bluuebunny/crossref_metadata_2025 huggingface dataset:
A nuclear magnetic resonance study of molecular motion in (2,4,5-Trichlorophenoxy)acetic acid
Authors: Reddy KVG , Chary KVR , Sastry BA
Published: September 2010

Proton magnetic resonance
data in polycrystalline (2,4,5-trichlorophenoxy)acetic acid in the temperature
range 77-400 K are reported in this communication. After a correction is made
for the H-H distance in the methylene group the rigid lattice second moment (S2)
coincides with the experimental value in the temperature range 77-170 K. The
observed fall in S2 in the temperature range 170- 208 K is
interpreted as the result of the CH2COOH group reorientation. The
barrier height associated with the reorientation is found to be 8.728 kJ mol-
which indicates non-cleavage of hydrogen-bonding in the dimeric unit during
reorientation.
Nuclear magnetic resonance study of ligand exchange on Hexakis(1,1,3,3-tetramethylurea)lutetium(III)
Authors: Lincoln SF , Hounslow AM , Jones AJ
Published: September 2010

A 270-MHz lH n.m.r. study shows the rate of
1,1,3,3-tetramethylurea exchange on [Lu{OC(NMe2)2}6]2+
in CD3CN solution to be independent of [OC(NMe2)2]free
consistent with the operation of either a dissociative
mechanism or an interchange mechanism characterized by an encounter complex
stability constant ≥ 400. For this study
ligand exchange rate = 6kex[Lu{OC(NMe2)2}63+]
with kex(298.2
K) = 41.9 � 2.7 s-l, ΔH‡ = 41.7 � -0.6 kJmol-1 and ΔS‡ =
-74 � JK-1 mol-l. These data are compared with those for
the analogous scandium(III) and yttrium(III) systems and also those for some
eight-coordinate trivalent lanthanide systems. The preparations of [LuL6]
(ClO4)3, where L = OC(NMe2)2, OCMe(NMe2) and OCMe(Net2),
are reported.
Borates and phosphates of hexahydromuellitol and isomuellitol
Authors: Fazldeen H
Published: September 2010

Hexahydromuellitol
and isomuellitol are derivatives of a natural product (muellitol), and contain hydroxy
groups in their structures which should allow for the formation of 'cage'
compounds.
They
were each dissolved in a standard borate solution, and the pH values were
measured to determine if complexes of the tridentate type were formed.
Hexahydromuellitol caused the pH value of the solution to be depressed
considerably, but isomuellitol had no significant effect. Plots of the change in
pH value against time showed that a tridentate borate of hexahydromuellitol was
formed but not of isomuellitol.
Orthophosphates
were prepared from both compounds to verify the assigned conformations.
The
mono-and the di-orthophosphates of hexahydromuellitol were obtained, as was the
orthophosphate of isomuellitol.
Infrared vibration-rotation spectra of ethane. The parallel band, v9 + v10, of C2D6
Authors: Cole ARH , May KG
Published: September 2010

The weak combination band
of C2D6 near 2816 cm-1 has been studied at a
resolution of 0.012 cm-1. No
K-structure is observed indicating that (A'- B')-(A'- B') is very small (less
than c.10-4 cm-1).
The band has been measured from R(38) to P(36), and lines of two hot
bands, probably arising from excited levels of the torsion, and distinguishable
only after the resolution had been increased by deconvolution,
have also been measured and analysed. The constants determined from the mainband are: vo = 2816.2327 � 0.0012 cm-1, B' =
0.459675 � 0.000036 cm-1, B' = 0.458652 � 0.000061 cm-1, D'j = (4.18 � 0.36) × 10-7 cm-1
and D'j =(3.81 � 0.65 )10-7 cm-1.
N.M.R. studies of myelin basic protein. VII. Concentration and temperature dependence of amide resonances of the guinea pig encephalitogen in dimethyl sulfoxide
Authors: Sadikot H , Moore WJ
Published: September 2010

The encephalitogenic
peptide comprising residues 114-122 in human myelin basic protein, Phe-Ser-Trp-Gly-Ala-Glu-Gly-Gln-Arg, has been studied by
proton magnetic resonance at 400 MHz in dimethyl sulfoxide solutions.
Temperature coefficients of the chemical shifts of the amide resonances of Glu6,
Gly7 and Arg9 have low values indicative of shielding
from solvent. These data and nuclear Overhauser
enhancements between protons widely separated in the primary structure suggest
a compact structure for the peptide in dimethyl sulfoxide, probably associated
with a reverse turn about the Gly4Ala5 residues. In
freshly prepared solutions in the concentration range 0.20-5.0 mM, effects of intermolecular aggregation are not observed,
but such aggregation may occur under other conditions.
Some observations on the chemical and electrochemical reductions of 8-Bromobornan-2-one
Authors: Hamon DPG , Richards KR
Published: September 2010

Reduction of
8-bromobornan-2-one (1) by sodium-potassium alloy in ether, or hexane, gives p-menth-8-en-2-one (3) but in
hexamethylphosphoric triamide the product is bornan-2-one (2). Electrochemical
reductions at mercury cathodes both in dimethylformamide and hexamethyl-phosphoric triamide give mostly compound (3).
Reduction of bromide (1) by tributylstannane is
concentration dependent. In concentrated solution compound (2) is the major
product but in more dilute solutions compound (3) becomes predominant.
Copper complexes of Picloram: The crystal and molecular structures of Bis(4-amino-3,5,6-trichloropyridine-2-carboxylato)aquacopper(II) dihydrate and Bis(4-amino-3,5,6-trichloropyridine-2-carboxylato)bis(pyrimidin-2-amine)copper(II)
Authors: O'Reilly EJ , Smith G , Kennard CHL , White AH
Published: September 2010

