bluuebunny/crossref_metadata_2025 huggingface dataset:
Iron(II) and Nickel(II) Complexes of 2,6-Di(Thiazol-4-Yl)Pyridine and Related Ligands: Magnetic, Spectral and Structural Studies
Authors: Baker AT , Goodwin HA
Published: September 2010

2,6-Di(thiazol-4-yl)pyridine
(1a), 2,6-di(2-methylthiazol-4-yl)pyridine (1b) and 2,6-di(2-phenylthiazol-4-yl)pyridine (1c) have been prepared by Hantzsch syntheses from 2,6-di(ω- bromoacetyl )pyridine and the appropriate thioamide. Bis ( ligand ) iron(II) and nickel(II) complexes of (1a) and (1b) have been prepared but no metal complexes of (1c) were isolated. The bis ( ligand ) iron(II) complexes of (1a) are low-spin whereas those of (1b) undergo thermally induced spin-transitions, both in the solid state and solution. The field strengths of the ligands , determined from the spectra of their nickel(II) complexes, correlate well with the observed magnetic behaviour of their iron(II) complexes. The structure of [FeL2][ClO4]2.H2O, L = (1a), was determined by single-crystal X-ray diffractometry . The complex cation has the meridional configuration with the ligand functioning as an approximately planar tridentate. The structural parameters relating to the Fe-N6 coordination sphere are remarkably similar to those found for bis (2,2′:6′, 2′- terpyridine )iron(II) bis ( perchlorate ) monohydrate.
The Synthesis of New Meta-Depsides From Ramalina Lichens
Authors: Elix JA , Wardlaw JH
Published: September 2010

The total synthesis of the lichen depsides 4′-O-methylnorsekikaic acid (2), 4′-O-methylnorhomosekikaic acid (7), 4′-O- methylnorcryptochlorophaeic acid (8)
and 4′-O-methylcryptochlorophaeic acid (9) is reported, and the natural occurrence of these depsides in Ramalina species has been confirmed.
Synthesis and Relative Stereochemistry of 2-Monohalo Ddt Pyrethroid Structures - 2-Halo-1-(4′-Ethoxyphenyl)Cyclopropane-1-Methanols and Cyclopropane-1-Carboxylic Acids and Esters
Authors: Johnson WMP , Holan G , Jarvis KE
Published: September 2010

This paper describes the essential features of the synthesis of a series of 2-monohalo DDT pyrethroid insecticides (8), as well as, the proof of the relative stereochemistry of substituents around the cyclopropane ring.
Mixing of a Carboxylate Stretching Vibration and Methylene Scissoring in Monosubstituted Acetate Ions. Major Effects of Counter Cation and Environment
Authors: Kang IPS , Spinner E
Published: September 2010

Infrared absorption spectra in the range 1500-1350 cm-1 (or lower) are reported for solid salts (XCH2CO2)nM where M is an alkali (n = 1) or alkaline earth metal (n = 2), and X = CH3, CN, F, Cl , Br or I, and also for aqueous XCH2CO2-. With X = CN, Cl , Br or I, when a doubly charged cation is replaced by a singly charged one of nearly the same mass, or a smaller one by a larger one in the same group in the periodic table, infrared intensity is redistributed from bands at higher frequencies to bands at lower frequencies. The carboxylate stretching vibration has a high infrared intensity, and normally its (intrinsic) frequency is lowered systematically by counter- cations in the above order, but in these ions it mixes strongly with methylene scissoring, the intrinsic frequency of which is only weakly environment-dependent. The intensity redistribution reflects a redistribution in carboxylate stretching character among the resultant composite vibrations. In propionate salts the situation is probably similar, but band overlaps often introduce uncertainty. In aqueous solution the lower of the two frequencies involved has the higher infrared intensity when X = CN, Cl , Br, I or CH3. For fluoroacetates, by contrast, the more intense band is that at the higher frequency, in water and in most solid salts; there is no systematic intensity redistribution as the cation is changed; the mixing of vibrations is more extensive and involved there.
Conformational Preference in CH3, CH2F and CF3 Compounds of 1st and 2nd Row Elements
Authors: Magnusson E
Published: September 2010

Energy changes and differences in geometries between the staggered and eclipsed conformations of methyl-, fluoromethyl - and trifluoromethyl - substituted compounds have been determined in a systematic ab initio study of compounds of first and second row elements. Geometry-optimized results at extended basis set level obtained on SiH3X, SiH2X-, PH3X+, PH2X, PHX-, SH2X+ and SHX species (X = CH3, CH2F, CF3) are compared with data on the corresponding first row compounds. The structural relaxation accompanying rotation in methyl compounds of second row elements is smaller than it is in compounds of the first row but for X = CF3 the geometrical changes are comparable. However, the relaxation contribution to energy is much smaller in the heavier compounds.
Synthesis of Benzo[D]Thieno[2,3-G]Azecine and Benzo[D][1]Benzothieno[2,3-G]Azecine Derivatives
Authors: Browne EJ
Published: September 2010

Derivatives of two new diannulated azecine systems have been prepared by ring degradation of precursor bases with cyanogen -bromide-induced
solvolysis. Reaction of a tetrahydro-5H-benzo[h] thieno [2,3,-a] quinolizine (5a) and a tetrahydro-7H-benzo[h][1] benzothieno [2,3-a] quinolizine (5b) with cyanogen bromide and magnesium oxide under solvolytic conditions yielded derivatives of a hexahydrobenzo [d] thieno [2,3-g] azecine (6a) and a hexahydrobenzo [d][1] benzothieno [2,3-g] azecine (6b), respectively. Functional group interconversions of these medium-ring systems were performed, including oxidations to cyclic ketones. The 5H-benzo[h] thieno [2,3-a] quinolizine and 7H-benzo[h] [l] benzothieno [2,3-a] quinolizine bases (5a) and (5b) are the first reported examples of these ring systems.
Reaction of 2-(6-Hydroxyspiro[4.5]Dec-6-Yl)-Alkanoic Acids With Aldehydes
Authors: Fujita T , Watanabe S , Sotoguchi T , Ogawa K , Sugahara K
Published: September 2010

The acid- catalysed reaction of aldehydes or ethyl vinyl ether with β- hydroxy acids containing a spiro ring is described. For example, 7,9- dioxadispiro [4.0.5.4]pentadecan-10-one was obtained in 90% yield from the reaction of (6-hydroxyspiro[4.5]dec-6-yl)acetic acid and 1,3,5- trioxan and 8-methyl-7,9-dioxadispiro[4.0.5.4]pentadecan-10-one was obtained in 72% yield from (6-hydroxyspiro[4.5]dec-6-yl)acetic acid and
ethyl vinyl ether.
The Structure of the Tetranuclear Cubane-Like Nickel(II) Xanthate Alkoxide [Ni(C2H5OCS2)-(C5H4NCH2O)]4 as Its Acetone Solvate, an Example of a Non-Reversible Inclusion Compound
Authors: Bizilj K , Hardin SG , Hoskins BF , Oliver PJ , Tiekink ERT , Winter G
Published: September 2010

