyclic methyl or ethyl esters (4) and (5) respectively. Reaction of trione (3) with gaseous ammonia in dry ethanol gave the aminobenzodiazepinone (7). This compound lost ammonia on heating in toluene to give compound (11) and in the presence of methanol or
ethanol gave the methyl or ethyl esters (9) and (10) respectively. The structures of compounds (4), (7) and (10) were all established by X-ray crystallography.
1,2,4-Triazines. III. The Methylation of 5,6-Dimethyl-1,2,4-triazin-3-amine and Related Compounds and the Identification of the Products by Carbon-13 Nuclear Magnetic Resonance Spectroscopy
Authors: Jacobsen NW , Dejonge I
Published: September 2010

5,6-Dimethyl-1,2,4-triazin-3-amine reacts with methyl iodide to give 3-amino-1,5,6-trimethyl-1,2,4-triazinium iodide and 2,5,6-trimethyl-l,2,4-triazin-3(2H)- imine hydriodide . The products were identified by classical methods and confirmed by 13C n.m.r, spectroscopy to establish this as a reliable technique for determining the sites of methylation in such systems. The methylation products from other alkyl-and aryl-substituted 1,2,4-triazin-3-amines are also reported.
Three New Depsidones From the Lichen Neofuscelia subincerta
Authors: Elix JA , Jenie UA , Jenkins GA
Published: September 2010

The depsidones , glomelliferonic acid (4)(8-hydroxy-3-methoxy-ll-oxo-l-(2-oxopentyl)-6- pentyl -11H-dibenzo[ b,e ] [1,4]dioxepin-7-carboxylic acid), loxodellonic acid (5) (8-hydroxy-3-methoxy-11-oxo-1-(2-oxopenty1)-6-propyl-llH-dibenzo[ b,e ][l,4]dioxepin-7-carboxylic acid) and glomellonic acid (6) (8-hydroxy-3-methoxy-1l-oxo-l,6-di(2-oxopentyl)-11H- dibenzo [ b,e ][l,4]dioxepin-7-carboxylic acid), have been isolated from the lichen Neofuscelia subincerta ( Essl .) Essl . and characterized.
Investigation of Isomer Formation of Triorganotin(IV) Complexes Involving Diorganophosphino-N-Phenyl(Thioformamide) Ligands: The Crystal and Molecular-Structure of [Diphenylphosphino-N-Phenyl(Thioformamido)]Triphenyltin, Ph3Sn[Ph2PC(S) NPh ]
Authors: Dakternieks D , Hoskins BF , Rolls CL
Published: September 2010

The isomer of Ph3Sn[Ph2PC(S) NPh] formed depends on the method of preparation. The crystal and molecular structure of the tin(IV) complex Ph3Sn[Ph2PC(S) NPh ] has been established by single-crystal X-ray diffraction techniques. The crystals are monolinic, space group P21/n, a 12.620(2), b 10.541(2), c 24.292(4)Ǻ, β 96.90(1) with Z 4; R and Rw were 0.031 and 0.034 respectively for 5632 unique reflections with I > 3σ(I). The crystals consist of discrete Ph3Sn[Ph2PC(S) NPh ] molecules. There is a tetrahedral environment about the tin atom formed by the three phenylic carbons and a sulfur atom of the [Ph2PC(S) NPh ]- ligand . Comparisons are made with the structurally similar compound Ph3Sn[(c-C6H11)2PC(S) NPh ]. On the basis of these comparisons and on earlier n.m.r . data, a favoured four-centered mechanism for insertion of dipolar PhNCS into the tin-phosphorus bond of Ph3SnPPh2 is inferred. Differences in reactivity of Ph2PC(S)N(H)Ph and (c-C6H11)2PC(S)N(H)Ph appear to result from electronic rather than steric effects.
Lewis-Base Adducts of Group 11 Metal-Compounds. XXXIII. Structural Characterization of Two Novel 'Trigonal Planar' Halobis(N-Base)Copper(I) Complexes
Authors: Dyason JC , Engelhardt LM , Healy PC , Kildea JD , White AH
Published: September 2010

Single-crystal X-ray structure determinations are recorded for two unusual trigonal planar XCuL2 species, X = halogen, L = monodentate N- base. For iodobis (2-methylquinoline)copper(I) (1) crystals are orthorhombic, P212121, a 15.079(7), b 12.592(7), c 9.585(4)Ǻ, Z 4. R was 0.028 for 1285 independent 'observed' reflections; the copper(I) environment is trigonal planar [I-Cu, 2.533(2); Cu-N, 2.034(6), 2.0l5(7)Ǻ; I-Cu-N are 119.1(2), 120.4(2) and N-Cu-N, 120.4(2)°]. For the mixed base complex bromo (3,5-dimethylpyridine)(2,4,6-trimethylpyridine )copper(I) (2), crystals are triclinic, pī , a 13.643(5), b 8.434(5), c 8.163(4)Ǻ, α 59.65(4), β 79.76(4), γ 89.68(4)°, Z 2; R was 0.046 for 1551 'observed' reflections. Br-Cu is 2.418(2); Cu-N, 1.971(5), 1.963(6)Ǻ; Br-Cu-N are 113.5(2), 110.0(2) and N-Cu-N, 136.4(3)°.
Lewis-Base Adducts of Main Group 1 Metal Compounds. V. Diaquabis(quinoline)lithium(I) Bromide Bis(quinoline)
Authors: Raston CL , Skelton BW , Whitaker CR , White AH
Published: September 2010