The crystal structures of
two copper(II) complexes of the herbicide Picloram (4-amino-3,5,6-trichloro-
pyridine-2-carboxylic acid) have been determined by single-crystal X-ray
diffractometry. Bis(4-amino- 3,5,6-trichloropyridine-2-carboxylato)aquacopper(II)
dihydrate (1) is monoclinic, space group C2/c, with Z 4 in a cell of dimensions
a 15.593(6), b 7.940(6), c 16.983(6) �, β 107.58(3)�. The
structure was refined to a residual R 0.046 for 905 'observed' reflections.
Complex (1) is trigonal bipyramidal with the trigonal plane consisting of
oxygens from two picolinate ligands [Cu-O 1.995(5) �] and a water molecule [Cu-O
2.080(5) �]. The apical positions are occupied by pyridine ring nitrogens from
the Picloram ligands [Cu-N 2.021(5) �]. Bis(4-amino-3,5,6-trichloropyridine-
2-carboxylato)bis(pyrimidin-2-amine)copper(II) (2) is monoclinic, space group
P2,/c, with Z 4 in a cell of dimensions a
12.3 11(5), b 15.435(5), c 15.320(6) �, β 115.95(3)�, and
gave a final R 0.059 for 2429 'observed' reflections. In complex (2), the
copper(II) atom has a tetragonally distorted octahedral stereochemistry with
the Picloram ring nitrogens once again occupying the two axial positions [Cu-N
2.586(7) and 2.611(7) �]. The square plane consists of two carboxylato oxygens
[Cu-O 1.941(6) and 1.960(7) �] and two hetero-nitrogens from pyrimidin-2-amine
ligands [Cu-N 2.048(6) and 2.054(6) �].
An unexpected rearrangement of 1-Acetyl-3, t-5-dichloro-t-2,4-dimethyl- 2,5-dinitrocyclopent-3-en-r-1-ol; X-ray crystal structure of 3,t-5-Dichloro-t-6-hydroxy-2,4,6-trimethyl-r-2,5-dinitrocyclohex-3-enone
Authors: Hartshorn MP , Robinson WT , Sutton KH , Vaughan J , Wright GJ
Published: September 2010

1-Acetyl-3,t-5-dichloro-t-2,4-dimethyl-2,5-dinitrocyclopent-3-en-r-1-ol (11)
rearranges in acetone to give the C6-epimeric dinitrocyclohex-3-enone (13), the
structure of which was determined by X-ray crystal analysis. The base-catalysed
rearrangement of cyclohex-3-enone (13) is discussed.
The structure and function of oestrogens. IV. Synthesis of 17α-ethynyloestradiol specifically polydeuterated in ring C
Authors: Collins DJ , Sjovall J
Published: September 2010

Epoxidation of 17,17-ethylenedioxy-3-methoxyoestra-1,3,5(10),9(11)-tetraene( 5) by a two-phase
procedure gave the labile 9α,11α-epoxide (11), treatment of which with lithium perchlorate in benzene
gave 17,17-ethylenedioxy-3-methoxy-97#946;-oestra-1,3,5(10)-trien-11-one (7). Deuteration of this by
prolonged treatment with the monosodium salt of (O,O'-2H2)hydroquinone in dry (O-2H)methanol
gave mainly the 98,12,12-trideutero ketone (24) (92% 2H3). Reduction of this with lithium aluminium
deuteride to a mixture of the 11-epimeric alcohols (27a) followed by dehydration gave 17,17-ethylenedioxy-
3-methoxy(l1,12,12-2H3)oestra-1,3,5(10),9(11)-tetraene (26) which upon reduction with
lithium/ammonia gave 17,17-ethylenedioxy-3-methoxy(11ζ,12,12-2H3)oestra-1,3,5(10)-triene (25).
Hydrolysis and demethylation of (25) followed by treatment with potassium acetylide in liquid
ammonia yielded 3,17-dihydroxy-19-nor-17a-(11ζ, 12, 12-2H3)pregna-1 ,3,5(10)-trien-20-yne (29) (2H4,
9.2; 2H3, 84.1; 2H3, 3.1; 2H1, 2.2; 2H0, 1.3%).
Reduction of the trideutero 9(11)-ene (26) with hexadeuterodiborane followed by treatment
with alkaline hydrogen peroxide afforded 17,17-ethylenedioxy-3-methoxy(9α,11β,12,12-2H4)oestra-
1,3,5(10)-trien-11α-ol (30a). Reduction of the corresponding tosylate (30b) with lithium aluminium
deuteride, then hydrolysis, demethylation and ethynylation gave 3,17-dihydroxy-19-nor-17α-
(9,l 1,11,12,12-2H5)pregna-1,3,5(10)-trien-20-yne (35) (2H5, 84.5; 2H4, 8.5; 2H3, 4.4; 2H2,
0.9; 2H1, 0.8; 2H0, 0.9%).
Structure and stereochemistry in 'f-block' complexes of high coordination number. VI. Crystallographic characterizations of Bis[(1 ,1-dimethyl-3-oxobutyl)triphenyl-phosphonium] hexabromouranate(IV) and Tetrabromobis[ethane-1,2-diylbis(diphenylarsine) oxide]uranium(IV)
Authors: Kepert DL , Patrick JM , White AH
Published: September 2010

Complexes obtained by the
reaction of uranium pentabromide with
triphenylphosphine and with ethane-1,2-diylbis(diphenylarsine) (Ph2AsCH2CH2AsPh2)
have been characterized by single-crystal X-ray diffraction structure
determination at 295 K and shown to be [Ph3PCMe2CH2C(O)Me]2-
[Ubr6](1) and [Ubr4(Ph2As(O)CH2CH2AsPh2)2]
(2). Crystals of (1) are orthorhombic, Pbca, a 20.46(1), b 16.033(8), c 15.663(10) �, Z 4, the structure being refined to a residual of
0.07 for 990 independent reflections; in the centrosymmetric anion, U-Br
distances range from 2.750(5) to 2.803(5) �. Crystals of (2) are monoclinic, P21/c,
a 12.64(1), b 10.870(6), c 20.81(2) �,
110.88(2)�, Z 2, the structure being refined to a residual of 0.05 for 1531
independent reflections. In the centrosymmetric molecule, U-Br distances are
2.806(4) and 2.811(4) �; the diarsine oxide ligand
is unidentate, coordinated through the oxygen rather
than the arsenic with U-O 2.19(1) �.
Adsorption properties and stability of dihexadecyl phosphate vesicles
Authors: Tricot Y , Furlong DN , Sasse WHF , Daivis P , Snook I
Published: September 2010

The adsorption of the
photochemical sensitizer tris(2,2'-bipyridine)ruthenium(II) on dihexadecylphosphate vesicles has been determined as a
function of the pH and ionic strength of the dispersing medium. The adsorption
density is a maximum at pH 7.5 � 0.5 and with minimum ionic strength(pH
adjusted by adding NaOH). The stability of the
vesicles with respect to flocculation, in the presence of adsorbed sensitizer,
is increased when the pH is raised from 3.3 to 7.5. The presence of an amine
buffer at 5 x 10-2 at pH 7.8 reduces the adsorption density by more
than 90%. The relevance of these results to the interpretation of
photochemistry experiments (in conjunction with photochemical hydrogen
production from water) is discussed.
Paramagnetic organometallic molecules. XV. Electron attachment reactions of metal carbonyls
Authors: Huffadine AS , Peake BM , Robinson BH , Simpson J
Published: September 2010