The crystal structure of the acetone solvate of a mixed ligand tetranuclear nickel(II) complex involving the pyridine-2-methoxide ( pym ) and 0-ethylxanthate (exa) anions has been determined by X-ray diffraction methods. Crystals of [Ni (exa)( pym )]4.Me2CO are triclinic, space group Pī , a 13.825(2), b
15.606(3), c 12.288(2)Ǻ, α 101.16(2), β 101.38(1), γ 85.80(1)°, with Z 2; R and Rw were 0.056 and 0.057 respectively for 4,771 unique reflections for which I ≥ 3σ(I). The structure consists of tetranuclear cubane -like clusters with four nickel and four oxygen atoms arranged at alternate corners of a distorted cube. The discrete molecules of occluded acetone are located in cavities defined by the [Ni( exa )( pym )]4 units.
Synthesis of Symmetrical Poly(pyridin-2-yl)Ethane Ligands
Authors: Canty AJ , Minchin NJ
Published: September 2010

Reaction of lithium
derivatives of pyridin-2-ylmethanes, (C5H4N)CRR′- Li+, with mercury(II) iodide results in precipitation of mercury, and formation of symmetrical poly(pyridin-2-yl)ethanes [(C5H4N)CRR′]2
(R = H, R = Ph; R = Me, R′ = Ph; R = R′ = Me; R = C5H4N, R′ = H; R = C5H4N, R′ = Me). For [(C5H4N)CRPh]2 (R = H, Me) mixtures of the meso and racemic diastereoisomers were found. Two of the products, [(C5H4N)CHPh]2 and [(C5H4N)2CH]2, were obtained in high yield, and readily form palladium(II) acetate complexes, Pd(O2CMe)2{rac-[(C5H4N)CHPh]2} and [Pd(O2CMe)2]2[(C5H4N)2CH]2. The synthesis of 2-(1-phenylethyl)pyridine and a convenient route to bis(pyridin-2-yl)methane are described.
Structures of 2 Vanadium(V) Complexes With Tridentate Ligands
Authors: Diamantis AA , Frederiksen JM , Salam MA , Snow MR , Tiekink ERT
Published: September 2010

The crystal structures of two vanadium(v) complexes, VOL(OCH2CH3)(1) and (VOL)2O (2), where L is the dinegative , tridentate ligand 4- phenylbutane-2,4-dione benzoylhydrazonato (2-),
were determined by X-ray diffraction methods. Crystals of (1) are monoclinic, space group P21/n, a 11.064(4), b 7.565(1), c 21.786(5) Ǻ and β 95.93(2)° and Z 4; those of (2) are also monoclinic, C2/ c, with unit cell dimensions a 18.287(3), b 14.991(2), c 11.643(2)Ǻ, β 92.85(2)° for Z 4. The structures were refined by full-matrix least-squares methods to
final R 0.036 for 1801 reflections with I ≥ 2.5σ(I) for (1), and R 0.061 for 1272 reflections with I ≥ 2.5σ(I) for (2). The coordination environment of the vanadium atom in both structures is a tetragonal pyramid with the oxo ligand occupying the apical positon.
Cluster Chemistry. XLIII. Sulfur-Carbon Bond Cleavage Reactions in the Hydrogenation of Some Sulfur-Containing Ruthenium Carbonyl Cluster Complexes: X-Ray Structure of Ru3(μ-H)2(μ3-S)(μ-(Z)-Ph2PCH=CHPPH2)(CO)7
Authors: Bruce MI , Shawkataly OB , Snow MR , Tiekink ERT
Published: September 2010

Reactions between Ru3(μ-H)(μ3-SBut)(CO)9 and dppm have given Ru3(μ-H)(μn- SBut)(μ-dppm)(CO)10-n(n = 2,3); hydrogenation of all three complexes resulted in S-C bond cleavage and formation of Ru3(μ-H)2(μ3-S)(CO)7(L2) [L2 = (CO)2, μ-dppm]. Facile substitution of 2CO in Ru3(μ-H)2(μ3-S)(CO)9 by dppm, dpam or ebdp (L2), catalysed by Na+[Ph2CO]- or [ppn][OAc], gave Ru3(μ-H)2(μ3-S)(μ-L2)(CO)7, in which the bis-tertiary phosphine (or arsine) bridges an edge of the Ru3 triangle, with the P (or As) atoms occupying equatorial positions. In the case of L2 = ebdp, this edge is also bridged by H, as shown by a single-crystal X-ray structure determination. Crystals of the title compound are mcnoclinic, space group P21/n, with unit cell parameters a 13.454(3), b 17.748(2), c 14.706(2) Ǻ, and β 94.50(1)°. The structure was refined by a full-matrix least-squares method; at convergence R and Rw were 0.036 and 0.038, respectively, for 4729 reflections with I ≥ 3.0σ(I).
Synthesis and Spectroscopic Studies of Triorganotin(IV) Complexes Involving Diorganophosphino and Diorganophosphino-N-Phenyl(Thioformamido) Ligands - the Crystal and Molecular-Structure of Dicyclohexylphosphino-N-Phenyl(Thioformamido)-Triphenyltin, Ph3Sn[(c-C6H11)2PC(S)NPh]
Authors: Dakternieks D , Hoskins BF , Rolls CL
Published: September 2010

Phosphorus-31 and tin-119 n.m.r . data imply that the tin complexes R3Sn[R1,PC(S) NPh ] (where R = Ph, Me, Bu; R′ = Ph) exist in solution as both sulfur-bonded and nitrogen-bonded isomers. When R′ = c-C6H11, only one isomer is observed. n.m.r . data are also reported for the series R3SnPR′2. Both series of complexes contain four-coordinate tin in dichloromethane solution. The crystal and molecular structure of the tin(IV) complex Ph3Sn[(c-C6H11)2PC(S) NPh ] has been determined by single-crystal X-ray diffraction techniques. The crystals are triclinic, space group Pī , a 10.689(2), b 11.066(1), c 16.315(3) Ǻ, α 101.94(1), β 104.85(1) and γ 105.72(1)° with Z 2; R and Rw were 0.032 and 0.030 respectively for 5169 unique reflections with I ≥ 2σ(I). The structure has two independent centrosymmetrically related mononuclear molecules within the unit cell. The tin atom is in a tetrahedral environment formed by three phenylic carbon atoms and a sulfur atom from the [(c- C6H11)2PC(S) NPh ]- ligand.
Oxidative Addition of Functionalized Alkyl-Halides to Iridium(I) Complexes IrCl(Co)L2 (L = PMe2Ph2>, IrCl(Co)PMe3)
Authors: Bennett MA , Crisp GT
Published: September 2010