The title compound, an artefact of recrystallization of lithium bromide from improperly dried quinoline, has been characterized by a single- crystal X-ray structure determination. Crystals are triclinic, Pī , a 16.608(9), b 12.27(1), c 7.962(8)Ǻ, α 101.98(8),β 91.79(7),γ 92.27(6), Z 2; R was 0.058 for 2404 'observed' reflections. The cation is the first to be structurally defined for a [Li(OH2)2 (N-base)2]+ system; Li-O are 1.92(2), 1.93(2)Ǻ and Li-N 2.12(2), 2.14(2)Ǻ.
Crotaleschenine, an Alkaloid of Crotalaria leschenaultii
Authors: Smith LW , Edgar JA , Willing RI , Gable RW , Mackay MF , Suri OP , Atal CK , Culvenor CCJ
Published: September 2010

An alkaloid of Crotalaria leschenaultii DC., previously reported as crispatine and now named crotaleschenine, has been re-investigated and shown to be (7β,8α-H,12α,13α,14α)-12β-hydroxy-1,2-didehydrocrotalane-11,15-dione.1 Spectroscopic data are presented and the stereochemistry determined by X-ray crystallography. The esterifying acid of crotaleschenine is identical with that of retusine , which is thereby determined as (1a,7β,8α-H,12α,13α,14α)-12β- hydroxycrotalane-11,15-dione.
The Synthesis of Some Compounds Containing the Selenocarbonyl Group by Using Viehe's Salt/Sodium Hydrogen Selenide: an Approach to Cyclic Selenocarbonates in the Monosaccharide Series
Authors: Copeland CM , Ghosh J , McAdam DP , Skelton BW , Stick RV , White AH
Published: September 2010

The treatment of various thiols, phenols and amines with Viehe's salt (Me2N+=CCl2 Cl -), followed by addition to sodium hydrogen selenide in ethanol, can lead to useful syntheses of compounds containing the selenocarbonyl group, namely selenothiocarbamates, selenodithiocarbonates, selenothiocarbonates and selenoureas . As well, the combination of Viehe's salt/sodium hydrogen selenide allows the conversion of some carbohydrate cis vicinal diols into novel cyclic selenocarbonates, and a single-crystal X-ray diffraction structure determination of one of these selenocarbonates is reported. The treatment of these selenocarbonates with methyl iodide and various phosphorus reagents is reported, as well as some unsuccessful attempts towards tellurocarbonates and telluroureas.
The Preparation of Some β-Sulfonylacrylate Thioesters and β-Sulfonylvinyl Ketones
Authors: Haynes RK , Vonwiller SC , Stokes JP , Merlino LM
Published: September 2010

β- Sulfonylacrylate phenyl and t-butyl thioesters , and β- sulfonylvinyl ketones have been prepared by oxidation of the corresponding β-aryl- and β-alkyl- thio compounds. In one case the β- sulfonylvinyl ketone was obtained from an epoxy sulfone . The β-aryl- and β-alkyl- thio compounds were obtained by chlorination- dehydrochlorination of saturated precursors. The reactions of 3-( phenylthio ) propionyl chloride with organocadmium and Grignard reagents were used to prepare some of the saturated precursors of the β- sulfonylvinyl ketones.
The Stereochemistry of Organometallic Compounds. XXXI. Hydrocyanation of Alkynols
Authors: Jackson WR , Lovel CG , Perlmutter P , Smallridge AJ
Published: September 2010

The regioselectivity of hydrocyanation of a range of alkynols using nickel-based catalyst systems involving either triphenyl phosphite or α,α′-bis(diphenylphosphino)-o-xylene (phmep) has been investigated. The regioselectivity of the hydrocyanations involving the phosphine catalyst reflected dominant steric effects whereas results from the phosphite catalyst system showed some evidence for chelation control. Yields of nitriles from reactions based on the phosphite system were variable, whereas moderate to good yields of distilled products could be obtained consistently by using the phosphine -based system. An explanation for this variation in yield is proposed.
Geometry of Some Strained Oxygen Ring Compounds: 1,3-Benzodioxole and 2,3-Dihydro-1,4-benzodioxin (Benzodioxan). Application to the Geometry of (6aR-cis)-3-Methoxy-6a,12a-dihydro-6h-[1,3]dioxolo-[5,6]benzofuro[3,2-C] [1]benzopyran (Pterocarpin)
Authors: Vidal B , Conan JY , Lamaty G , Vardin J
Published: September 2010

The geometry of benzodioxole, benzodioxan and the strained five- membered rings of pterocarpin
are studied by the MNDO method. We show that in benzodioxole there is bond alternation towards a Kekule -like structure such as in indan (Mills-Nixon effect). In benzodioxole, owing to the smaller perimeter of the fused ring and enhanced strain, alternation is more pronounced than in indan . An explanation is offered for the strong distortion in ring angles in benzodioxole compared with indan. The effect of strain in benzodioxan and pterocarpin is discussed.
Structures of (ND4)2V(SO4)2.6D2O and (ND4)2V0.45Zn0.55(SO4)2.6D2O At 5.8 K by Neutron Diffraction
Authors: Deeth RJ , Figgis BN , Forsyth JB , Kucharski ES , Reynolds PA
Published: September 2010

