The Synthesis of Dimeric ReI-Phenylenediimine Conjugates: Spectroscopic and Electrochemical Studies

• Published in: European journal of inorganic chemistry Vol. 2014; no. 16; pp. 2643 - 2652
• Main Authors: Hasheminasab, Abed, Engle, James T., Bass, Jacob, Herrick, Richard S., Ziegler, Christopher J.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01-06-2014; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Bridging ligands; Cyclic voltammetry; Dimers; Rhenium; UV/Vis spectroscopy
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201400076

A series of dimeric ReI(CO)3 compounds have been prepared by means of a one‐pot reaction of [Re(CO)5X] (X = Cl, Br), pyridine‐2‐carboxyaldehyde, and o‐, m‐, or p‐phenylenediamine. For the m‐ and p‐substituted phenylenediamine reactions, phenyl‐bridged bis(pyridine‐2‐carbaldimine) compounds of the formula [Re(CO)3X]2(μ‐PPC) [3–7; X = Cl, Br; μ‐PPC = m‐ or p‐phenylene bis(pyridine‐2‐carbaldimine)] were produced, with m‐phenylenediamine forming a mixture of isomers. For reactions with o‐phenylenediamine, multiple products formed (compounds 8–11), which ranged from the desired o‐phenylene bis(pyridine‐2‐carbaldimine) adduct to 2‐pyridylbenzimidazole and bridging dipyridinylquinoxaline complexes. An example of each complex was structurally elucidated by single‐crystal X‐ray methods. The dimeric m‐ and p‐phenylene‐bridged Re(CO)3X compounds, including a sulfonate derivative designed to improve solubility, were investigated for possible photophysical applications through the use of UV/Vis spectroscopy and cyclic voltammetry; the study revealed coupling between the rhenium centers.
A series of phenylene‐bridged dimeric Re(CO)3 complexes have been prepared by means of metal‐mediated one‐pot reactions through Schiff base condensation. New structures were elucidated by X‐ray crystallography. UV/Vis absorption spectra show strong metal‐to‐ligand charge transfer (MLCT). Cyclic voltammetry confirmed that the bridging phenylene unit mediates coupling between the Re(CO)3X centers.