A number of polynuclear metal carbonyl complexes can be used as
substrates for electron attachment reactions induced by the photoionization
of N,N,N',N'-tetramethyl-p-phenylenediamine.
Theproducts of such reactions
are derived from metal carbonyl radicals produced by cleavage of the metal-metal
bonds.
Bromination of azobenzenes by acidified hypobromous acid; Orientation, reactivity and mechanism
Authors: Christoforou D , Happer DAR , Munro MHG
Published: September 2010

The rate of bromination of
azobenzene by acidified hypobromous acid has been measured and compared with
those of benzene, toluene, and bromobenzene under the same conditions.
Determination of o/m/p ratios for attack on azobenzene show that the rate of attack
at the meta position is much lower than expected on the basis of the Hammett
σm value for the phenylazo substituent. Abnormally low amounts of meta isomer
were also observed for the case of bromobenzene, but not toluene. The rates of
bromination of two monosubstituted azobenzenes (m-Br, and p-F) were also deter-
mined and compared with that of azobenzene.
The radiation chemistry of aqueous ferrous sulfate solutions at natural pH
Authors: Matthews RW
Published: September 2010

The yield of FeIII species has been determined in FeSO4 solutions irradiated at natural pH with 60Co
γ-rays for a wide range of solute conditions. The stoichiometry of the hydrogen peroxide reaction was
investigated and found to be abnormal if H2O2 is present in excess. If, however, FeS04 is present
in excess, as it is in the irradiation of FeSO4 solutions, deviations from the normal stoichiometry
are trivial. In nitrous oxide saturated solutions initial G(FeIII) values were found to be from 6.90
to 7.72 for FeSO4 concentrations in the range (0.5-2.0) × 10-3 M. Non-linearity in the yield of ferric
ion concentration against dose plots was attributed to competition between hydrogen atom reduction
of ferric species with hydrogen atom oxidation of ferrous species. The reaction between hydrogen
atom and the ferric species was estimated to be close to diffusion controlled. In aerated solutions,
the FeIII yield was, within experimental error, a linear function of dose for FeSO4 concentrations in
the range (0.5 - 2.0) × 10.-3 M with G(FeIII) values of 12.27 ± 0.06, 12.62 ± 0.07 and 12.77 ± 0.10 for
0.5, 1.0 and 2.0 × M respectively. At lower FeSO4 concentrations. deviation from linearity
was noticeable. The deviation was attributed to competition between FeII and FeIII species for the
O2- radical anion. k(O2-· + FeII)/k(O2-·+ FeIII) was determined to be about 4.0. In deaerated solu-
tion, the FeIII yield against absorbed dose for 1 × M FeSO4 solution was followed to extended
doses. A limiting FeIII yield of about 0.75 times the aerated solution yield was observed in the closed
system. The data were quite well described by values calculated from the reaction mechanism,
published rate constants and the rate ratio of 0.016 for k(H· + FeII)/k(H· + FeIII) determined from
the N2O experiments, and demonstrate the importance of reducing radical reactions with insoluble
ferric species.
Thermal dissociation of thiuram disulfides in solution; an electron spin resonance and kinetic study
Authors: Nichols PJ , Grant MW
Published: September 2010

Tetraisopropylthiuram disulfide dissociates reversibly in solution to form
dithiocarbamate thioradicals
which can be detected by e.s.r. (g 2.015). The thermodynamics of the dissociation has been examined
in decalin by quantitative e.s.r.
and a dissociation enthalpy of 104 � 2 kJ mol-1 and anentropy of dissociation of 57 � 5 JK-1 mol-1
has been obtained. Replacing the isopropyl group by other alkyl groups
significantly affects the extent of dissociation which decreases in the
sequence isopropyl ≈ cyclohexyl > ethyl ≈ methyl > benzyl as
the alkyl group is changed. Studies of the kinetics of dissociation of the thiuram disulfides are consistent with the e.s.r, observations and indicate that thio
radical recombination occurs at a near diffusion-controlled rate.
The synthesis and chemistry of 2-Methylpyrimidine-4,6-dithiol and some related compounds
Authors: Hurst DT
Published: September 2010

2-Methylpyrimidine-4,6-dithiol
has been synthesized and has been converted into 2-methyl-6-
methylthiopyrimidine-4-thiol, 4,6-bismethylthiopyrimidine and
6,6'-dithiobis(2-methylpyrimidine-4- thiol).
Oxidation of 4,6-bismethylthio-2-methylpyrimidine with 1, 2, 3 and 4 equiv. of m-chloroper-
benzoic acid has been shown to result in the formation of the easily isolable methylsulfinyl(methylthio)-, bis(dimethylsulfinyl)-, methylsulfinyl(methylsulfonyl)- and bismethylsulfonyl-pyrimidine,
respectively. Some further reactions of the above compounds are described and
the synthesis of some other pyrimidines having sulfur-containing substituents
is also described.
Base-catalysed linkage isomerization of pentaamminechromium(III) complexes of urea and formamide
Authors: Curtis NJ , Lawrance GA , Sargeson AM
Published: September 2010

The complexes Cr(NH3)5L3+
[L = OCHNH2, OC(NH2)2 and OC(NHMe)2]
have been synthesized as the O-bound
isomers. At 25�C in aqueous base (pH c. 10-14) they isomerize
to the deprotonated N-bound isomers without competitive hydrolysis. Reacidification
regenerates the O-bound isomer
rapidly and completely. The second-order rate constants and pKa
values of the amide complexes (I 1.0
M, 25�C) are respectively: 37.0 � 1.5 dm3 mol-1 s-1
and 11.72 � 0.06 for formamide; 0.324 � 0.004 dm3
mol-1 s-1 and l3.50 � 0.05 for urea; 0.0375 � 0.0020 dm3
mol-1 s-1 and 14.0 � 0.2 for N,N'-dimethylurea. The observations for
chromium(III) parallel similar behaviour in cobalt(III) and rhodium(III)
analogues, but are unusual for chromium(III) chemistry.
Model calculations of isotope effects. VII. Deprotonation of 2-nitropropane by oxy anion bases
Authors: McLennan DJ
Published: September 2010

Model calculations of
primary and secondary deuterium isotope effects for the hydroxide-induced
deprotonation of 2-nitropropane are reported. Various transition-state models
have been examined in an effort to reproduce experimental results. A purely
pyramidal transition state in which proton transfer has run far ahead of carbon
rehybridization and charge delocalization is a
successful model as far as isotope effects are concerned, but may fail on other
counts. Three incipient trigonal models for the transition state have been
tested, and, although none can be firmly eliminated by the resultant isotope
effects, those involving the proton transfer's running ahead of electron
delocalization and perhaps carbon rehybridization are favoured.
Model calculations of isotope effects. VIII. Deprotonation of nitroethane
Authors: McLennan DJ
Published: September 2010