The crystal structures of (ND4)2V(SO4)2.6D2O and (ND4)2V0.45Zn0.55(SO4)2.6D2O have been determined at 5.8 K by neutron diffraction. The 663 and 857 unique reflections measured respectively refined to give R(F2) 0.035 and 0.045. The crystals are monoclinic, P21/a, isostructural with the other members of the series of Tutton salts. The V-O bond length of 211.8 pm [210.4 pm for mean (V/Zn)-O in the solid solution with Zn] is intermediate between these for the Mn (214.9 pm) and the Ni(205.5 pm) salts. It is shorter than the value determined by X-ray diffraction at 295 K. The major departure from a regular VO6 octahedron is a shortened V-O(9) bond, such as is observed in the other Tutton salts, to give a tetragonal distortion.
Coordination Chemistry of the Calixarenes. II. Europium(III) and p-t-Butyl Calix[6]arene
Authors: Engelhardt LM , Furphy BM , Harrowfield JM , Kepert DL , White AH , Wilner FR
Published: September 2010

The possible nature of p-t-butyl-calix [6] arene complexes of lanthanide elements has been explored by determination of the single-crystal X-ray structure of a complex with a 1:2 europium/ ligand ratio, obtained from dimethylformamide (dmf ≡ Me2NCHO) solution. This complex is formulated as [ Eu (LH4)(Me2NCHO)6(OH)].LH6.~4Me2NCHO (LH6 = p-t-butyl-calix [6] arene) on the basis of the structure determination. Crystals are monoclinic, P21/n, a 36.11(3), b 23.35(2), c
21.85(2)Ǻ, β 97.46(6)°, Z = 4 formula units; R was 0.11 for 8488 'observed' reflections. The complex is remarkable in that the only interaction of either of the two calixarene ligands (one presumably doubly or triply deprotonated ) with the eight-coordinate europium atom is by way of one behaving as monodentate, the other having no interaction. Eu -O( calix ) is 2.35(1) Ǻ; Eu -O( dmf )6 range from 2.38(2) to 2.49(2)Ǻ, and Eu -O(H ½?) is 2.49(2)Ǻ.
Cementation of Lead From Lead Sulfate Slurries. II. Reaction-Mechanisms With Zinc Precipitant
Authors: Bear IJ , Flann RCA , Woods R
Published: September 2010

The cementation of lead from aqueous slurries of lead sulfate with zinc precipitant in stirred-bed reactors is characterized by two main reaction profiles. The mechanisms giving rise to both these profiles involve dissolution of lead sulfate and subsequent reaction of lead ions with zinc metal. Dissolution is slower than deposition when the latter step is unimpeded, and limits the overall rate. When mechanism 1 is operative, the reaction proceeds initially at a rapid rate but, after a relatively short period, slows significantly and may even stagnate. This behaviour arises from the lead depositing mainly on the outer surface of the lead/zinc agglomerates which impedes subsequent transport of liquor ions to and away from reaction sites. Mechanism 2 involves a slower initial rate but the reaction proceeds to completion at a steady rate. The absence of inhibition in this regime is associated with the formation of basic zinc sulfate crystals within the lead/zinc agglomerates. It is considered that this process keeps the agglomerates porous and allows continuous free access of ions of the liquor to the zinc precipitant. Thus, the relative rates of the dissolution of lead sulfate and the development of bzs determines which mechanism is operative in each situation. The rate of diffusion of sulfate into the agglomerates is an important factor in the formation of the bzs. The implications of these findings for the treatment of industrial residues are briefly discussed.
Synthesis of 5-Aminopyrazole-4-carbonitriles
Authors: Dooley MJ , Quinn RJ , Scammells PJ
Published: September 2010

A one-pot reaction between substituted hydrazines, malononitrile and triethyl orthoformate leads directly to the formation of 1-substituted 5-aminopyrazole-4-carbonitriles. The scope and limitations of this synthetic procedure are discussed in relation to the well established synthesis of these compounds via substituted hydrazines and ethoxymethylenemalononitrile.
The Diepoxides of Thymoquinone
Authors: Carman RM , Duffield AR , Lambert LK , Robinson WT , Vandonge n
Published: September 2010

Structures for the cis and trans diepoxides of thymoquinone are assigned from n.m.r. and X-ray crystallographic studies.
Aluminium-27 N.M.R. Studies of Aluminum Fluoro Complexes in Dichloromethane Solution: Evidence for the Tetrafluoroaluminate Anion
Authors: Colton R , Eller PG
Published: September 2010

Mixed aluminium chloro/fluoro anions are formed in dichloromethane solution by the interaction of AICl3 and [Ph3PhCH2P][H2F3]. Aluminium-27 n.m.r. studies are restricted to the stoichiometric ranges F/AI from 1 : 1 to 3 : 1 and F/AI > 8 : 1. Between these limits rapid precipitation reactions occur. In the fluoride-rich stoichiometric range there is rapid exchange on the n.m.r. time scale between the aluminium fluoro anion and free fluoride, so that a direct identification of the species by the multiplicity of the resonance is not possible. Indirect evidence strongly suggests that the aluminium species is [AIF4. In the F/AI stoichiometry range from 1 : 1 to 3 : 1 aluminium-27 resonances were observed for all the other possible [AICIxF4-x]- species. Studies on the aluminium \iodo/fluoro system support the identification of [AIF4]-, but the system is labile and the mixed iodo/fluoro species undergo rapid disproportionation.
The Conversion of Light Naphtha Into Aromatics by Using Promoted Zeolite Catalysts
Authors: Berti G , Moore JE , Salusinszky L , Seddon D
Published: September 2010

