M. Hofbauer et al., ION-PAIR CHARGE-TRANSFER COMPLEXES OF A DITHIOOXALATE ZINC DONOR COMPONENT WITH VIOLOGENS - SYNTHESIS, STRUCTURAL AND ELECTRONIC CHARACTERIZATION, Inorganica Chimica Acta, 247(2), 1996, pp. 147-154
Bipyridinium and phenanthrolinium accepters of different reduction pot
entials form with zinc 1,2-dithiooxalates (dto) ion-pair charge-transf
er complexes of the general formula {A(2+) [Zn(dto)(2)](2-)}. The cont
act ion pairs exhibit absorptions in the range 390-490 nm which can be
attributed to the ion-pair charge-transfer (IPCT) type. On the base o
f spectroscopic, electrochemical and quantum-chemical investigations t
he relation between optical and thermal electron transfer within the i
on pair applying the Hush theory is discussed. The mean reorganization
energy of 12 complexes is 180 kJ mol(-1) and exceeds the values found
for the dithiolene systems. Due to the diminished donor ability of th
e dithiooxalate unit, a hypsochromic shift of the position of the IPCT
band, compared with the metal dithiolenes, results. The extent of ele
ctron delocalization from [Zn(dto)(2)](2-) to PQ(2+), as described by
the parameter alpha(2), is calculated as 4.1 x 10(-6). X-ray analyses
of BQ[Zn(dto)(2)] and DP[Zn(dto)(2)] reveal that the solid-state struc
ture is largely determined by the geometry of the acceptor component.