Inorg. Chem. 1986, 25, 1505-1506 partly from the fact that a specific ligand such as chloride would not be expected to have a constant value as L is changed. The difference between the AOM parameters for the ligands studied to date are outside of the uncertainty limits. In summary, the relative position of triethylphosphine in the two-dimensional spectrochemical series for the PtC13Ln-series is as follows: for u donors, PEt3 > NMe3 > C2H4 > C1- > Br-; for K donors, NMe, > C1- > PEt3 > CzH4. Acknowledgment. The authors thank Lee Tutt for preliminary measurements and the National Science Foundation for financial support. Registry No. (Pr4N)[PtC13PEt3], 19508-37-3.
1505
.30-
OD .I 5 -
0 '
350
550
450
,1
I o
Figure 1. Spectrum of CuCH,',,
Contribution from the Nuclear Research Centre Negev and Coal Research Center and the Chemistry Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Kinetics of Formation and Decomposition of the Methyl-Copper(I1) Complex in Aqueous Solutions. A Pulse-Radiolysis Study
measured 10 ps after the pulse: N20-saturated solution containing 9 X M CuSO,, 2 X M Cr,?, and 0.09 M (CH3),S0at pH 3.9; pulse intensity 1500 rad/pulse. (CH3)2S0in the pH range 0.7-5.0 were irradiated by 0.3-1.5 pulses of 200-mA 5-MeV electrons. The experimental setup was identical with that described earlier in detail.3 The pulse intensity was 800-3000 rad. At pH 23.0the following reactions as well as reaction 412 have to be considered: ps
Haim Cohen*+ and Dan Meyerstein**
H 2 0 2 e,;,
Received July 31, 1985
ea,-
The effect of copper ions on the product composition in cataltyic free-radical processes in aqueous solutions was interpreted as indicating that short-lived intermediates with copper-arbon bonds are formed in these Recently it was shown that indeed reactions 1 and 2 can be followed in aqueous solutions by
.OH, -H, H2, H 2 0 2 ,H30+,,
H20
+ N,O
ea,-
+ Cu2+,,
Cu',,
-H
+ CU',,
5 X lo9 < k
CUH',,
k = 3.1
Cu2+,,
+ Cr2+,,
-
Cu+,,
+ CrllIaq
(3)
By use of this reaction, solutions containing [Cu+,,]/[Cuz+,,] < 0.2 can be easily prepared and kept for several hours.' As k2 is in many systems over two-orders of magnitude larger than k , , reaction (2) can be directly followed. (The reactions of CrlIIaq with aliphatic free radicals are very slow.)' As the methyl radical is the simplest aliphatic free radical and the properties of other free radicals are compared to it, we decided to study the reaction The corresponding reaction with Cu2+,,. is extremely The properties of [Cui1-CH3J+ were earlier studied applying the flash-photolytic technique:? However the limitations of the technique did not enable a detailed kinetic study or product analysis. Nitrous oxide saturated solutions containing (5-30) X M CuSO,, (2-20) X M, Crl*Iaqand Cu+,,, and 0.1-1.0 M Nuclear Research Centre Negev and Coal Research Center. 1Chemistry
Department.
0020-1669/86/1325-1505$01.50/0
.OH
-+
1010 M-I scl
CU",,
+ H2 + OH-,,
X
(6)
X +
(7)
CuH+,, l o i o M-I s-I1O
+ (CH3)ZSO k = 7.0
X