Zeolites of the ZSM-5 family are poor for converting liquid paraffins into aromatics, but commercially available H-ZSM-5 can be effectively promoted with zinc or gallium. A gallium-promoted zeolite was used for the conversion of pentane and a natural-gas condensate into aromatic-rich liquid products. Optimum performance was obtained at temperatures of 475�C and weight-hourly space velocity of 1 h-1. The aromatic products were principally benzene, toluene and xylene, with the benzene content increasing with increasing conversion temperature. Operation of the catalyst at high severity (high temperature, low space velocity) produced a liquid product containing over 90% of aromatics. Lower severity produced less aromatics but higher overall liquid yield.
Electronic Spectroscopy of Mixed Cyclophanes: [2.2](9,10)Anthraceno(1,4)naphthalenophane
Authors: Ferguson J , Robbins RJ , Wilson GJ
Published: September 2010

The absorption and fluorescence spectra of [2.21(9,10) anthraceno (1,4) naphthalenophane are reported. The anisotropy of the absorption bands was measured by two methods, ( i ) from fluorescence polarization ratios in a rigid glass and (ii) from single crystal absorption spectra at 23 K. The two states arising from the 1La states of the two chromophores were identified together with two states arising from other chromophore 1B2u states. Two states arising from the 1La states of the two chromophores were also identified. Whereas a coupled chromophore model accounts reasonably well for the latter two states, the energies and intensities of the bands arising from 1La chromophore states cannot be reconciled with this approach. Long axis polarized absorption intensity lying under the 1La, bands appears to be vibronically induced and not due to the 1Lb states. The absorption spectrum, fluorescence spectrum and fluorescence polarization ratios of a stable dimer were also observed. Its structure is similar to that of the stable dimer of anthracene in which the molecular long axes are parallel but the short axes make an angle of about 70� with each other.
Reactions of 4-Methyl-1-(1′-methylethyl)-4-nitrocyclohexa-2,5-dien-1-yl Acetates With Nitrogen Dioxide; Towards a Mechanism for the Formation of Polynitro Cyclohexenyl Esters on Reaction of p-Cymene With Nitrogen Dioxide in Acetic Anhydride
Authors: Abell AD , Hartshorn MP , Robinson WT , Waller AG , Wright GJ
Published: September 2010

The acetoxy nitro diene (21), the C3-epimeric 3,4,6-trinitro-5-nitratocyclohexenes (24) and (25), the 3,6-dinitro-5-nitratocyclohexa-1,3-diene (29), and the 3,6-dinitro-5-acetoxycyclohexa-1,3- diene (32) are identified as probable intermediates in the formation of polynitro cyclohexenyl esters (4)-(13) on reaction of p-cymene with nitrogen dioxide in acetic anhydride; probable reaction pathways are discussed. The X-ray crystal analysis of 4-methyl-1-(1′-methylethy1)-t-5-nitrato-r-3,t-4,c-6-trinitrocyclohexene (24) is reported.
Potential Ambergris Odorants From Abietic Acid
Authors: Cambie RC , Franich RA , Larsen D , Rutledge PS , Ryan GR , Woodgate PD
Published: September 2010

In contrast to literature
reports the rearrangement of abietic acid (1) catalysed by 96% sulfuric acid gives a mixture (3 : 1) of two dienoic acids (19) and (27) whose structures have been established by spectral means. Compounds containing the diene system are unstable, severely limiting their use in synthesis. However, removal of the diene functionality affords stable compounds which, despite difficulties in stereochemical control, are suitable for further modification. The synthesis of compounds containing a five- membered C-ring common to a class of potential amber odorants is reported.
Reactions of Epoxides Derived From 2′-(3″-Methylbut-2″-enyl)trifluoroacetanilides
Authors: Raner KD , Skelton BW , Ward AD , White AH
Published: September 2010

The intramolecular nucleophilic ring opening of the epoxides derived from 2′-(3″-methylbut-2″-enyl) trifluoroacetanilides has been investigated under both acidic and basic conditions. Boron trifluoride caused rearrangement of the epoxides to a ketone but no cyclization. Potassium carbonate in methanol caused regiospecific opening of the epoxides and generated dihydroindole products. The formation of a five-membered ring was confirmed by a single-crystal X-ray study of one of the products. The epoxides hydrolysed very readily in acidic conditions; the structure of one of the diol products was confirmed by a single-crystal X-ray study.
An Xα ab initio Calculation of the Charge and Spin-Density in Cs3Mo(NCS)6 Crystals Compared With Experiment
Authors: Figgis BN , Reynolds PA
Published: September 2010