Transition-state models for
the base-promoted deprotonation of nitroethane have
been designed, and primary and secondary hydrogen-deuterium kinetic isotope
effects have been calculated. Comparison of the results with experimental
values of the primary isotope effects allows no firm conclusions to be reached
concerning probable transition-state structures. However, the secondary α-deuterium
isotope effect comparison disqualifies from consideration those transition
states in which rehybridization of Cα and delocalization of the partial negative
charge by the nitro group keep pace with the extent of deprotonation.
Transition-state models wherein Cα is carbanionic
and essentially pyramidal yield theoretical isotope effects lying within the
experimental range.
Model calculations of isotope effects. IX. Origin of large hydrogen and carbon isotope effects in the deprotonation of 2-nitropropane by pyridine bases
Authors: McLennan DJ
Published: September 2010

The abnormally large
primary hydrogen and carbon kinetic isotope effects found in the deprotonation
of 2-nitropropane by hindered pyridine bases are investigated by means of model
calculations. Transition-state models have been varied between tight and loose
extremes, and between carbanion-like and nitronate-like structures. The only
models that reproduce the experimental findings are those in which the sum of
the bond orders to the transferring proton is less than unity (loose transition
states) and which are subject to tunnelling
corrections.
The nitration of 2,4-dibromo-3,5,6-trimethylphenol and some reactions of polysubstituted phenols with nitrogen dioxide; X-ray crystal structure of 4-Acetyl-1-bromo-r-3,c-4-epoxy-2,t-5-dimethyl-3,5-dinitrocyclopentene
Authors: Hartshorn MP , Martyn RJ , Robinson WT , Sutton KH , Vaughan J , White JM
Published: September 2010

Nitrations of phenols (3a), (3b), (7) and (8) with nitrogen
dioxide in cyclohexane give similar patterns of reaction to those with fuming
nitric acid in acetic acid. Nitration of 2,4-dibromo-3,5,6-trimethyl- phenol
(19) with nitrogen dioxide gives isomeric trinitrocyclohex-3-enones (24), while
fuming nitric acid reactions yield either the trinitro
ketone (24a) and the cis-dinitro ketone (25) or the C2-epimeric ketones (25) and
(26) depending upon the reaction conditions. Some reactions of these products
are described, and the X-ray crystal structure of the epoxycyclopentene
derivative (30) is reported.
The synthesis of the N-methyl analogue of S-adenosylmethionine; N.M.R. observation of diastereomers
Authors: Davis M , Dudman NPB , White HF
Published: September 2010

The N-methyl analogue (1; X
= N-Me) of S-adenosylmethionine has been synthesized;
the intermediates and the end-product are racemic at the amino acid α-carbon,
and show diastereomeric splitting in their 13C
n.m.r. spectra.
Solvation of ions. Some applications. V. Electrolytic recovery of silver from non-aqueous solutions
Authors: Jayasekera S , Avraamides J , Parker AJ
Published: September 2010

Electrolysis of a dimethyl
sulfoxide solution containing AgCl2- and CuCl2- has been
shown to produce high-purity, adherent, non-dendritic
cathode silver with a current efficiency of over 80%. At the anode, CuCl2-
was oxidized to Cu2+. An optimum electrolyte/solvent system was
chosen after a study of the various parameters contributing to the conductivity
of the solution. Diffusion coefficients and Tafel
slopes were measured, as were the various potentials contributing to the cell
voltage. Good silver deposits were obtained by using 0.75 M CaCl2.2H2O,
0.5 M AgCl and 0.5 M CuCl
in dimethyl sulfoxide at 50�C at a cathode current density of 5 mA cm-2. A practical electrolysis cell is
proposed for use with a cyclic leach-electrowin process for recovering pure silver
from various high-grade secondary residues.
A quasi-lattice quasi-chemical theory of preferential solvation of ions in mixed solvents
Authors: Marcus Y
Published: September 2010

The quasi-lattice
quasi-chemical theory is used with a single fitting parameter (Z, the number of
nearest neighbours) and data independent of the
transfer to solvent mixtures, to describe quantitatively the standard molar
Gibbs free energy of transfer of ions from a reference solvent to solvent
mixtures, ΔGt� (X, W → S1
+ S2), as a function of the composition (mole fraction, x). The
independent data include the ΔGt� to
the two pure solvents and the excess Gibbs free energy of mixing of these
solvents. A defined preferential solvation parameter,
g(x), is a convenient measure that is
obtained from this treatment. The advantages of employing volume fractions, �,
and g(�) rather than mole fractions, x, and g(x), are examined. The theory is
applied to the transfer from water of Cl- to ethanol, of Ag+ to acetonitrile or dimethyl sulfoxide, and of NaCl to methanol, and of Na+ from acetonitrile
to dimethyl sulfoxide as illustrative examples, comparing the calculated values
to experimental data.
Thermodynamic properties of peptide solutions. The relative partial molar enthalpies of aqueous solutions of glycylglycylglycine, glycylglycylalanine and alanylglycylglycine
Authors: Kumaran MK , Watson ID , Hedwig GR
Published: September 2010

The enthalpies of dilution
at 298 K of aqueous solutions of the tripeptides glycylglycylglycine,
glycylglycylalanine and alanylglycylglycine have been determined by flow
microcalorimetry. From these data the partial molar enthalpies of the solvent
in the solutions have been calculated. The results indicate that water
side-chain interactions make an important contribution to the solvation of
peptides.
A structural and carbon-nitrogen bond rotation study of N,N,N',N',2,2-hexamethylpropanediamide
Authors: Lincoln SF , Hounslow AM , Maeji NJ , Hambley TW , Snow MR , Jones AJ
Published: September 2010

The molecular structure of
N,N,N',N',2,2-hexamethylpropanediamide has been determined in the solid state
by X-ray diffraction methods. The structure of Me2NCOCMe2CONMe2
may be broadly described as two planar Me2NCO entities intersecting
at the tetrahedral -CMe2- site. The angle between the normals to the two Me2NCO planes is 104.6�, and
the two oxygen atoms are disposed outwards from the molecule and away from each
other. Proton (270-MHz) n.m.r. studies yield k(320 K) 32.0 � 3.2 s-1,
ΔH‡ 69.5 � 0.4 kJ mol-1 and ΔS‡ 0.6 � 1.1 J K-1
mol-1 for rotation of the N-methyl groups about the carbon-nitrogen
bonds in CD3NO2 solution. Similar magnitudes for the
kinetic parameters characterizing this process are obtained in CDCl3,
and CD3CN solutions.
Photoreduction of deazaflavin. Spectroscopic investigations
Authors: Bliese M , Launikonis A , Loder JW , Mau AWH , Sasse WHF
Published: September 2010