Iridium(I) complexes IrCl (CO)L2 (L = PMePh2, PMe2Ph, PMe3) oxidatively add alkyl bromides RBr bearing electron-withdrawing substituents on the α-carbon atom (R = CH2CO2Et,CH3CHCO2Et,CH3CHCOCH3,C2H5CHNO2) to give octahedrally coordinated alkyliridium (III) complexes IrBrClR (CO)L2, for which 1H and 31P n.m.r . data are reported. In the secondary alkyls, the mutually trans tertiary phosphine ligands are inequivalent, consequently the P-Me resonance is not the usual 1 : 2 : 1 'virtual' triplet. In some cases the pattern is a doublet or a doublet of doublets, similar to that expected for mutually cis tertiary phosphine ligands . In contrast to simple s- alkyliridium (III) complexes, the functionalized s-alkyls do not isomerize under any conditions to the corresponding n-alkyls, and the reverse process does not occur for n-alkyls such as IrBrCl (CH2CH2CO2Et)(CO)(PMe3)2 and IrClI (CH2CH2CN)(CO)(PMe3)2. Diiodomethane and chloroiodomethane readily add to IrCl (CO)L2 to give haloalkyliridium (III) complexes IrClI (CH2Y)(CO)L2(Y = Cl , I). These contain mutually trans tertiary phosphine ligands , although in the case of L = PMe2Ph unstable cis - isomers can be detected. Attempts to form complexes containing Ir - CHBrCH3 or Ir -CH(OC2H5)CH3 by addition of CH3CHBr2 or CH3CHClOC2H5 to IrCl (CO)(PMe3)2 gave only IrBr2Cl(CO)(PMe3)2 and IrHCl2(CO)(PMe3)2, respectively.
Spectroscopic Studies on Some Pyridine and Morpholine Adducts of (meso-Tetraphenylporphyrin)Chromium(III) Chloride
Authors: Roe SP , Hill JO , Magee RJ
Published: September 2010

Infrared, electronic and X-ray photoelectron spectroscopic data are reported for a series of ( meso-tetraphenylporphyrin )chromium(III) chloride adducts: Cr( tpp ) ClL , where L = pyridine, 2-picoline, 4- picoline , 2,6-lutidine, 4-cyanopyridine and morpholine . The data are interpreted in terms of increased symmetry of the porphinato moiety upon metallation and changes to the metal electronic environment resulting from the inductive and steric effects of the axial base- ligand L. A correlation is shown to exist between the EF/b(Cr 2p3/2) binding energy and the band I electronic transition energy for these complexes, which quantifies the influence of the base- ligand L on the electronic environment of the coordinated metal.
Applications of Cd N.M.R. to Polycadmium Complexes. IV. Reactions of [Cd10(SCH2CH2OH)16]4+ With Chloride Ion, and the Crystal and Molecular Structure of Hexadeca(2-Hydroxyethanethiolato)-Tetrachloro-Decacadmium [Cd10(SCH2CH2OH)16Cl4]
Authors: Dance IG , Garbutt RG , Craig DC
Published: September 2010

Reaction of [Cd10(SCH2CH2OH)16]4+ (ClO4-)(1) with chloride ion in dimethylformamide produces Cd10(SCH2CH2OH)16Cl4 (4). Crystalline (4) [P bcn, a 14.802(3), b 24.950(5), c 20.891(4) Ǻ, 2032 observed data (Mo Kα ),
R 0.047] contains molecular aggregates (symmetry exactly 2, approximately 4) in
which the Cd10S16 core is similar to that of (1), but
which differ in that eight instead of sixteen of the ligand
hydroxy functions are coordinated in (4). Six inner Cdi atoms occur in pseudo- octahedral array, four with Cdi (SR)4(OH) coordination involving chelation of μ3-SCH2CH2OH [as in (1)], while the other two are six- coordinate Cdi (SR)4(OH)2 in an unusual stereochemistry which arises by partial transverse addition of a pair of hydroxy functions across an edge of the tetrahedral Cdi (SR)4 site of (1). The four CdO atoms of (4) each possess tetrahedral (SR)3CdOCl coordination. 113Cd n.m.r . spectra of mixtures of (1) and Cl - in dimethylformamide reveal ( i ) the progress of the change (1)→(4) and correlation of chemical shifts with the five different cadmium sites; (ii) the rapid interchanges of Cdi sites in (4) and between (4) and (1), interchanges which are slowed to <104 s-1 at <c. 230 K; (iii) modifications of the dynamics of Cdi site interchange caused by relatively small proportions of Cl -; and (iv) interconversion of CdO sites between (4) and (1).
Chiral Induction in the Methylation of N-Ethoxycarbonylmethyl Sulfoximines
Authors: Hambley TW , Hambley TW , Raguse B , Raguse B , Ridley DD , Ridley DD
Published: September 2010

Chiral inductions in the C- methylations of four optically active N-ethoxycarbonylmethyl-S-p-tolylsulfoximines were explored by using the reagents lithium diisopropylamide (in tetrahydrofuran at -78°) then methyl iodide. When the fourth substituent at sulfur was a methyl group, complex mixtures of products were formed. However, when the fourth substituent was an aryl group, moderate yields of methylated compounds were formed and the ratio of diastereomers produced were 50 : 50 ( Ar = phenyl), 76 : 24 ( Ar = o- methoxyphenyl ) and 100 : 0 [ Ar = o-(2-methoxyethoxy)phenyl]. The diastereoselectivities are accounted for by intramolecular chelation of the aryl-oxygen substituents with the intermediate lithiated carbanion. The structure and absolute configuration where Ar = o-(2-methoxyethoxy )phenyl were confirmed by X-ray crystallographic methods. Space group P 212121, orthorhombic, a 10.2500(7), b 13.281(2), c 16.526(2) Ǻ; final R 0.064 (on 924F). The configuration at the sulfur atom is (S) and that induced at the carbon atom is (R).
Aluminum(III)-Citrate Complexes: a Potentiometric and 13C N.M.R.-Study
Authors: Gregor JE , Powell HKJ
Published: September 2010