We have performed ab initio discrete variational Xα calculations on a Cs18[Mo(NCS)6]15+ cluster, with the external electric field appropriate for a Cs3Mo(NCS)6 crystal. The calculations show both σ and π bonding, and also the participation of diffuse molybdenum- centred orbitals . Compared with the charge density experiment these effects are qualitatively correct but are underestimated. We performed further calculations successively removing the external electric field and the 18 Cs+ neighbours . The effects on the calculated metal- ligand bonding in the complex ion are negligible. This is not in agreement with experiment, so that these calculations which invoke only electrostatic effects and orthogonality with neighbouring ions and which also use only simple basis sets are not adequate. Further calculations on the Cr(NCS)63- and W(NCS)63- ions show increasing covalence from chromium to tungsten as expected. The spin transfer to the ligand is calculated to triple, but charge transfer is almost constant.
The Pyrolysis of Phenylnaphthalenedicarboxylic Anhydrides: Products of Ring Contraction and of Radical Cyclization
Authors: Anderson MR , Brown RFC , Coulston KJ , Eastwood FW , Ward A
Published: September 2010

Naphthalene-1,2,-dicarboxylic anhydrides with neighbouring phenyl substituents give on flash vacuum pyrolysis (850-900°/0.02-0.04 mm) ring-contracted carbenes which insert into the phenyl groups. The 8- phenyl anhydride (7) gives acephenanthrylene (10) as the major product, and the 3-phenyl anhydride (15) gives 1,2 : 4,5-dibenzopentalene (indeno [2,1-a]indene) (18). The anhydrides (7) and (15) were � synthesized by pyrolysis of the corresponding 1-naphthylmethyl propynoates (2) and (13) through a new one-step process of intramolecular Diels -Alder addition/retro-Diels -Alder elimination of acetylene. 1-Phenylnaphthalene-2,3-dicarboxylic anhydride (19) on pyrolysis at 960°/0.02 mm gives fluoranthene (11) as the major product. The behaviour of the 1-C6D5 compound (24) suggests involvement of a radical cyclization process.
A Variant of Peterson Olefination: Nitrophenyl-Substituted Methylenecyclopropa[b]naphthalenes
Authors: Halton B , Lu Q , Stang PJ
Published: September 2010

The successful use of a gem-disilyl compound in Peterson olefination with nitrosubstituted aromatic aldehydes and ketones is achieved for 1,1-bis( trimethylsilyl )-1H-cyclopropa[b]naphthalene (9) by employing potassium fluoride in acetonitrile and using a catalytic quantity of tetrabutylammonium fluoride as the fluoride ion transfer agent.
The Synthesis of the Dimer and Trimer Ether-Linked Components of Hematoporphyrin Derivative
Authors: Byrne CJ , Morris IK , Ward AD
Published: September 2010

The preparation is described of all of the likely dimer and trimer ether-linked components of the anticancer material known as hematoporphyrin derivative. The hydroxyethyl side chain of one porphyrin, related to hematoporphyrin, reacts readily with a bromoethyl system derived from the same, or similar, hematoporphyrin -derived porphyrin to form a diporphyrin ether. The coupling reaction can be controlled to occur in situ, allowing the preparation of a symmetrical ether-linked dimer , or separately to provide an asymmetrically substituted porphyrin dimer . The bromoethyl groups can be formed from either the hydroxyethyl groups or, more slowly, from a vinyl side chain by using hydrogen bromide in dichloromethane. Ether-linked porphyrin trimers can be prepared by reacting a dibromoethyl system with 2 equiv. of a hydroxyethyl -containing porphyrin or by further reaction of an initially formed dimer. Hydroxyethyl side chains in the dimers and trimers are best obtained by reduction of an acetyl group. Some spectral properties of the products are described.
Synthesis of Casein-Related Peptides and Phosphopeptides. VIII. The Synthesis of Ser(P)-Containing Peptides by the Use of Z-Ser(PO3R2)-OH Derivatives
Authors: Perich JW , Alewood PF , Johns RB
Published: September 2010

.The synthesis of five Z-Ser(PO3R2)-OH (R = phenyl, ethyl, methyl, benzyl, t-butyl) derivatives is described by a simple three-step synthetic procedure which features the use of either (A) diphenyl or dialkyl phosphorochloridate /pyridine or (B) dialkyl N,N-diethylphosphoramidite/1H-tetrazole-m-chloroperoxybenzoic acid for the phosphorylation of the serine hydroxy group. The benzyl phosphate derivative, Z-Ser(PO3Bzl2)-OH, was used in the benzyloxycarbonyl mode of peptide synthesis for the preparation of Z-Ser(PO3Bzl2)-Leu-OBzl and Z-Ser(PO3Bzl2)-Ser(PO3Bzl2)- OBzl which were deprotected by palladium- catalysed hydrogenolysis to give Ser(P)-Leu and Ser(P)-Ser(P) in high yields and high purity.
Botryococcenone, an Oxygenated Botryococcene From Botryococcus braunii
Authors: Summons RE , Capon RJ
Published: September 2010

A new botryococcene (5) incorporating an unprecedented ketone functionality has been identified in the lipid extract of an Australian collection of the green alga Botryococcus braunii Kutzing . The structure was established by detailed n.m.r. and mass spectroscopic analysis. A saturated hydrocarbon (8) prepared from this ketone by catalytic hydrogenation and Wolff-Kishner reduction has a different carbon skeleton to that of (9) prepared by hydrogenation of the co-occurring C33 botryococcene.
Synthesis of Casein-Related Peptides and Phosphopeptides. X. A Modified Method for the Synthesis of Ser(P)-Containing Peptides Through 4-Bromobenzyl Phosphate Protection
Authors: Perich JW , Johns RB
Published: September 2010

