Inorganic Chemistry
Article
system. H and 13C nuclear magnetic resonance (NMR) spectra were
1
obtained on a Bruker AVA 500 or 600 spectrometer as solutions in
CDCl . Chemical shifts (δ’s) are reported in parts per million (ppm)
3
relative to the residual solvent (δH 7.26 and δC 77.0). Mass spectra
were recorded on a MAT 900 XP spectrometer (EI) or a Thermo-
Fisher LCQ Classic (ESI). Elemental analyses were determined by Mr.
Stephen Boyer at London Metropolitan University, School of Human
Sciences, Science Centre, London Metropolitan University, 29
Hornsey Road, London, N7 7DD. Crystal structure data (CCDC-
1
406119) were collected at 150 K on a three circle Rigaku Oxford
Diffraction SuperNova CCD diffractometer equipped with an Oxford
Cryosystems low temperature device with Cu Kα radiation (λ =
1
.541 78 Å). The new reagents L1, L3, and L5 were prepared by
23
adaptation of methods described previously.
N-Benzyl-3-(benzyl(phenyl)amino)-N-phenylpropanamide
L1). Neat 3-bromopropanoyl chloride (18.7 g, 109 mmol) was added
(
dropwise to a stirred solution of N-benzylaniline (38.5 g, 210 mmol) in
CH Cl (200 mL) at 0 °C and then stirred at room temperature for 1
Figure 1. Tripodal amidoamines which have been used as
chloridometalate extractants and the five-, six-, and seven-membered
2
2
h. The resulting mixture was filtered; N-benzylaniline (37.3 g, 204
mmol) was added to the filtrate, and the mixture refluxed for 3 h. After
filtration and evaporation of solvent, the resulting oil purified on a
silica column, eluting with 20% chloroform in hexane to give the title
“proton chelates” which can be formed during metal extraction by the
protonated reagents.
1
6
compound as a pale yellow/green oil, yield 14.5 g (32%). H NMR
chloridometalate species. This is very clearly demonstrated by
(
δ , 500 MHz, CDCl ) 6.56−7.34 (m, 20H, aromatic H), 4.91 (s, 2H,
2−
H
3
the X-ray crystal structure of a ZnCl4 assembly in which the
13
CH ), 4.46 (s, 2H, CH ), 3.60 (t, 2H, CH ), 2.50 (t, 2H, CH ).
C
2
2
2
2
receptor site directs four polarized C−H and N−H groups
NMR (δ , 125 MHz, CDCl ) 171.2, 137.3, 129.7, 129.3, 128.9, 128.5,
C
3
2−
toward the edges and the center of a face of the ZnCl
+
4
128.4, 128.1, 127.4, 54.3, 53.6, 47.7, 32.0. m/z (ESI) 421.92 (M+H ).
N-(2-Ethylhexyl)prop-2-enamide. Neat 2-ethylhexylamine (6
mL, 37 mmol) was added dropwise to a stirred solution of acryloyl
1
8
tetrahedron. This work examines whether structurally
analogous amidoethers can function in a similar manner. A
potential advantage of these latter reagents is that their lower
basicity might make it easier to subsequently release the
chloridometalate species, allowing them to be stripped by
contacting the loaded organic phase with water, generating
chloroplatinic acid as in eq 4.
chloride (3 mL, 37 mmol) in dry CH Cl (20 mL) at 0 °C. After
2 2
stirring for 30 min at room temperature, the reaction was quenched
with saturated sodium hydrogen carbonate solution (3 × 30 mL) and
the organic phase washed with water (30 mL) and dried over MgSO4.
The solvent was evaporated under vacuum to give the title compound
as a colorless oil which was used without further purification in the
1
preparation of L3, yield 4.84 g (72%). H NMR (δ , 600 MHz,
[
(LH) PtCl ] ⇌ H PtCl + 2L
H
2
6 org
2
6
org
(4)
CDCl ) 6.29 (dd, 1H, HCCH ), 6.12 (dd, 1H, CCH′H), 5.64
3
2
To this end, a hydrocarbon-soluble amidoether reagent L5
(dd, 1H, CCH′H), 3.34−3.26 (m, 2H, CH
2
NH), 1.52−1.48 (m,
1
H, CH), 1.38−1.27 (m, 8H, CH and CH ), 0.95−0.88 (m, 6H, CH ).
