1 research outputs found
Interligand Charge Transfer in a Complex of Deprotonated <i>cis</i>-Indigo Dianions and Tin(II) Phthalocyanine Radical Anions with Cp*Ir<sup>III</sup>
A diamagnetic complex,
{(<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup>(Cp*Ir<sup>III</sup>)} (<b>1</b>), in
which deprotonated <i>cis</i>-indigo dianions coordinate
an iridium center through two nitrogen atoms was obtained. By employment
of the ability of the iridium center in <b>1</b> to coordinate
an additional ligand, the complex [(Bu<sub>4</sub>N<sup>+</sup>)<sub>2</sub>{[Sn<sup>II</sup>(Pc<sup>•3–</sup>)]Â(<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup>Cp*Ir<sup>III</sup>}<sup>•–</sup><sub>2</sub>·0.5Â(H<sub>2</sub>Indigo)·2.5C<sub>6</sub>H<sub>4</sub>C<sub>l2</sub> (<b>2</b>), which has two functional ligands coordinating an Ir<sup>III</sup> center, was obtained. This complex has a magnetic moment
of 1.71 μ<sub>B</sub> at 300 K, in accordance with an <i>S</i> = 1/2 spin state. The spin density is mainly delocalized
over the Pc<sup>•3–</sup> macrocycle and partially on
(<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup>. Due to an effective π–π
interaction, a thermally activated charge transfer from [Sn<sup>II</sup>(Pc<sup>•3–</sup>)]<sup>•–</sup> to (<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup> is observed, with an estimated Gibbs energy (−Δ<i>G</i>°) of 9.27 ± 0.18 kJ/mol. The deprotonation of
indigo associated with the coordination of Ir<sup>III</sup> by the
indigo releases H<sup>+</sup> ions, which protonate noncoordinating
indigo molecules to produce leuco <i>cis</i>-indigo (H<sub>2</sub>Indigo). One H<sub>2</sub>indigo links two (<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup> dianions in <b>2</b> to produce strong N–H···OC
and O–H···OC hydrogen-bonding interactions