The equilibrium reactions of citrate ion with protons and aluminium(III) have been studied by potentiometric titration in aqueous solution, I 0.10 M KCl, 25°C. The protonation constants for citrate, log Ki, corrected for K+-citrate ion pairing, were determined as 5.90�0.02, 4.35�0.01 and 2.91�0.02, i = 1-3 respectively. The model which gave the best fit to experimental data for the aluminium-citrate equilibrium system (TL/TM > 5.3) included AlHL + ( logβ 11.02�0.02), AlL (8.35�0.23), AlL23- (13.40�0.35), Al(HL)L2- (17.36�0.11), AlL2H-14-[ pK (AlL23-)6.07�0.24] and Al(LH-1)25- [ pK (AlL2H-14-) 7.09�0.08]. 13C n.m.r.data established that ligand exchange in the aluminium(III) complexes is slow on the n.m.r . time scale. The spectra were consistent with deprotonation
of the coordinated C(2)-OH group commencing between pH 5 and 6, corresponding to formation of the species designated AlL2H-14- and Al(LH-1)25-. The broad structure of the- CH2-, -COOH (central) and -COOH (terminal) resonances for coordinated citrate was indicative of coordination isomers and/or the presence of both mono and bis complexes.
The Structures of Bis(O-Benzylxanthato)Nickel(II) and the Benzene Clathrate of Its 1,10-Phenanthroline Adduct
Authors: Edwards AJ , Hoskins BF , Winter G
Published: September 2010

The crystal and molecular structures of bis (O- benzylxanthato )nickel(II), Ni( bzxa )2, and the benzene clathrate of its 1,10-phenanthroline adduct, Ni( bzxa )2( phen ).C6H6, are reported. Crystals of Ni( bzxa )2 are orthorhombic, with the space group P bca. There are four molecules per unit cell, which has dimensions a 6.961(1), b 35.008(8), c 7.277(2)Ǻ. The refinement converged with R 0.031 and Rw 0.037 after use of 1732 independent reflections for which I ≥ 2σ(I). Asymmetry of the nickel-sulfur bonds is observed. The adduct crystallizes in the space group C2/c. There are four molecules each of the adduct and benzene per unit cell, which has dimensions a 7.133(3), b 18.196(5), c 24.282(5)Ǻ, β 97.01(2)°. The refinement converged with R 0.064 and Rw 0.052 after use of 1123 independent reflections for which I ≥ 2σ(I). The packing clearly indicates that this host-guest compound is of the clathrate type.
Organoamidometallics. I. Syntheses of [N,N′-Bis(Polyfluorophenyl)Ethane-1,2-Diaminato(2-)]Platinum(II) Complexes by Decarboxylation
Authors: Buxton DP , Deacon GB , Gatehouse BM , Grayson IL , Thomson RJ , Black DS
Published: September 2010

Reaction of PtCl2(en) (en = ethane-1,2-diamine) with thallous pentafluorobenzoate in hot pyridine ( py ) or 4-methylpyridine ( mepy ) yields the [N,N′- bis (2,3,5,6-tetrafluorophenyl)ethane-1,2-diaminato(2-)]platinum(II) complexes, Pt[N(p-HC6F4)CH2]2( py )2 (1a) and Pt[N(p- HC6F4)CH2]2( mepy )2 (1b). The route to (1a) is considered to involve formation of [Pt(en)( py )2](O2CC6F5)2 (2), decarboxylation of (2) into Pt(NHCH2)2( py )2 (1c) and pentafluorobenzene, and nucleophilic attack of (1c) on C6F5H. Complex (1a) has also been prepared by decarboxylation of (2), reaction of PtI2(en) and TlO2CC6F5, and reaction of PtCl2(en), C6F5H, and TlO2CC6F4H-p in boiling pyridine. From reaction of PtCl2(en), TlO2CC6F4H-p, and the appropriate polyfluorobenzene (RF) in boiling pyridine or 4-methylpyridine, the organoamidoplatinum compounds Pt(NRCH2)2L2(R = C6F5, p-MeC6F4, p-ClC6F4, p-BrC6F4, p-IC6F4, 2,3,5-F3C6H2, or p-C6F5C6F4, L = py and R = C6F5, L = mepy ) have been prepared. Analogous reactions of PtCl2( pn )( pn = propane-1,3-diamine) give the complexes Pt[NR(CH2)3NR]( py )2 (R = C6F5 or p-HC6F4). Spectroscopic evidence for the structures is discussed. The polyfluorophenyl groups confer stability to water on ethane-1,2-diaminato(2-)platinum(II) complexes, and this is attributable to delocalization of non-bonded lone pairs from the amido nitrogens into the polyfluorophenyl rings.
Redox Properties of Macrotricyclic Hexaamine Cobalt(III) Complexes
Authors: Hammershoi A , Lawrance GA , Sargeson AM
Published: September 2010

Electrochemical properties of the macrocyclic hexaamine cobalt(III) complex [Co( taetacn )]3+ and its macrotricyclic derivatives [Co( azasartacn )]3+, [Co( nosartacn )]3+, [Co( amsartacn )]3+, and [Co( amsartacnH )]4+ in water, acetonitrile and acetone are reported and compared with those of macrobicyclic analogues. The results show that the tricyclic cage complexes are reduced somewhat more readily than their bicyclic equivalents, implying that the cavity sizes for the tricyclic systems are somewhat larger.
Steric Effects. Inversion of 4,5-Disubstituted 9,10-Dihydrophenanthrenes
Authors: Cosmo R , Sternhell S
Published: September 2010

Six 4,5-di-X-9,l0-dihydrophenanthrenes (X = H, F, OCH3, Cl, CH3, CF3) were synthesized and their inversion rates were investigated by n.m.r., spectroscopy. The barriers to inversion at a standard temperature (∆G‡;340) ranged from <25 to >120 kJ mol-l and showed good correlation with the van der Waals radii of the interacting substituents at C4 and C5 and with the previously proposed 'apparent overlap' parameter.
Campnosperma Exudates. The Optically Active Long Chain 5-Hydroxycyclohex-2-Enones and Long-Chain Bicyclo[3.3.1]Nonane-3,7-Diones
Authors: Johns SR , Lamberton JA , Morton TC , Suares H , Willing RI
Published: September 2010