The three 4-halobenzyl phosphoramidite reagents di (4-fluorobenzyl) N,N- diisopropylphosphor-amidite, di (4-chlorobenzyl) N,N- diisopropylphosphoramidite and di (4-bromobenzyl) N,N-diethylphosphoramidite were prepared and used for the efficient phosphite-triester phosphorylation of isobutyl alcohol. While all three 4-halobenzyl groups were cleaved at similar rates from the 4-halobenzyl phosphorotriesters by 4 M HCl/dioxan or 50% CF3CO2H/CH2Cl2, the 4-bromobenzyl group had greater stability than either the 4-fluorobenzyl or 4-chlorobenzyl groups in formic acid or 1 M HCl /acetic acid solutions. The protected 4-bromobenzyl derivative, Boc-Ser(PO3BrBzl2)-OH, was prepared by a novel one-step procedure which featured di-4-bromobenzyl N,N- diethylphosphoramidite as phosphitylating agent. This derivative was used for the synthesis of Boc-Glu ( OBzl )-Ser(PO3BrBzl2)- Leu-OBzl by the Boc mode of peptide synthesis with 98% formic acid being used for the cleavage of the Boc group. Palladium-catalysed hydrogenolysis of the protected Ser(PO3BrBzl2) tripeptide in formic acid gave zwitterionic Glu -Ser(P)-Leu in high overall yield.
Kinetic Determination of Binding Constants for Cyclodextrin Inclusion of pada in Solution
Authors: Demont PM , Reinsborough VC
Published: September 2010

Competition kinetics was used to determine the binding constants of the dye pyridine-2-azo-p-dimethylaniline ( pada ) with β- cyclodextrin (β-CD), γ- cyclodextrin (γ-CD), 2,6-O-dimethyl-β-cyclodextrin ( dmβ ), 2,3,6-O-trimethyl-β-cyclodextrin ( tmβ ) and hydroxypropyl-β-cyclodextrin ( hpβ ) at 25.0°. Stopped-flow spectroscopy was used to monitor the change in kinetics after cyclodextrins had been added to the Niaq2+ and pada reactant solutions. The values of the binding
constants/dm3 mol-1 with pada were 300 for β-CD, 40 for γ-CD, 550 for dmβ, 210 for tmβ , and 350 for hpβ.
Molecular Cocrystals of Carboxylic Acids. I. The Crystal Structures of the Adducts of Indole-3-acetic-Acid With Pyridin-2(1H)-one, 3,5-Dinitrobenzoic Acid and 1,3,5-Trinitrobenzene
Authors: Lynch DE , Smith G , Byriel KA , Kennard CHL
Published: September 2010

Three molecular cocrystal adducts of the plant hormone indole-3-acetic acid ( iaa ) have been prepared and their structures determined by X-ray diffraction. They are indole-3-acetic acid-bis [pyridin-2(1H)-one] (1), indole-3-acetic acid-3,5-dinitrobenzoic acid (2) and indole-3-acetic acid-1,3,5-trinitrobenzene (3). Complexes (2) and (3), which may be prepared in a solid-state reaction, are orange and are structurally similar, having significant π-π indole -benzene ring interactions. However, the colourless complex (1) shows no π-π ring interactions. In complex (2), the 3,5-dinitrobenzoic acid molecules form hydrogen-bonded cyclic dimers (O…O, 2.64 Ǻ), while in (3) the indole-3-acetic acid molecules form dimers (O…O, 2.66 Ǻ). This feature contrasts with the structure of adduct (1) in which the pyridin-2(1H)-one molecules exist as dimers [N…O, 2.79, 2.74 Ǻ] analogous to those found in the parent compound.
Photochemical and Thermal Decomposition of Bis(3-chloro-2-methylphenyl)diazomethane
Authors: Lai YH
Published: September 2010

The reactions of diarylcarbene (2c) generated from the photolytic and thermal decomposition of diaryldiazomethane (1c) were investigated. The effect of steric hindrance in (2c) was insufficient to stabilize the carbene under the photolytic conditions to allow direct dimerization to form the olefin. In the
thermal decomposition of (1c), only the azine (3c) was obtained. Both these observations are different from those reported for dimesitylcarbene (2b), and indicate that (2b) undergoes reactions (dependent largely on severe steric hindrance) which are not generally applicable to di-o-tolylcarbene and its derivatives.
Synthesis of Casein-Related Peptides and Phosphopeptides. XV. The Efficient Synthesis of Multiple-Ser(P)-Containing Peptides
Authors: Perich JW , Johns RB
Published: September 2010

The synthesis of Ac-Ser(P)- NHMe and multiple-Ser(P)-containing peptides Ac-Ser(P)-Ser(P)-NHMe and Ac-Ser(P)-Ser(P)-Ser(P)- NHMe is described. The use of Boc -Ser(PO3Ph2)-OH in the Boc mode of peptide synthesis for the preparation of the protected Ser(PO3Ph2)-containing peptides was followed by platinum-mediated hydrogenolytic deprotection.
A Synthesis of the Lichen Dibenzofuran Pannaric Acid 2-Methyl Ester and Its Isomer 3-O-Methylpannaric Acid
Authors: Elix JA , Naidu R , Laundon JR
Published: September 2010