Photophysical and photochemical properties of deazaflavin
(3,10-dimethylpyrimido[4,5-b]quinoline- 2,4-(3H,10H)-dione) and some of its
1,5-dihydro derivatives have been investigated. Contrary to earlier reports the
photodimer of deazaflavin
is non-luminescent throughout the temperature range 77-295 K. Excitation of deazaflavin in the presence of oxalate anion (acetate
buffer pH 5.0) causes photodimerization with quantum efficiencies exceeding
unity. A mechanism involving a triplet excimer of deazaflavin has been proposed
for this reaction.
The phase behaviour of binary mixtures containing hydrogen
Authors: Burgess AK , Young CL
Published: September 2010

The solubility and gas-liquid critical temperatures of mixtures of hydrogen with the permanent
gases has been discussed in terms of the one-fluid model and 'hard sphere + attractive term' equations
of state as proposed by Carnahan and Starling and Guggenheim. The solubilities of hydrogen and
'moderately-sized' hydrocarbons such as benzene and cyclohexane and higher hydrocarbons such
as decalin and bicyclohexyl have also been discussed in terms of the one-fluid model. Finally,
examples of the solubilities of other small molecules, methane, nitrogen and carbon dioxide, in both
'moderately sized' and higher hydrocarbons are considered in terms of the one-fluid model.
It is concluded that :
(A) The best fit values of the interaction parameter, ζ, for all mixtures, except the permanent
gas+ hydrogen systems, are considerably smaller than predicted by the Hudson and McCoubrey
rule.
(B) The values of ζ for the hydrogen+ hydrocarbon mixtures are considerably smaller than those
for similar hydrocarbons + other small molecules.
(c) Often the best fit value of ζ decreases with an increase in temperature.
Some common problems concerning solvent polarization and dielectric behaviour at ions and electrode interfaces
Authors: Conway BE , Marshall S
Published: September 2010

The sensitivity of the
dependence of ionic hydration properties of simple cations and anions on ionic
radius is compared and related to the dielectric polarization in the solvent,
near the ion. Corresponding dielectric polarization of the water solvent in the
interphase at the surface of charged electrodes is
evaluated on the basis of several models of oriented water dipoles at
electrodes and compared with the situation at ions. It is pointed out that
previous theories of the double-layer at electrodes have considered either the
solvent polarization in the absence of adsorbed ions or the behaviour of ions
independently of the solvent polarization by the electrode surface charge.
Calculations are given that indicate that the surface concentrations of adsorbed
ions at electrodes are commonly sufficient to cause a major influence on the
behaviour of interphasial water in addition to that
arising from the effect of electrode surface charge. Further, repulsion, due to
overlap of Gurney cospheres of ions, will be an
important factor in ionic interactions laterally within the double-layer.
Colloidal platinum sols: anion effects on coagulation behaviour
Authors: Furlong DN , Sasse WHF
Published: September 2010

The concentration of added
electrolyte required to induce coagulation of a platinum sol has been
determined for a range of electrolytes. It has been found that, for
electrolytes in which the anion contains lone-electron-pair substituents, sol
stability is significantly enhanced compared with that observed when similar
but non-electron-pair-containing anions are used. It is proposed that the lone
electron pairs enable anion adsorption on negative platinum surfaces despite
the Coulombic repulsions present.
The chemical and electrochemical reductions of 5-bromodecalone [(4aα,5α,8aβ)-5-Bromooctahydronaphthalen-1(2H)-one] and 4-bromodecalone [(4α,4aβ,8aα)-4-bromooctahydronaphthalen- 1(2H)-one]
Authors: Hamon DPG , Richards KR
Published: September 2010

5-Bromodecalone (1) was
prepared by the reaction of potassium bromide in acetonitrile
on(4aα,5α,8aβ)-5-tosyloxyoctahydronaphthalen-l(2H)-one (15) with
apparent retention of configuration. It was also prepared by hydrogen bromide
cleavage of (3aRS,3bRS,7aSR)-octahydro-7H-cyclopenta[1,3]cyclopropa[1,2]benzen-7-one
(17). On reaction with sodium potassium alloy ketone (1)gives α-decalone (33) and ketone (17) as the principal products
whereas reduction with tributylstannane gives only
ketone (33). Electrochemical reduction of ketone (1) gives trans-cyclodec-5-en-1-one (3) as well as ketones (17) and (33).
4-Bromodecalone (2) was prepared from(4a,4aα,8aβ)-4-tosyloxyoctahydronaphthalen-1(2H)-one
(29), by the reaction with potassium bromidein acetonitrile, with inversion of configuration.
Electrochemical reduction of ketone (2) gives trans-1-acetyl-2-vinylcyclohexane (36), α-decalone
(33), (E)-cyclodec-4-en-1-one (4) and (laRS,-1bSR,5aRS,6aRS)-octahydrocycloprop[a]inden-6(6aH)-one(24).
Regioselectivity in ring-expansion of 1-substituted Bicyclo[2.1.l]hexan-2-ones: preferential migration of methylene over bridgehead carbon
Authors: Della EW , Pigou PE
Published: September 2010

Ring expansion of several
1-substituted bicyclo[2.1.1]hexan-2-ones has been investigated in order to
compare the effect of substitution on the migratory aptitude of the bridgehead
carbon in relation to the methylene carbon. In the cases examined it was observed
that there is a marked preference for migration of the methylene carbon, with
the substituted substrates displaying higher regioselectivity
than the parent ketone. In the rearrangement of both 1-fluoro- and
1-chloro-bicyclo[2.1.1]- hexan-2-one, migration of the methylene carbon occurs
exclusively.
Studies of Australian soft corals. XXXIII. New cembranoid diterpenes from a Lobophytum species
Authors: Bowden BF , Coll JC , Tapiolas DM
Published: September 2010