Re-examination of the optically active long-chain 5-hydroxycyclohex-2-enones of Campnosperma species has confirmed the former structural assignments, except that in Tigaso oil both the 5- hydroxycyclohex-2-enones and the phenolic components contain a significant (35-40%) proportion of compounds with di-unsaturation in the C19-chain. Further study has been made of the conversion of (-)-endo-4-hexadecyl-l-hydroxybicyclo[3.3.l]nonane-3,7-dione (10) into a mixture of an optically inactive and optically active β- diketones. The major product from this reaction is (�)-5-(1-acetylheptadecy1)cyclohexane-1,3-dione (1l), which on methylation with diazomethane gives a mixture of two diastereoisomeric Omethyl ethers. These undergo cyclization to give a mixture of two epimeric 4-hexadecyl-l-methoxybicyclo[3.3.l]nonane-3,7-diones, (16) and (17), but reduction of the enol ethers followed by cyclization leads to an epimeric mixture of 4 hexadecylbicyclo [3.3.l]nonane-3,7-dion, (21) and (22). A detailed n.m.r. study of the bicyclo[3.3.l]nonane-3,7-diones, (10), (16), (17), (21), (22), (27) and (28), indicates that all have a chair-chair conformation, and also shows which of these compounds have an equatorial substituent, (10), (16), (21) and (27), and which an axial, (17), (22) and (28), at C4. Reduction of the bicyclo[3.3.1]nonane-3,7-diones with sodium borohydride gives oxaadamantane derivatives, and reduction of one diastereoisomeric β- diketone Omethyl ether gives a high yield of (�)-endo-4-hexadecyl-exo-3-methyl-2-oxabicyclo[3.3.l]nonane-7-one (25), the structure of which has been fully derived from n.m.r. study.
Determination of the Rates of Ring-Closure of Oxygen-Containing Analogs of Hex-5-Enyl Radical by Kinetic Electron Spin Resonance Spectroscopy
Authors: Beckwith ALJ , Glover SA
Published: September 2010

The hex-5-enyl (1), 3-oxahex-5-enyl (6), 2-oxahex-5-enyl (9) and 2,2-dimethylbut-3- enoyloxymethyl (13) radicals have been generated by interaction of the corresponding bromides with trialkyltin or trialkylgermanium radicals, and their rate constants and activation parameters for cyclization have been determined by kinetic e.s.r . spectroscopy. The 3-oxa species (6) undergo 1,5-ring closure more rapidly than does hex-5-enyl radical (1) because of favourable stereoelectronic factors. Spectral evidence has been obtained for restricted rotation about the O-CH2* bond in the 2-oxa radical (9) as a consequence of which its ring closure is relatively slow. Similarly, 1,5-ring closure of the ester derived radical (13) is slow because of unfavourable conformational effects arising from restricted rotation about the CO-O bond. The radical (22) formed from allyl bromoacetate does not undergo ring closure. Spectral data have been obtained for various radicals (16), (19), (23), (24) formed by intermolecular addition.
Experiments Directed Towards the Synthesis of Anthracyclinones. XIII. Ozonolyses of Anthrafurans
Authors: Cambie RC , Larsen DS , Rutledge PS , Woodgate PD
Published: September 2010

Ozonolyses of anthrafurans have been studied as a possible step in a route to anthracyclinones.
Nucleophilic Displacement in Polyhalogenoaromatic Compounds. XIII. Polyfluoroarene Systems
Authors: Atwal RK , Bolton R
Published: September 2010

Rate coefficients are reported for the methoxydefluorination of decafluoro-biphenyl and -phen-anthrene, of octafluoro-biphenylene, -naphthalene, -acenaphthylene, and -toluene, of 4H- heptafluorotoluene and the 4-bromo and 4-phenyl analogues, and of tetradecafluoro-4,4'- dimethylbiphenyl in methanol at 298 K. These rates are compared with theoretically calculated reactivities; none give perfect correlation. The orientation of nucleophilic attack upon polyfluorinated aromatic systems may be simply understood by considering each aromatic ring to act as a single entity and neglecting the effects of the carbon substituents, so that the orientation of attack of each benzene ring is the same as that of the corresponding polyfluorobenzene.
Detection of Non-Conjugative Interactions in Rigid Cyclic Molecules by Using Carbon-13 N.M.R. Shift Values
Authors: Bishop R , Lee GH
Published: September 2010

In previous work, interaction between formally unconjugated unsaturated groups was detected by comparing the 13C n.m.r. shift values of the sp2 atoms of difunctional compounds with those of the corresponding monofunctional compounds. This procedure has now been used to investigate possible interactive effects in a range of rigid alicyclic systems where steric and conformational factors cannot be involved, namely, the 2,6-disubstituted adamantane (6), 4,8-disubstituted 2-thiaadamantane (7), 2,6-disubstituted noradamantane (8), and 2,5-disubstituted norbornane (9) systems. In each case interaction was detected between the unsaturated groups of the non-conjugated dimethylene, methylene ketone, and diketone derivatives of these ring systems. The nature of this effect is under further investigation.
Cation-Exchange Chromatography of Hexaminechromium(III)-Type Complexes on SP-Sephadex
Authors: Searle GH
Published: September 2010

The chromatographic elutions (with the eluents Na3PO4, Na2-(+)-tart, Na2SO4) of the following pairs of analogous hexamine-type complexes of chromium(III) and cobalt(III) on SP-Sephadex have been measured quantitatively (as Rx values relative to [Co(en)3]3+) and compared: [M(NH3)6]3+,M(en)3]3+, [M( tn )3]3+, s- fac and mer [M( dien )2]3+, and mer -[M( dpt )2]3+. Conclusions are: ( i ) The CrIII complexes elute more slowly and with less discrimination than their CoIII analogues. (ii) There is a generally regular correlation between the elutions of analogous CrIII and CoIII complexes, so that deductions of geometric configurations of new CrIII complexes from chromatographic comparisons should be possible. Two small reversals of elution order of complexes with different eluents are observed.
Lichens and Fungi. XVIII. Extractives From Pseudocyphellaria rubella
Authors: Corbett RE , Cong ANT , Holland PT , Wilkins AL
Published: September 2010

Twenty lupane triterpenoids including five (20RS)- epimeric pairs have been isolated from the chloroform extractives of the lichen Pseudocyphellaria rubella. The utility of g.c.-m.s . procedures in the structural elucidation of the extractives, some of which were complex mixtures is discussed.
Synthesis of ent-Kaurene From a Naturally Occurring Precursor
Authors: Hogg RW , Knox JR
Published: September 2010

ent - Kaurene (1) has been synthesized from a naturally occurring precursor, ent- kaurane - 17,19-diol (3a). Selective deoxygenation at C 19 of the diol was achieved after the C17 hydroxyl was protected as the triphenylmethyl ether. ent- Kaurene was then prepared by way of an elimination sequence at C17.
Variable-Temperature Ultraviolet Photoelectron-Spectroscopy of the Keto-Enol Tautomers of Pentane-2,4-Dione
Authors: Hush NS , Livett MK , Peel JB , Willett GD
Published: September 2010

The HeI photoelectron spectra of pentane-2,4-dione measured at various temperatures have been subjected to a spectrum-stripping technique to enable isolation of the complete HeI photoelectron spectra of the keto and enol tautomers. The resulting spectrum-stripping coefficients allow evaluation of the enolization equilibrium constant at each temperature and subsequently the enthalpy of enolization. Interpretation of the photoelectron spectra is achieved with the use of ab initio molecular orbital calculations. Photoionization of non-bonding oxygen, and π -type electrons, contribute to the low ionization energy region of the spectrum, with a πCC < no- <πCO ordering for the enol tautpmer , and no- < no+ < πCO+ for the keto tautomer . Because of different electronic relaxation effects, ∆SCF calculations are required to predict correctly the observed πCC/no- spacing for the enol tautomer.
Carbon Dioxide Formation From Organic Solutes in Aqueous Suspensions of Ultraviolet-Irradiated TiO2. Effect of Solute Concentration
Authors: Matthews RW
Published: September 2010