A total synthesis of pannaric acid 2-methyl ester (2-methyl hydrogen 3,9-dihydroxy-1,7-dimethyldibenzofuran-2,6-dicarboxylae) (1) and 3-O-methylpannaric acid (9-hydroxy- 3-methoxy-1,7-dimethyldibemofuran-2,6-dicarboxylic acid) (2) has been achieved through a biomimetic-type approach by using palladium(n) acetate in the key cyclization step. The acid (1) was shown to be identical to a major metabolite of the lichen Roccella capensis and a minor or trace constituent of the lichens Leproloma diffusum and L. vouauxii.
Solution Phase Synthesis of Glu-Abu(P)-Leu by Using Z-Abu(PO3Et2)-OH
Authors: Perich JW , Valerio RM , Johns RB
Published: September 2010

This paper describes the synthesis of the 2-amino-4-(phosphono)butanoyl-containing peptide H-Glu-Abu(P)-Leu-OH.CF3CO2H by the use of Z-Abu(PO3Et2)-OH for the solution phase synthesis of Boc-Glu(Obut)-Abu(PO3Et2)-Leu-Obut (mixed-anhydride method) followed by acidolytic cleavage of the t-butyl groups, and final removal of the ethyl groups from Glu- Abu(PO3Et2)-Leu by treatment with 10% bromotrimethylsilane in acetonitrile. Although silylitic cleavage of the peptide was facile, the slow dissolution of the peptide in the reaction solvent suggests that deprotection of the Abu(PO3.Et2) residue has not yet been optimized.
Potentiometric Sensors Based on Macrocyclic Ligands: 1,8-Naphthyridine and 1,10-Phenanthroline Derivatives
Authors: Cardwell TJ , Cattrall RW , Deady LW , Murphy KA , Tan SS
Published: September 2010

The synthesis of some macrocyclic compounds based on 1,8-naphthyridine and 1,10-phenanthroline with rings containing four and five oxygen atoms is reported. These compounds were tested for cation selectivity in poly(vinyl chloride)-based potentiometric sensors. Nernstian esponse was observed towards the potassium ion but with low discrimination for potassium in the presence of other cations. Dimethyl 4-octyloxy-1,10-phenanthroline-2,9-dicarboxylate, a precursor to one of the macrocyclic series, showed a high preference for divalent cations such as Zn2+, Ba2+, Cu2+ and Co2+. .
The Crystal Structure of Indospicine Hydrochloride Hydrate
Authors: Hegarty MP , Kennard CHL , Byriel KA , Smith G
Published: September 2010

The crystal structure of the hepatotoxic amino acid indospicine [L-6-amidino-2-aminohexanoic acid, (S)-2,7-diamino-7-iminoheptanoic acid], as its hydrochloride hydrate, has been determined by X-ray diffraction and refined to a residual R 0.036 for 845 observed reflections collected at 173 K. Crystals are orthorhombic, space group P 22121 with 8 molecules in a cell of dimensions a 5.1541(4), b 14.083(1), c 31.781(3) � . The structure is consistent with the one previously derived from chemical data but with the presence of a terminal amidinium ion and an α-amino acid zwitterion pair. The two independent molecules in the asymmetric unit are conformationally different and form a head-to-tail packing motif linked by NH(amidino)…O(carboxyl) hydrogenbonds (N…O,2.80, 2.85 � ). The structure also features extensive hydrogen bonding involving the water of solvation.
Preparation and Properties of a Glycerolatocalcium Complex
Authors: Taylor RM , Slade PG , Aldous GL , Wilding IR , Siddiqui O , Whitehouse MW
Published: September 2010

The synthesis of a glycerolatocalcium complex has been achieved by heating precipitated calcium hydroxide and glycerol to above 180�C in a microwave oven. The complex has the formula C3H6CaO3, and therefore it appears to have a molecular structure similar to that of the cobalt and zinc analogues. X-Ray powder and single-crystal data are consistent with the complex having an orthorhombic unit cell with a 6.420 �0.006, b 7.930 � 0.010, c 8.967 � 0.010 � and volume of 456.51 � 0.69 � 3. Experiments in vivo (rats) and in vitro were conducted to demonstrate the transdermal permeation that occurred after topical application of this complex. The experiments were aimed at delivering therapeutic amounts of calcium by the transdermal route.
The Ground State in Cs2KFe(CN)6 From Single-Crystal Magnetic Properties
Authors: Reynolds PA , Delfs CD , Figgis BN , Moubaraki B , Murray KS
Published: September 2010

The single-crystal magnetic susceptibilities from 4.5 to 300 K, and the magnetizations at 4.5 K from 0.25 to 5 T, of Cs2KFe(CN)6 along a, b and c* are reported. The data are fitted well by a crystal field model with splitting of the ground-state 2T2g term of the hexacyanoferrate (III) ion. The three variable parameters of the model were the two representing the low-symmetry splitting of the t2g orbitals, and the effective reduction in the orbital angular momentum. Four other parameters were fixed at values known or estimated from other experiments on hexacyanoferrate (III) ions, including polarized neutron diffraction which determines the orientation of lower-symmetry crystal field components. The crystal field has only inversion symmetry with respect to the ligand axes, with a non-cubic component which is almost uniaxial with respect to the a,b,c * axis system.
On the Crystal Structure of Bi2Te4O11
Authors: Rossell HJ , Leblanc M , Ferey G , Bevan DJM , Simpson DJ , Taylor MR
Published: September 2010