The isolation of two new cembranoid diterpenes, (14S,1E,3E,7E)-14-acetoxy-11,12-epoxycembra-1,3,7-triene
and the corresponding 14-alcohol, is reported from the soft coral Lobophytum sp. A minor
component in the extract (3S,4S,1lS,12S,1E,7E)-3,4:11,12-bisepoxycembra-1,7-diene
was identified but may be artefactual as it is the
sole product of the aerial oxidation of the major metabolite(11S,12S,1
E,3E,7E)-11,12-epoxycembra-1,3,7-triene.
Further examples of stereospecific epoxidationsare
reported.
Metal template reactions. XVIII. Macrocyclic metal complexes derived from 2,6-diacetylpyridine and some primary diamines with additional nitrogen donor atoms
Authors: Black DSC , Rothnie NE
Published: September 2010

Macrocyclic nickel(II), copper(II) and cobalt(II) complexes (6),
(8), (10), (12) and (14) have been prepared from 2,6-diacetylpyridine, the
appropriate metal salt and the primary diamines
2,2'-(iminodimethylene)bisaniline (5),
azobenzene-2,2'-diamine (7), 2,2'-iminobisaniline (9), 2-amino-
N-(2'-aminopheny1)benzamide (11) and 2-amino-N-(2'-aminobenzoy1)benzamide (13)
respectively. The primary diamines
2,2'-diaminooxanilide (15) and N,N'-(2'-phenylene)bis(2'-aminobenzamide) (16)
could not be incorporated into macrocyclic ligands by
similar techniques.
Synthesis of m-aminomethylbenzoic acid peptides
Authors: Stewart FHC
Published: September 2010

Several peptides
incorporating m-aininomethylbenzoic
acid have been synthesized. This amino acid is a conformationally
rigid model of a trans dipeptide unit. The products include an analogue of leucine-enkephalin.
Synthesis of 2,3-Dihydro-1,4,5-benzodioxazocines. X-ray structure of 6-Phenyl-2,3-dihydro-1,4,5-benzodioxazocine
Authors: Browne EJ , Engelhardt LM , White AH
Published: September 2010

Derivatives (6a-c) of the
1,4,5-benzodioxazocine ring system have been prepared in low-to-moderate yields
by hydrazinolysis of
{2-[2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)oxyethyloxy]aryl}phenylmethanones(5a-c),
and cyclization of the products at pH c. 4. Only in the case of (6b) was a
trace of a cyclic dimer (7b) detected, in contrast to the analogous
preparations of the 2H-1,5,6-benzodioxazonine
derivatives (1a-c) where 18-membered cyclic dimers (8a-c) formed as
by-products. The crystal and molecular structure of
6-phenyl-2,3-dihydro-1,4-5-benzodioxazocine (6a) has been determined by
single-crystal X-ray methods.
A synthesis of 6- and 4-hydroxymethyl derivatives of pyridin-3-ols
Authors: Deady LW , Payne M
Published: September 2010

Studies are reported of dimethylaminomethylation of pyridin-3-ols-in which a bromo
substituent is used as a temporary block to control orientation-and subsequent
conversion into hydroxymethyl analogues.
The dissolution of copper metal by acidified iron(III) in acetonitrile-water solutions
Authors: Couche RA , Ritchie IM
Published: September 2010

The kinetics and
electrochemistry of the dissolution of a rotating copper disc in various
acidified acetonitrile-water mixtures containing
iron(III) as the oxidant are described. The reaction kinetics were investigated
by a chronopotentiometric method in which the time
taken for a copper film of known thickness to dissolve was determined. The
reaction was shown to be diffusion-controlled over the temperature range
(270-304 K) and composition range (1.0-14.5 mol dm-3 acetonitrile) investigated, good agreement being obtained
between rate constants calculated from kinetic measurements and those
calculated from electrochemical (cathodic polarization) measurements. From
these and kinematic viscosity data, diffusion coefficients for iron(III) in
acetonitrile-water mixtures were calculated. It was found that, associated with
a discontinuous change in the kinematic viscosity at
290 K, there was a corresponding change in the diffusion coefficient. The
activation energy for the high-temperature diffusion process was lower than
that for the low-temperature process. It was also found that the diffusion
coefficient decreased with increasing acetonitrile
concentration. Corrosion potential measurements as a function of disc rotation
speed and iron(III) concentration are reported. From these measurements, it was
inferred that the anodic reaction is under mixed control.
Structural studies on catalysts and catalyst precursors. The X-ray structure determination of (3-Allylpentane-2,4 dithionato)chloro(triethylphosphine)nickel(II), Ni(asacsac)(Pet3)Cl
Authors: Cavell KJ , Hay DG , Masters AF , Williams GA
Published: September 2010

The preparation and
characterization of Ni(asacsac)(PEt3)Cl by
single-crystal X-ray diffraction [refined to R = 0,049, R' = 0,052 with 1888
data having I ≥ 3σ(I)],
are reported. The compound crystallizes as discrete molecules in the monoclinic
space group P21/c, with a
= 10,078(2), b = 8.202(3), c = 22.984(5) �, β = 97.57(2)�, U
= 1883.3 �3 and Z = 4. The nickel-donor atom bond distances are Ni-S
(trans Cl) 2.083(2), Ni-S (trans P) 2.127(2), Ni-Cl 2.208(2) and Ni-P 2,234(2) �,
with the ligands at angles S-Ni-S 96.8(1), S-Ni-C1 86.2(1), S-Ni-P 90.7(1) and
Cl-Ni-P 86.9(1)�. The coordination about the nickel(11) centre is approximately
planar, but the planes NiSS and NiPCl
are inclined at 8.3�. Comparisons are made with the structures of related
compounds, in particular, that of Ni(sacsac)PEt3Cl.
Metal complexes of 1,10-phenanthroline derivatives. XIV. Complexes of 1,10-Phenanthrolin-2-yl(pyridin-2-yl)amine
Authors: Abushamleh AS , Goodwin HA , Benson CG , Long GJ
Published: September 2010

1,10-Phenanthrolin-2-yl(pyridin-2-yl)amine
has been prepared in low yield from 2-chloro-1,10- phenanthroline
and pyridin-2-amine. The molecule coordinates as a tridentate chelating agent
of the ter-imine type and produces low-spin complexes
with iron(II) in both its neutral and anionic forms. The bis(ligand) cobalt(II)
complex is high-spin. Although the ligand provides a slightly weaker field than
terpyridine, electronic and Mossbauer
spectral data indicate a less distorted metal ion environment in its complexes,
compared with those of terpyridine. This is
correlated with the presence of the six-membered chelate ring.
N.M.R. studies of aldonolactones. The 80-MHz proton N.M.R. and 20-MHz proton-coupled 13C N.M.R. of D-Arabinono-1,4-lactone in D2O solutions
Authors: Wong H
Published: September 2010