The oxidation of a number of aromatic compounds to carbon dioxide by exposure to near U.V. light in aqueous titanium dioxide suspensions has been studied as a function of the solute concentration. In most, the dependence of the rate of CO2 formation follows the simple Langmuir expression:R(CO2)=k1k2[s]/(1+k1[s])The rate is essentially independent of concentration above 200 �M and becomes progressively more dependent on the concentration as it decreases. Changes in the mineralization rate are most clearly reflected in k2, the parameter determined by the limiting rate at high concentrations. A consequence of the dependence is that total mineralization is strictly never achieved but is approached asymptotically at extended illumination times. The expression and parameters are given which enable the prediction of the extent of mineralization over a wide range of concentrations. The solutes studied were benzene, benzoic acid, benzoate ion, salicylate ion, phenol, chlorobenzene , aniline, anilinium ion, nitrobenzene, chloroform and formic acid. It was confirmed that pH and oxygen concentration affect the rate of carbon dioxide formation but, in the photochemical reactor used, the rate was not significantly affected by the amount of TiO2 suspended for loadings from 0.05 to 0.40 g per 400 ml.
Preparation of Hydrido η6-Hexamethylbenzene Complexes of Ruthenium(II) Containing Various Tertiary Phosphines. Displacement of Coordinated Triphenylarsine or Triphenylstibine From RuHCl (η6-C6Me6)L (L = AsPh3, SbPh3)
Authors: Bennett MA , Latten J
Published: September 2010

Twelve new complexes in the series RuHCl (η6-C6Me6)L [L = PBut2Me (5), PBut2Et (6), PBut2Pr (7), PMe3 (8), PMe2Ph (9), PMePh2 (10), PEtPh2 (ll), PPh2Pr (12), P( OPh )3, (13), P(OMe )3 (14), PEt3 (15), or PPh2(C6H4Me-o) (16)] have been prepared by one of three methods: 1, heating [RuCl2(η6-C6Me6)]2 with an excess of L and of anhydrous Na2CO3 in propan-2-ol (5)-(7); 2, heating pre-formed RuCl2(η6-C6Me6)L with an excess of Na2CO3 in propan-2-ol (8), (9), (11); 3, displacement of AsPh3 or SbPh3 by L from RuHCl (η6-C6Me6) L (L= AsPh3, SbPh3) (10)-(16). The new dihydrido complexes RuH2(η6-C6Me6)L (17)-(19) have been made by NaBH4 reduction of either RuCl2(η6C6Me6)L [L = PMe2Ph (17), PButMe2 (18) or of RuHCl (η6 -C6Me6)L [L = Pbut2Et (19)]. Under the conditions of method 2, RuCl2(η6-C6Me6)(PPh2(C6H4Me-o)) (4) undergoes deprotonation at the o- tolyl methyl group to give the cyclometallated complex RuCl (CH2C6H4PPh2-o)( η6-C6Me6) (20).
The Stereochemistry of Organometallic Compounds. XXVIII. The Nickel-Catalyzed Addition of Hydrogen Cyanide to Aliphatic Dienes
Authors: Campi EM , Elmes PS , Jackson WR , Lovel CG , Probert MKS
Published: September 2010

Reaction of hydrogen cyanide with a wide range of aliphatic dienes in the presence of nickel(0) catalysts leads to rearrangement of the diene and formation of β,γ -unsaturated nitriles in moderate to very high yields. The mechanism of reaction is discussed in terms of π-allyl-nickel intermediates.
The Structure of Triketones in the Solid-State. The Crystal-Structure of 1,5-Diphenylpentane-1,3,5-Trione
Authors: Ceaolivares R , Rodriguez I , Rosales MJ , Toscano RA
Published: September 2010

The crystal structure of 1,5-diphenylpentane-1,3,5-trione was determined, C17F14O3, M266.14, orthorhombic, space group Pbca , a 8.602(2), b 10.398(2), c 30.010(10) �, V 2684 14 �3, p(ca1c) 1.317g cm-3, Z 8, F(000) 1120, �(Cu Ka) 6.91 cm-l. The structure was solved by direct methods and refined to a final R value of 0.040 for 1539 unique reflections. The molecules of the compound are found in the dienol form.
Metal (Phenylthio)Alkanoic Acid Interactions. VII. The Crystal Structures of catena-[(Phenylthio)ethanoatosilver(I)] and Tetrakis-μ-[2-(2-chlorophenylthio)-2-Methyl-Propanoato-O,O']-bis[aquacopper(II)]
Authors: Chan WH , Mak TCW , Yip WH , Kennard CHL , Smith G , Oreilly EJ
Published: September 2010

Metal complexes of two (phenylthio) alkanoic acids have been prepared and their structures determined by X-ray diffraction. catena-[( Phenylthio ) ethanoatosilver (1)] (1) forms crystals which are orthorhombic, space group Pccn, Z 8 and a 26.772(8), b 10.479(3) c 6.007(1) �. The polymer structure consists of a distorted trigonal pyramidal AgO3S repeating unit with coordination in the trigonal plane by a bidentate chelate thioethanoate group [Ag-O, 2.508(3); Ag-S, 2.513(2) �]. The third position in the plane and the axial position are occupied by bridging carboxylate oxygens [Ag-0, 2.454(3), 2.230(4) �], giving the two-dimensional structure. Complex (2) is a tetracarboxylate bridged dimer of the copper(11) ethanoate hydrate type, with a Cu-Cu separation of 2.624(2) � and Cu-OH2 (axial) distances of 2.155(7) and 2.182(6) �. Crystals are triclinic, space group PI with two dimers in a cell of dimensions a 7.340(2), b 14.863(5), c 22.963(8) �; α 104.33(2), β98.18(2), γ 102.18(2)�. Final residuals for (1) and (2) were 0.045 and 0.051 for 1688 and 3467 observed reflections respectively.
Molten Potassium Pyrosulfate: Reactions of Lanthanum Metal and Six of Its Compounds
Authors: Mineely PJ , Tariq SA
Published: September 2010