Bi2Te4O11 is monoclinic, space group P21/n; the lattice parameters derived from a Guinier powder pattern ( Si standard) are: a = 6.9909(3), b = 7.9593(3), c = 18.8963(8) � , β = 95.176(3)�, Z = 4, V = 1047.15 �. The structure was solved independently from both single-crystal X-ray data and a combination of X-ray and neutron powder data. It is an anion-deficient superstructure of fluorite in which can be recognized the ordered intergrowth of fluorite-type Bi2Te2O7 and rutile-type Te2O4. Lone-pair electrons are stereochemically active.
Oxidation of Nickel(II) and Manganese(II) by Peroxodisulfate in Aqueous Solution in the Presence of Molybdate. Crystal Structure of the (NH4)6[NiMo9O32].6H2O Product
Authors: Dunne SJ , Burns RC , Lawrance GA
Published: September 2010

Oxidation of Ni2+,aq, by S2O82- to nickel(IV) in the presence of molybdate ion, as in the analogous manganese system, involves the formation of the soluble heteropolymolybdate anion [MMogO32]2- (M = Ni, Mn ). The nickel(IV) product crystallized as (NH4)6 [NiMogO32].6H2O from the reaction mixture in the rhombohedra1 space group R3, a 15.922(1), c 12.406(1) � ; the structure was determined by X-ray diffraction methods, and refined to a residual of 0.025 for 1741 independent 'observed' reflections. The kinetics of the oxidation were examined at 80 C over the pH range 3.0-5.2; a linear dependence on [S2O82-] and a non-linear dependence on l/[H+] were observed. The influence of variation of the Ni/Mo ratio between 1:10 and 1:25 on the observed rate constant was very small at pH 4.5, a result supporting the view that the precursor exists as the known [NiMo6O24H6]4- or a close analogue in solution. The pH dependence of the observed rate constant at a fixed oxidant concentration (0.025 mol dm-3) fits dequately to the expression kobs = kH [H+]/(Ka+[H+]) where kH = 0.0013 dm3 mol-1 s-1 and Ka = 4-0x10-5. The first-order dependence on peroxodisulfate subsequently yields a second-order rate constant of 0.042 dm3 mol-1 s-1. Under analogous conditions, oxidation of manganese(II) occurs eightfold more slowly than oxidation of nickel(II), whereas oxidation of manganese(II) by peroxomonosulfuric acid is 16-fold faster than oxidation by peroxodisulfate under similar conditions.
The Preparation and Crystal Structure of 2-Phenoxypropenoic Acid
Authors: Campbell M , Mcleish MJ , Lynch DE , Smith G , Byriel KA , Kennard CHI
Published: September 2010

The potential herbicide 2-phenoxypropenoic acid has been synthesized, and its structure has been determined by X-ray methods and refined to a residual R 0.068 for 564 observed reflections. Crystals are orthorhombic, space group Pbca with Z 8 in a cell of dimensions a 5.6547(9), b 9.263(2), c 31.76(1) � . The carboxylic acid groups form centrosymmetric hydrogen-bonded cyclic dimers [O…O 2.62(1) � ], while the oxypropenoic acid side chain is essentially planar but inclined to the plane of the benzene ring [dihedral angle 71.5(7)°].
The Structures of Some Zirconium(IV) Chromium(III) Basic Sulfates Containing New Heteropolyanions
Authors: Gatehouse BM , Platts SN
Published: September 2010

Three complexes (A)-(C), MI4 [Zr6Cr4O8(OH)8(SO4)8(H2O)4].yH2O, where MI4 is Cs2.78- Na1.22 (A), Na4 (B) or not present (C), in which (A) and (B) contain the same ZrIV-CrIII heteropolyanion and (C) contains a structural isomer of it, have been crystallographically characterized with varying degrees of refinement. A fourth complex (D), [Zr6Cr4O8(OH)8(SO4)5(DL-α-Ala)4(H2O)4]n+ hydrate, in which some of the sulfate groups that form part of the heteropolyanion have been replaced by alanine (Ala) molecules, is also described. The heteropolyanion [it has 4 crystallographic symmetry in (A), no symmetry in (B)] is best described as an octahedron of eight-coordinate ZrIV ions (intermediate between square-antiprismatic and dodecahedral stereochemistry) with CrIII octahedra and sulfate tetrahedra bound to it. In (C), two CrIII octahedra and two sulfate groups have been rotated with respect to the octahedron of zirconium ions leaving an unsymmetrical heteropolyanion, while in (D) the heteropolyanion has twofold symmetry and is similar to that in (A) and (B) except for the presence of alanine in place of some sulfate groups.
An N.M.R. Investigation of Polarization of Pyridine by +R Substituents and a Proposed New Method for Determination of the Substituent Resonance Parameter (σR)
Authors: Hatton PM , Sternhell S
Published: September 2010

The previously established 1H n.m.r. method of probing bond order1 has been used to show that electron-donating (+R) substituents at C2 of pyridine cause significant ground-state polarization of the heteroaromatic system. This has led to a new and independent method of estimating the substituent resonance parameter (σR ).