The 80-MHz proton n.m.r.
spectrum of D-arabinono-1,4-lactone in D2O has been simulated and
the results utilized in the assignment of the 20-MHz proton-coupled 13C
n.m.r. spectrum. Two-and three-bond carbon-proton coupling constants have been
derived from computer simulations and are discussed in terms of the dihedral
angles in the preferred conformation.
Pterins. IX. The conformations of (6R)- and (6S)-2-Amino-6-[(1'R,2'S)-1',2'- dihydroxypropyl]-5,6,7,8-tetrahydropteridin-4(3H)-one [L-erythro-5,6,7,8-Tetrahydrobiopterin] hydrochlorides and their tetraacetyl derivatives
Authors: Armarego WLF , Randles D , Taguchi H , Whittaker MJ
Published: September 2010

Catalytic reduction of biopterin (1) in trifluoroacetic acid gives, after
acetylation, a 1 : 3 mixture of (6S)- and (6R)- (4)
tetraacetyl-5,6,7,8-tetrahydrobiopterin. Catalytic reduction of triacetylbiopterin (2) in ethanol yields, after
acetylation, a 3 : 1 mixture of (6S)- and (6R)- (4) tetraacetyl-
5,6,7,8-tetrahydrobiopterins. These were separated and gave on hydrolysis (6S)-
and (6R)-(3) 5,6,7,8- tetrahydrobiopterin
hydrochloride. The diastereomeric acetyl derivatives
and hydrochlorides have distinct 1H n.m.r. spectra which can be used
to identify them, and provide information about the conformations of the
tetrahydropyrazine rings and the 6-dihydroxypropyl side chains.
Synthesis of 4H-Thieno[2,3-d]azonine and Thieno[2,3-d]azecine derivatives
Authors: Browne EJ
Published: September 2010

Derivatives of two new
thieno medium-ring heterocyclic systems have been prepared by ring degradation
using cyanogen bromide-induced solvolysis of tricyclic bases. Reaction of a
hexahydrothieno[2,3-glindolizine (4a) and a hexahydro-7H-thieno[3,2-a]quinolizine (4b) with cyanogen bromide and magnesium
oxide under solvolytic conditions yielded derivatives of hexahydro-4H-thieno[2,3-d]azonine (5a) (6a) and
octahydrothieno[2,3-d]azecine (5b) (6b), respectively. Functional group
interconversions of these medium-ring systems are described, including
oxidations to cyclic ketones. The 9a-phenyl derivative of (4a) reacted
similarly. By contrast 10b-phenyl derivatives (10a,b) of a
hexahydropyrrolo[2,1-a]isoquinoline reacted under these conditions to give
medium-ring elimination products, derivatives of tetrahydro-1H-3-benzazonines.
The structure determination of a new cembranolide diterpene from the soft coral Lobophytum cristigalli (Coelenterata, Octocorallia, Alcyonacea)
Authors: Bowden BF , Coll JC , de Costa MSL , Mackay MF , Mahendran M , de Silva ED , Willis RH
Published: September 2010

A specimen of Lobophytum cristigalli
collected in Sri Lanka afforded two cembranolide
diterpenes
(7E,11E,1R,2S,3R,4R,14S)-14-acetoxy-3,4-epoxycembra-7,11,15-trien-17,2-olide
(6)* and the corresponding alcohol (7). Their structures were deduced
spectroscopically and detailed stereochemistry of (6)
was determined by X-ray crystallography.
Nitrones and oxaziridines. XXXIII. Synthesis of bridgehead-hydroxylated bicyclic 1-pyrroline 1-oxides
Authors: Black DSC , Johnstone LM
Published: September 2010

The α-hydroxy-γ-nitro
ketones (3), (9, (7) and (10) have been prepared from the respective γ-nitro
ketones (1), (4), (6) and (9) by a sequence involving formation and epoxidation of the intermediate enol
acetate, and hydrolysis of the epoxide. Reductive cyclization
of the α-hydroxy-γ-nitro ketones (3), (7) and (10) gave the
bridgehead-hydroxylated nitrones (ll), (12) and (13) respectively.
Structural studies of technetium complexes. V. The preparation and crystal structure of Dichlorobis(diethyldithiocarbamato)thionitrosyltechnetium(III)
Authors: Baldas J , Bonnyman J , Mackay MF , Williams GA
Published: September 2010

Dichlorobis(diethyldithiocarbamato)thionitrosyltechnetium(III),
[Tc(S2CNEt2)2Cl2(NS)], has been
prepared by the reaction of [Tc(S2CNEt2)2N]
with either disulfur dichloride or thionyl chloride. The crystal structure of
[TC(S2CNEt2)2Cl2(NS)] has been
determined by single-crystal X-ray diffraction methods at 15�C. Crystals are
orthorhombic, space group Pcmn, with a 8.936(1), b 15.681(1), c 28.445(7) �, and Z 8. Automatic
diffractometry has provided significant Bragg intensities for 2078 independent
reflections, and the structure has been refined by full-matrix least-squares
methods to R 0.078. The crystal lattice is disordered across a
non-crystallographic mirror plane, the degree of disorder being 4.0(2)% for the
crystal described above, and 21.9(7)% for another crystal initially used to
obtain an intensity data set. There are two independent molecules of [Tc(S2CNEt2)2Cl2(NS)]
in the asymmetric unit, and in each the technetium atom is seven-coordinate
with a pentagonal-bipyramidal coordination environment. The Tc=N=S bonding is
linear with Tc=N c. 1.75 and N=S c. 1.52 �, which indicates that the
thionitrosyl group is a three-electron donor with a formal positive charge.
This is only the third crystal structure of a complex containing the thionitrosyl
group to be determined, and the first for technetium.
The reaction of 4-t-Butyl-2,6-dimethylphenol with nitrogen dioxide ; the formation of four 2,5,6-Trinitrocyclohex-3-enones and 4-t-Butyl-c-6-hydroxy-2,6-dimethyl-r-2,c-5-dinitrocyclohex-3-enone
Authors: Hartshorn MP , Penfold BR , Sutton KH , Vaughan J
Published: September 2010

Reaction of
4-t-butyl-2,6-dimethylphenol (13) with nitrogen dioxide in cyclohexane proceeds
with some nitro-de-t-butylation, but reaction in benzene yields the four
possible 2,5,6-trinitrocyclohex- 3-enones (18), (19), (20), (21) and the
hydroxy dinitro ketone (22). The structures and stereochemistry of these
products were determined by single-crystal X-ray analysis. The mechanistic
significance of the formation of these trinitro ketones (18)-(21) is discussed.
The protonation reactions of catechin, epicatechin and related compounds
Authors: Kennedy JA , Munro MHG , Powell HKJ , Porter LJ , Foo LY
Published: September 2010