The reactions of lanthanum metal, La2O3, La(OH)3, La(NO3)3.6H2O, La2(CO3)3.3H2O, LaCl3 and LaCl3.7H2O with molten K2S2O7 were studied. The metal reacted with K2S2O7 to produce La2(SO4)3, K2SO4 and SO2. Lanthanum(III) oxide was converted into La2(SO4)3, as were La(OH)3, La(NO3)3.6H2O, La2(CO3)3.3H2O, LaCl3 and LaCl3.7H2O but with the evolution of H2O, NO2 + O2 + H2O, CO2 + H2O, Cl2 + SO2 + S and Cl2 + SO2 + H2O + HCl respectively. K2S2O7 was converted into K2SO4 in the reactions. Reaction pathways have been suggested to explain the final products. The temperatures and stoichiometries of the reactions have been established.
A New Sesterterpene Tetronic Acid From an Australian Sponge, Ircinia sp
Authors: Capon RJ , Macleod JK
Published: September 2010

A new sesterterpene tetronic acid* (2), exhibiting antimicrobial activity, has been isolated from an Australian Ircinia species. The structure elucidation was based on detailed spectroscopic analysis of (2), its acetate (3), and two methylated derivatives (4) and (5).
Ab initio Studies of Hydrazines: Equilibrium Structures of 1,1-Dimethylhydrazine and Transition Structures Connecting Them
Authors: Riggs NV , Radom L
Published: September 2010

Optimization of the geometries of various stationary structures of 1,1-dimethylhydrazine has been carried out with the 3-21G and 3-21G(N*) basis sets, and the energies of each of the latter optimized structures have been evaluated with the 6.31G* basis set. The gauche form with a (mean) internal rotational angle near 80� (hydrazine, approx. 90�) is the lowest-energy form. After zero-point vibrational -energy corrections, the anti form lies in a shallow well 14kJ mol-1 higher on the potential-energy surface for internal rotation, and the transition structure connecting them lies approx. 1 kJ mol-1 higher still. The anti form is thus a true equilibrium species, unlike the case for hydrazine, but constitutes less than 0.5% of the molecules present at room temperature. It is estimated to have a half-life of less than 10 ps , so its observation by present physical methods may prove to be difficult. The barrier to internal rotation via the syn form (41kJ mol-1) coincides with that for hydrazine. gem-Dimethyl substitution in hydrazine leads to a small rise (1-2 kJ mol-1) in the barrier to inversion at the unsubstituted nitrogen atom, but to an unexpectedly high (by 8-9 kJ mol-1) calculated barrier to inversion at the substituted centre, whether the result be referred to the barrier in hydrazine or to that in dimethylamine. Calculated NH stretching frequencies for the gauche form show a spacing much larger than that for 'simple' primary amines, as is found experimentally.
The Isolation and Synthesis of the Lichen Depside 4-O-Demethylmicrophyllinic Acid
Authors: Elix JA , Jayanthi VK
Published: September 2010

The depside 4-O-demethylmicrophyllinic acid (1) {4-[2,4-dihydroxy-6-(2-oxoheptyl) benzoyloxy ]-2-hydroxy-6-(2-oxohepty1)benzoic acid} has been isolated from a lichen for the first time. The structure of this compound and microphyllinic acid (2) were verified by unambiguous synthesis.
Crystal-Structures of Three Long, Rigid, Norbornylogous Compounds of Relevance to Distance-Dependence Studies of Long-Range Intramolecular Electron-Transfer Processes
Authors: Craig DC , Paddonrow MN
Published: September 2010

Results of previous studies revealed that photoinduced intramolecular electron transfer between the dimethoxynaphthalene donor and dicyanomethylene acceptor groups in the series of rigid alicyclic compounds (2a)-(6a) is extremely rapid. As the first step towards determining the distance dependence of the rate of photoinduced intramolecular electron transfer in these molecules, crystal structures of (3a), (4b) and (5b), have been measured. The edge-to-edge distance between the two chromophores in (3a), (4b) and (5b) is 6.8, 9.4, and 11.5 � respectively. The estimated centre-to-centre separation between the chromophores in (2a)-(6a) ranges from c. 7.1 � in (2a) to c. 14.9 � in (6a). From these results, dipole moments of the charge-separated states of (2a)-(6a), following photoinduced intramolecular electron transfer, could be estimated. These predicted values were in excellent agreement with those determined experimentally by using the time-resolved microwave conductivity technique. An interesting structural feature of (3a), (4b) and (5b) is the pronounced curvature of the molecular backbone in
these molecules. It is predicted that approximately 24 linearly fused norbornyl and bicyclo[2.2.0] units would complete a circle, forming a member of a novel class of macrocycles, tentatively called dogcollaranes.
Constituents of the Zingiberaceae. XI. Structures of (+)-(1R,2S,3R,4S)-2-Benzoyloxymethylcyclohex-5-ene-1,2,3,4-tetrol 4-benzoate [(+)-Zeylenol] and (+)-(1R,2R,4R,5S,6R,7R)-4-Benzoyloxymethyl-3,8-dioxatricyclo-[5.1.0.02,4]octane-5,6-diol 5-Acetate 6-Benzoate (Boesenboxide) Isolated From a New Boesenbergia Species
Authors: Tuntiwachwuttikul P , Pancharoen O , Bubb WA , Hambley TW , Taylor WC , Reutrakul V
Published: September 2010

A new Boesenbergia species ( Zingiberaceae ) has been found to contain (+)-(1R,2S,3R,4S)-2-benzoyloxymethylcyclohex-5-ene-1,2,3,4-tetrol 4-benzoate [(+)- zeylenol ] (2)and the crotepoxide -related substance, (+)-(1R,2R,4R,5S,6R,7R)-4-benzoyloxymethy1-3,8-Dioxatricyclo [5.1.0.02,4]octane-5,6-diol 5-acetate 6-benzoate ( boesenboxide ) (8). The structure (8) was determined by spectroscopic, chemical, and X-ray crystallographic studies. Boesenboxide forms monoclinic crystals P21, a 12.722(2), b 5.23O(l), c 16.139(3) �, β 106. 57(l)�; the crystal structure was refined to a residual of 0.029 for 1281 independent observed reflections.
Synthesis and Identification of ω-Phenylalkylcatechols in Burmese Lac
Authors: Jefferson A , Sargent MV , Wangchareontrakul S
Published: September 2010

The presence of 3-(10′-phenyldecyl)-(2) (2%), 3-(12′-phenyldodecyl)- (3) (6%), 4-(10′-phenyldecyl)-(4) (0.3%) and 4-(12′-phenyldodecyl)- benzene-1,2-diol (5) (0.3%) in Burmese lac , the sap of Melanorrhoea usitata Wall has been confirmed by the synthesis of these compounds and a comparison of the gas chromatographic retention times and the mass spectral characteristics of their bis-O-( trimethylsilyl ) derivatives with the derivatives of the natural products. Typically, 3,4- bis ( benzyloxy ) benzaldehyde (7) on Wittig reaction with triphenyl (11- phenylundecyl ) phosphonium bromide (20) and subsequent catalytic hydrogenation of the resultant olefin gave compound (5) in 59% overall yield.
The X-Ray Crystal Structure and Photochemistry of 22-α-Hydroxystictan-3-One; a Triterpenoid Keto Alcohol From Pseudocyphellaria Species
Authors: Wilkins AL , Goh EM
Published: September 2010

