pyridyl), 7.54 (dt, J = 3.0 Hz, 2H, Ar), 6.94 (dt, J = 2.0, 7.5 Hz,
4H, pyridyl), 6.79 (m, 6H, Ar and pyridyl), 6.59 (t, J = 6.0 Hz, 4H,
pyridyl), 3.87 (s, 8H CH2), 3.45 (s, 4H, CH2), 1.75 (s, 18H, But),
1.33 (s, 18H, But). 13C NMR (75.4 MHz, C6D6): d 156.2, 154.8,
151.9, 141.2, 137.0, 136.3, 125.9, 124.8, 123.6, 123.1, 121.7, 58.7,
56.1, 35.4, 34.4, 32.0, 30.1. Anal. Found: C, 52.42; H, 6.28; N,
6.17%. Calcd. for C54H70I2N6O2Cu2·2CH3OH: C, 52.54; H, 6.14;
N, 6.56%.
extract was dried over MgSO4, filtered, and concentrated under
=
reduced pressure. The presence of O PPh3 in the product mixture
was identified by GC/GC-MS analysis, using trans-stilbene oxide
as an internal standard with the following temperature profile:
injector temperature: 150 ◦C, initial column temperature: 150 ◦C
◦
(for 1 min), then increasing at a rate of 20 C min−1 to 250 ◦C
(maintained for 16 min). Retention times tR: PPh3, 13.2 min (m/z =
+
+
18
=
=
262, M ); O PPh3, 21.7 min (m/z = 278, M ); O PPh3, 21.7 min
+
=
(m/z = 280, M ). The ratio of O PPh3 : PPh3 in a product mixture
[Cu(L)(l-I)]2O2 (2). The complex was generated in situ by
bubbling dry oxygen gas into a stirring solution of [Cu(L)(l-I)]2
(1) in anhydrous CH2Cl2 for ∼10–20 min at 193 K. The reaction
mixture turned immediately from pale yellow to purple, and then
deep green. The concentrations of the precursor complex 1 used
in this study were 0.1–4 mM.
was also determined by 31P{ H} NMR.
1
Kinetics of the reaction between 2 and PPh3 in CH2Cl2 solutions
at 288 K have been studied by following the time dependence of the
absorbance at 334 nm due to 2. Complex 2 was prepared in situ by
the reaction of the precursor [Cu(L)(l-I)]2 (1) with dry oxygen (as
described above) in a reaction vessel equipped with a fiber-optic
quartz probe and a stir bar. The concentration of complex 1 was
kept at 0.1–0.2 mM. In a typical kinetic measurement, an aliquot
(5 mL) of a solution of 1 in CH2Cl2 was added to a reaction flask
containing 40–50 mL of degassed CH2Cl2, followed by bubbling
of a precooled oxygen gas through the solution for 10 min at 288 K
to accomplish the formation of 2. Then, an aliquot (0.5 mL) of a
solution of PPh3 in CH2Cl2 was introduced, via a cannula, into the
reaction mixture and the rate of the OAT reaction was monitored.
For anaerobic conditions, excess dioxygen in the reaction flask was
removed by purging argon gas into the solution for 20 min. During
the purging of argon gas, no spectral change of the solution was
observed. Analysis of the kinetic data was performed by using the
software Origin 6.0 Professional Microcal Software.
[Cu(PPh3)3I]·CH2Cl2 (3·CH2Cl2). A solution of 2 was gen-
erated in situ from [Cu(L)(l-I)]2 (1) (18 mg, 0.015 mmol) and
excess dioxygen at 193 K. A stream of argon gas was purged
into this solution at 193 K for 15 min to achieve an anaerobic
condition. A solution of excess PPh3 (39 mg, 0.15 mmol) in CH2Cl2
(1 mL) was added and the reaction mixture was stirred at 193 K
for another 10 min. The resulting green solution was allowed to
warm to room temperature, whereupon a pale yellow solution was
obtained. The solution was EPR silent at 77 K and its electronic
spectrum showed no absorption in the 350–900 nm region. Upon
standing the solution at room temperature for a few days, pale
yellow microcrystals of 3·CH2Cl2 were isolated (5 mg, 35%). The
product was washed with Et2O and dried in vacuo. Anal. Found:
C, 61.95; H, 4.50%. Calcd. for C54H45CuIP3·CH2Cl2: C, 62.19; H,
4.46%.
