M. Sarakha et G. Ferraudi, ELECTRON-TRANSFER REACTIONS OF RE(CO)(5) - ATOM-TRANSFER-CONCERTED MECHANISM VS BIMETALLIC INTERMEDIATE FORMATION, Inorganic chemistry, 35(2), 1996, pp. 313-317
Flash photochemically generated Re(CO)(5) reacts with halide complexes
, Cu(Me(4)[14]-1,3,8,10-tetraeneN(4))X(+), Cu(Me(2)pyo[l4]trieneN(4))X
(+), and Ni(Me(2)pyo[l4]trieneN(4))X(+) (X = Cl, Br, I) and ion pairs,
[Co(bipy)(3)(3+), X(-)]. The rate constants for the electron transfer
s have values, k approximate to 10(9) M(-1) s(-1), close to expectatio
ns for processes with diffusion-controlled rates. Reaction intermediat
es, probably bimetallic species, were detected in electron-transfer re
actions of Re(CO)(5) with Cu(Me(6)[14]dieneN(4))X(+), (X = Cl, Br, I).
In the absence of the halides X(-), the electron-transfer reactions b
etween Re(CO)(5) and these complexes are slow, k < 10(6) M(-1) s(-1).
The results are discussed in terms of inner-sphere pathways, namely an
atom-transfer-concerted mechanism. The mediation of bimetallic interm
ediates in the electron transfer is also considered.