Dithia[3.3]paracyclophane-bridged bimetallic ruthenium acetylide complexes: Synthesis, structures and influence of transannular π-π Interactions on their electronic properties

摘要

Two dithia[3.3]paracyclophane-bridged bimetallic ruthenium acetylide complexes 2 and 3, in which the upper deck of the cyclophanes were assembled with naphthalenyl and anthracenyl rings, have been designed and synthesized. X-ray crystal structures of 2 and 3 show that there are effective transannular π-π interactions between the two rings in the cyclophane unit. Electrochemistry studies revealed that the successive introduction of naphthalenyl and anthracenyl rings reduced the thermodynamic stability of the corresponding mixed-valence states of 2 and 3. Radical cations and dications of complexes 2 and 3 were generated after the addition of 1.0 or 2.0 equivalents of ferrocenium hexafluorophosphate ([FcH][PF_6]). The ν(CC) of radicals 2~+ and 3~+ shift 86 nm and 88 nm in contrast to 2 and 3, respectively. UV-Vis-NIR spectra of 2~+ and 3~+ exhibited three enveloped transitions in the NIR (10 000-4000 cm~(-1)) range. DFT studies showed that the compositions of the FMOs of 2 and 3 are more naphthalenyl and anthracenyl in character than the upper deck of complex 1. Spectroscopy and DFT studies indicated that the influence of transannular π-π interactions on the electronic transitions is more pronounced than in complex 1.