The donor−acceptor complex [(O,NQ2−)Pt-
(pap0)] (1; pap = phenylazopyridine, O,NQ0 = 4,6-di-tertbutyl-
N-phenyl-o-iminobenzoquinone), which displays strong
π-bonding interactions and shows strong absorption in the
near-IR region, has been investigated with respect to its redoxinduced
reactivity and electrochemical and excited-state
properties. The one-electron-oxidized product [(O,NQ•−)Pt-
(pap0)](BF4) ([1]BF4) was chemically isolated. Single-crystal
X-ray diffraction studies establish the iminosemiquinone form
of O,NQ in [1]+. Simulation of the cyclic voltammograms of 1
recorded in the presence of PPh3 elucidates the mechanism
and delivers relevant thermodynamic and kinetic parameters
for the redox-induced reaction with PPh3. The thermodynamically
stable product of this reaction, complex [(O,NQ•−)
Pt(PPh3)2](PF6) ([2]PF6), was isolated and characterized by X-ray crystallography, electrochemistry, and electron paramagnetic
resonance spectroscopy. Picosecond time-resolved infrared spectroscopic studies on complex 1b (one of the positional isomers
of 1) and its analogue [(O,OQ2−)Pt(pap0)] (3; O,OQ = 3,5-di-tert-butyl-o-benzoquinone) provided insight into the excited-state
dynamics and revealed that the nature of the lowest excited state in the amidophenolate complex 1b is primarily diimine-ligandbased,
while it is predominantly an interligand charge-transfer state in the case of 3. Density functional theory calculations on
[1]n+ provided further insight into the nature of the frontier orbitals of various redox forms and vibrational mode assignments.
We discuss the mechanistic details of the newly established redox-induced reactivity of 1 with electron donors and propose a
mechanism for this process.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)