The crystal structure of 22α-hydroxystictan-3-one has been determined by X-ray diffraction. Rings A and B of this keto alcohol have been shown to adopt twist boat conformations. Despite the presence of the twist boat ring A system photochemical rearrangement of the keto alcohol proceeds to give 3,4-secostictane derivatives analogous to those afforded by other 3-oxo-4,4-dimethyl steroids and triterpenoids in which ring A adopts a flattened chair conformation.
Structural Studies of the Template Effect: Formation of Macrocyclic Ligands Incorporating Heavy Donor Atoms
Authors: Harrowfield JM , Patrick JM , Skelton BW , White AH
Published: September 2010

X-ray structural studies of both products and reactants involved in the template formation of the macrocycle 'cyclars' (5,14-dimethyl-5,6- 7,9,14,15,16,18-octahydrodibenzo[e,l]- dithiadiarsacyclotetradecin ) have been performed, and the results used to define several aspects of possible reaction mechanisms. The structure of the racemic form of cyclars shows that this free arsenic/sulfur donor ligand is not 'preorganised' for square-planar coordination, though metal ion/donor atom distances in its palladium(II) complex (Pd-As 2.388 Ǻ, Pd-S 2.314 Ǻ) do appear normal. In contrast, the structure of the palladium(II) complex of the arsenic meso ligand, which is not a direct product of the template reaction, shows relatively short palladium/donor atom distances (Pd-As 2.361 Ǻ, Pd-S 2.278 Ǻ), suggesting that template formation may be inhibited because the 'hole size' of this ligand diastereomer is too small for palladium(II). Further, the structure of a bis (bidentate) ligand precursor complex which could, in principle, generate the meso macrocycle shows that, in the solid at least, the reactant groups are not favourably juxtaposed for cyclization. The structure of the platinum(II) complex of a sulfenate derivative of the same bidentate ligand suggests that electrophili c attack at coordinated thiolate, the crucial step in the macrocycle formation, is completely unselective for an unconstrained electrophile.
Oxidative Coupling of Lignans. II. Non-Phenolic Coupling of Diarylbutane Lignans Related to Matairesinol Dimethyl Ether
Authors: Buckleton JS , Cambie RC , Clark GR , Craw PA , Rickard CEF , Rutledge PS , Woodgate PD
Published: September 2010

The non- phenolic oxidative coupling of some diarylbutane lignans related to matairesinol dimethyl ether (1) has been investigated. Coupling with a thallium(III) oxidant, prepared in situ from thallium(III) oxide and trifluoroacetic acid, converts these lignans efficiently into either dibenzocyclooctadiene or aryltetralin lignans. The dibenzocyclooctadiene lignan (5) prepared from oxidative coupling of matairesinol dimethyl ether has been converted into compound (26) which has significant in vitro antileukaemic activity. The structure of the isostegane (27) formed by oxidative coupling of dimethylbutane (14) has been confirmed by X-ray crystallography.
Ab initio Studies on Hydrazines: 1H-Pyrrol-1-amine (N-Aminopyrrole)
Authors: Riggs NV , Radom L
Published: September 2010

The geometries of four stationary structures of 1H-pyrrol-1-amine have been optimized with the 3-21G
and 3-21G(N*) basis sets. The lowest- energy and only equilibrium structure is the 'perpendicular' CS form (4) in which a pyramidal NH2 group is bisected by the plane of the pyrrole ring. The transition structure for inversion at the NH2 group is the perpendicular C2V form (2). After zero-point vibrational -energy corrections, it lies 24.5 kJ mol-1 [3-21G(N*)] above (4). The transition structure for rotation about the N-NH2 bond is the 'parallel' CS form (3) in which a plane of symmetry bisects both the pyrrole ring and the attached pyramidal NH2 group; it lies 26.5 kJ mol-1 above (4). The planar C2V structure (1) is a second-order saddle point lying 69.4 kJ mol-1 above (4). The spacing of NH-stretching frequencies calculated for the equilibrium structure (4) of 1H-pyrrol-1-amine is in the range for normal primary amines, unlike that for 1,1-dimethylhydrazine.
Preparation of a Deuterated Analog of Tetrahydropapaveroline Suitable for Use as an Internal Standard for G.C./M.S. Analysis of This Alkaloid: Retro Pictet-Spengler Condensation
Authors: Clezy PS , Duncan MW , Smythe GA
Published: September 2010

Attempts to prepare deuterated analogues of salsolinol and tetrahydropapaveroline by exchange procedures in D2O have demonstrated that the Pictet-Spengler reaction is a reversible process. Tetrahydropapaveroline can be readily obtained from papaverine by reduction with Zn/HCl followed by demethylation in a process which can conveniently be adapted to produce a (2H3)analogue.
A Valence-Bond Study of the Role of 3d Orbitals in the Bonding in ClF3
Authors: Maclaga n
Published: September 2010

Minimal basis set valence-bond calculations on ClF3, with, and without, the use of chlorine 3d orbitals are described. The most important structure is a spin-paired diradical structure. The covalent structure with three covalent Cl -F covalent bonds has a sufficiently low importance that 3d orbitals are not essential for describing the bonding in ClF3. Chlorine 3d orbitals do have a significant contribution to the calculated energy.
5-Coordinate Compounds of Nickel(II) and Copper(II) With the Triamine Diimine Ligands 13-imino-4,4,6,11,11-pentamethyl-3,7,10-Triazatetradec-6-en-1-amine and 4,6,11-Triethyl-13-imino-4,11-dimethyl-3,7,10-triazapentadec-6-en-1-amine
Authors: Curtis NF
Published: September 2010

Reaction of nickel(II) with 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene diperchlorate in the presence of ammonia yields a lilac- coloured complex of nickel(II) with 13-imino-4,4,6,11,11-pentamethyl-3,7,10-triazatetradec-6-en-1-amine, a pentadentate ligand with one primary and two secondary amino, plus one primary and one secondary imino , donor groups. The copper(II) complex of the ligand was formed from the nickel(II) compound by metal-ion substitution. The cations have d-d spectra indicative of five-coordination. The complex cations undergo a reversible protonation reaction with a change from five-coordinate to square planar, with a colour change for nickel(II) from lilac (triplet ground state) to yellow (singlet ground state), and for copper(II) from blue to violet. The compounds of the homologous ligand 4,6,11-triethyl-13-imino-4,11- dimethyl-3,7,10-triazapentadec-6-en-1-amine were similarly prepared, and have similar properties.