X-Ray crystallographic analysis
[Cu(L)Cl]Cl·2CHCl3 (4·2CHCl3). A solution of [Cu(PPh3)3I]
was obtained by the reaction of 2 with PPh3 in CH2Cl2 as
described above. Removal of all the volatiles in vacuo led to a
crude product, which was characterized by NMR spectroscopy:
Single crystals of the solvated complex 1·2CH2Cl2 were obtained
from a dichloromethane solution. Crystals suitable for crystal-
lographic studies were mounted in Lindemann glass capillaries
and sealed under nitrogen. Data were collected using graphite-
31
1
=
P{ H}NMR (500 MHz, CDCl3): d −5.3 (PPh3), 29.18 (O PPh3).
˚
monochromatized Mo-Ka radiation (k = 0.71073 A) on a Bruker
The crude product was dissolved in chloroform to give a yellow
solution. Standing the solution at room temperature for a few
weeks resulted in a color change from yellow gradually to green,
and from which green crystals were isolated. The compound was
washed with Et2O and dried in vacuo. The empirical formula of
the title compound was consistent with results obtained from
microanalysis. Anal. Found: C, 44.05; H, 4.72; N, 5.31%. Calcd.
for C27H35Cl2CuN3O·2CHCl3: C, 43.89; H, 4.78; N, 5.66%. The
SMART CCD diffractometer at 293 K using frames of oscillation
range 0.3◦, with 2.19◦ < h < 28.02◦. Diffraction measurements
for a single crystal of 4·2CHCl3 were carried out with a Bruker-
Nonius Apex CCD diffractometer at 100 K using graphite-
˚
monochromatized Mo-Ka radiation (k = 0.71073 A) and frame
of oscillation range 0.5◦, with 2.30◦ < h < 27.48◦. An empirical
absorption correction was applied using the SADABS program.30
The crystal structures were solved by the direct methods and
refined by full-matrix least squares on F2 using the SHELXTL
program package.31
◦
˚
selected bond distances (A) and angles ( ) for the complex are
summarized in Table S1.†
CCDC reference numbers 285531 and 286337.
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b513898a
Reaction of 2 with PPh3
In a typical experiment, complex 1 (12 mg, 0.01 mmol) was treated
with excess dioxygen at 193 K to afford the corresponding bis(l-
iodo)peroxodicopper(II) complex 2 as described above. To achieve
anaerobic conditions, the solution was purged with a stream of
argon for 15 min at 193 K. The solution was allowed to warm to
an appropriate temperature (243–288 K) for OAT experiments. A
solution of excess PPh3 (10 equiv. with respect to the precursor
complex 1 in CH2Cl2 (1 mL) was introduced to the solution
by a cannula and the reaction mixture was stirred for 3–18 h,
after which time the resulting mixture was quenched with 30%
ammonia, followed by a repetitive extraction with CH2Cl2. The
Acknowledgements
This work was supported by Academia Sinica and by grants from
the National Science Council (NSC 90-2113-M-001-006, 90-2113-
M-001-080 and 91-2113-M-006-006). The part of the work done
in Hong Kong was supported by a Direct Grant (A/C 2060271)
of The Chinese University of Hong Kong. We are grateful to Dr
Jyh-Fu Lee of the Research Division of the National Synchrotron
Radiation Research Center (NSRRC), Hsinchu, Taiwan for his
2242 | Dalton Trans., 2006, 2232–2243
This journal is
The Royal Society of Chemistry 2006
©
Pavlova, Svetlana V.