(
Figure 2) with a 2-ethylhexyl substituent at site R , along with
2
3
2
1
3
C NMR (δ , 125 MHz, CDCl ) 165.7, 131.0, 126.1, 42.5, 39.4, 31.0,
C
3
2
8.9, 24.3, 23.0, 14.1, 10.9.
N-(2-Ethylhexyl)-3-(methylphenylamino)-propanamide (L3).
A mixture of N-(2-ethylhexyl)prop-2-enamide (4.0 g, 22 mmol), N-
methylaniline (2.6 g, 24 mmol), and SiCl (2 mol %) was stirred and
4
heated under N at 70 °C for 16 h. The mixture was dissolved in
2
CH Cl (20 mL), washed with water (3 × 20 mL), and dried over
2
2
MgSO . The solvent was removed and the crude product purified on a
4
silica column, eluting with 10% methanol in CH Cl to give the title
2
2
1
compound as a pale yellow oil, yield 4.1 g (65%). H NMR (δ , 600
H
MHz, CDCl ) 7.28−7.26 (m, 2H, aromatic H), 6.79−6.76 (3H,
3
aromatic H), 3.69 (t, 2H, CH N(CH )), 3.2 (m, 2H, CH NH), 2.95
2
3
2
(
s, 3H, NCH ), 2.44 (t, 2H, CH CH N(CH )), 1.42−1.38 (m, 1H,
3
2
2
3
13
CH), 1.31−1.20 (m, 8H, CH ), 0.93−0.86 (m, 6H, CH ). C NMR
(
2
3
δ , 151 MHz, CDCl ) 171.5, 148.9, 129.3, 117.2, 113.1, 49.4, 42.4,
C 3
3
9.3, 38.8, 34.1, 31.0, 28.9, 24.2, 23.0, 14.1, 10.8. m/z (ESI) 290.2 (M
+
+
H ).
-Phenoxypropanoic Acid. A mixture of 3-phenyoxynitrile (9.88
g, 67 mmol) in 6 M HCl (50 mL) was heated at reflux temperature for
6 h. After being cooled, the mixture was filtered and the precipitate
Figure 2. Amidoamine (L1−L4) and amidoether (L5−L6) reagents
discussed in this work.
3
1
two amidoamine analogues (L1 and L3) have been prepared in
this work to compare their extraction properties. Density
functional theory (DFT) calculations were undertaken with
shorter chain, n-butyl analogues, L2, L4, and L6, and with the
more conformationally rigid L1, which also afforded crystals of
recrystallized from 40:60 benzene/petroleum ether (60−80 °C) to
1
give the title compound as colorless crystals, yield 6.95 g (62%). H
NMR (δ , 500 MHz, CDCl ) 7.36−7.31 (m, 2H, aromatic H), 7.06−
H
3
7
2
1
.02 (m, 1H, aromatic H), 6.96−6.92 (m, 1H, aromatic H), 4.23 (t,
13
H, CH ), 2.86 (t, 2H, CH ). C NMR (δ , 125 MHz, CDCl ) 177.4,
2
2
C
3
58.4, 129.5, 121.2, 114.7, 63.0, 34.4.
-Phenoxypropanoyl Chloride. A mixture of 3-phenoxypropa-
[
(L1H) PtCl ] suitable for X-ray structure determination.
2 6
3
noic acid (5.80 g, 35 mmol) and thionyl chloride (4.5 mL, 62 mmol)
was stirred at room temperature for 3 h. Excess thionyl chloride was
removed by vacuum distillation to give the title compound as an
orange oil which was used in the preparation of L5 without further
EXPERIMENTAL SECTION
All solvents and reagents were used as received from commercial
suppliers. Deionized water was obtained from a Milli-Q purification
■
B
Inorg. Chem. XXXX, XXX, XXX−XXX