The protonation reactions
for catechin and epicatechin
have been studied at 25�C, I 0.10M (KCl). Equilibrium
constants Kn for the protonation steps of
the anions L4- have been determined from potentiometric
and/or spectrophotometric measurements. The logKn values for the epimers
differed significantly only for logKl and
logK4 (values for catechin 13.26 � 0.05,
11.26 � 0.06, 9.41 � 0.02, 8.64 � 0.01, and epicatechin
13.40 � 0.05, ll.23 � 0.06, 9.49 � 0.02, 8.72 � .01, n = 1-4 respectively).
These differences are ascribed to specific solvation
effects or ion associations between K+ and the ligand anions.
Epimerization was studied by h.p.l.c., and was found
to be minimal over the experimental time scale at pH c. 13.5. The ring on which each
stepwise protonation occurs was elucidated by reference to log Kn values measured for the model compounds catechol, 4-methylbenzene-1,2-diol, protocatechuic
acid and 3',4'-di-O-methylcatechin. The protonation sequence is B ring, A ring,
B ring and A ring. In contrast to earlier
results, it has been established that the epimerization of catechin
or epicatechin at C2, and the formation of catechinic acid in basic solution, may proceed through a
radical rather than ionic mechanism.
Crystal structure of Tetraaqua(ethylenediamine)nickel(II) sulfate dihydrate and of Tetraaqua(2,2'-bipyridyl)nickel(II) sulfate dihydrate
Authors: Healy PC , Patrick JM , White AH
Published: September 2010

The crystal structures of
the title compounds, [Ni(OH2)4(en)] [SO4].2H2O,
(1), and [Ni(OH2)4(bpy)]- [SO4].2H2O,
(2), have been determined by single-crystal X-ray diffraction methods at 295 K,
being refined by full matrix least-squares methods to residuals of 0.028,0.031
for 1852, 4323 independent 'observed' reflections respectively. Crystals of (1)
are monoclinic, C2/c, a 9.459(4), b 12.192(7), c 12.294(3) �, β 119.84(4)�, Z 4. In the cation, Ni-N is
2.061(2) �; Ni-O (trans to O, N respectively)
are 2.106(2), 2.063(2) �. Instead of being enlarged above 90� as predicted from
repulsion theory, the angle between the pair of oxygen atoms trans to nitrogen is diminished, being
87 14(7)�. Crystals of (2) are triclinic, P1, a 11.476(5), b 9.351(5), c 7.793(4) �, α 77.63(4), β
83.52(3), γ87.40(4)�, Z 2. In the
cation, Ni-N are both 2.063(2) �. Ni-O (trans
to N, O respectively) are 2.060(2), 2.O42(2); 2.O80(2), 2�. The short Ni-O
distance [2.042(2)�] is associated with the coordination of a trigonal water
molecule.
Ruthenium carbonyl complexes. III. Peparations, properties and structures of Dicarbonyl- and Monocarbonyl-(2,2':6',2''-terpyridyl)ruthenium(II) complexes
Authors: Deacon GB , Patrick JM , Skelton BW , Thomas NC , White AH
Published: September 2010

Reaction of 2,2':6',2''-terpyridyl
(tpy) with ruthenium dicarbonyl
dihalides yields the complexes Ru(CO)2X2(tpy) (X = Br or Cl), which can be protonated
giving [Ru(CO)2X2(tpyH)]ClO4. Crystal structures of the two forms
(red and yellow) of Ru(CO)2Br2(tpy) show each to have octahedral stereo-chemistry with cis-carbonyls, trans-bromines, and bidentate tpy.
Treatment of Ru(CO)2X2(tpy) complexes with trimethylamine
N-oxide in dichloromethane at room temperature gives cis-Ru(CO)X2(tpy) complexes. The presence of cis halogens and tridentate terpyridyl in
the chloro complex has been established by X-ray
crystallography. Reaction of terpyridyl with
ruthenium trichloride in dimethylformamide
yields trans-Ru(CO)Cl2(tpy), the crystal structure of which has been determined.
Anation and solvent exchange on (N,N-Dimethylformamide)[2,2',2''-tri(N,N-dimethylamino) triethylamine]nickel(II) and solvent exchange on Bis(N,N-dimethylformamide)-[2,2',2''-triaminotriethylamine]nickel(II)
Authors: Lincoln SF , Coates JH , Doddridge BG , Pisaniello DL
Published: September 2010

Anation of [Ni{N(CH2CH2NMe2)3}(OCHNMe2)]2+
by Br-, N3 - and NCS- is
characterized by rate laws consistent with the operation of an interchange
mechanism (1) and the small variation of k1 characterizing these
processes suggest that the activation mode is probably dissociative (d).
Typically for anation by NCS- ki(298.2K)
= 170 � 6 s-1, ∆H‡ = 44.0 � 2.1 kJ mol-1 and ∆S‡
=-54.7 � 7.2 JK-1 mol-1. The exchange of OCHNMe2
on [Ni{N(CH2CH2Nme2}3)-(OCHNMe2)]2+ is
characterized by kex(298.2 K)=203 � 20s-1,
∆H‡ = 42.6 � 2.0 kJ mol-1 and ∆S‡ = -58 � 8 JK-1
mol-1(if it is assumed that this is the only nickel(II) species
undergoing exchange) but the derivation of these parameters is complicated by
the presence of a minor species believed to be [Ni{N(CH2CH2NMe2)3}(0CHNMe2)2]2+.
Nevertheless the similarity of kex and ki observed for Br-, N3- and NCS- are consistent
with both OCHNMe2 exchange and anation on
[Ni {N(CH2CH2Nme2)3}(OCHNMe2)]2+ proceeding predominantly through an Id mechanism. For comparative purposes
0CHNMe2 exchange on [Ni{N(CH2CH2NHz)3}(OCHNMe2)2]2+,
which is characterized by kex(298.2 K) =
(1.4 � 0.2) × 105 and (1.9 � 0.9) × 107 s-1
for the non-equivalent OCHNMe2 sites, has also been studied.
The reduction of 3-substituted furans with lithium and ammonia
Authors: Massy-Westropp RA , Warren RFO
Published: September 2010

The reductions of 3-(1',1'-ethylenedioxynonyl)furan, 3-(1',1'-dimethoxynonyl)furan,
3-(1'-methoxynonyl)furan and 1-(furan-3'-yl)nonyl
acetate with lithium and ammonia are described. The products result from
benzylic type cleavage in the absence of an added proton source. When ethanol
is present during the reduction extensive saturation and fission of the furan
ring occurs.