Synthesis and Characterization of Novel Re(BIAN)(CO)₃Cl Derivatives Including the First Example of a Water-soluble Tricarbonyl Rhenium(I) Complex with Bis(imino)acenaphthene Ligands

Abstract

A series of rhenium(I) carbonyl chloride complexes carrying bis(imino)acenaphthene (BIAN) molecules as p-acceptor ligands was prepared and characterized by various spectroscopic techniques. Among the novel compounds described, the remarkable example of a deeply colored water-soluble rhenium carbonyl derivative is presented. The crystal structures of this family of BIAN compounds are also reported, which confirm the position of the chloro ligand at the tricarbonyl rhenium(I) center. In the case of BIAN ligands carrying bulky substituents in the ortho-position of the arylimino subunits, evidence has been found for an exchange of the halide ligand in solution, which is considered to be of major relevance for catalytic applications. Implications of our results for the fields of photocatalytic CO2 reduction and the controlled release of the gasotransmitter CO in aqueous solution are briefly discussed.

Two‐Electron Carbon Dioxide Reduction Catalyzed by Rhenium(I) Bis(imino)acenaphthene Carbonyl Complexes

“…[14, 27] The rhenium complex 1 was synthesized as previously reported. [14] General procedure for the preparation of 2 and 3 :[28] Equimolar amounts of Re(CO) 5 Cl (0.05 g, 0.14 mmol) and the corresponding bis(arylimino)acenaphtene ligand were refluxed in dry toluene (4 mL) for 30 min. Complete precipitation of the product was obtained upon cooling the reaction mixture to room temperature and slow addition of n -hexane.…”

“…[23] Electrochemical studies and product gas analysis up to now suggest that the reaction cycle of our new catalysts 2 and 3 proceeds in a similar way, and that the release of the chloro ligand might be directly influenced by the aryl group substituents of the BIAN-R ligands. [28]…”

“…In summary, we successfully test and fully characterize the electrocatalytic properties of rhenium(I) tricarbonyl complexes carrying bis(arylimino)acenaphthene (BIAN) ligands[14, 28] for the selective two-electron reduction of CO 2 to CO in homogeneous solution. A variation of the ligand substitution pattern in close proximity to the metal center is demonstrated to have a very significant influence on the catalytic performance of these systems.…”

Hydrophilic CO-Releasing Material of PEGlyated Ruthenium Carbonyl Complex

“…Although a few ionic transition metal carbonyl complexes are water-soluble, the CO release tests indicated that the M-CO bonds of simple ionic CO-RM degraded quickly under complicated physiological conditions and produced unpredictable side effects, such as blocking blood vessels and causing cytotoxic effects. Increasing the water-solubility and finely controlling the CO release kinetics of transition metal complexes are challenges in therapeutic CO-RMs [ 11 , 12 , 13 , 14 , 15 ].…”

Synthesis, Electronic Structure and Interaction of Rhodium(I) and Iridium(I) Bisimine-Acenaphthalene Complexes with Co2

“…It has been reported that imines are electrochemically active in the presence of CO 2 [19], and that CO 2 electroreduction occurs as part of an inner sphere electron transfer mechanism [20]. Thus, more recent applications of BIAN ligands have looked into the ever growing field of CO 2 reduction, with Re(I)BIAN carbonyl complexes reported which catalysed a two-electron CO 2 photocatalytic reduction [21], as well as a Rh(III)BIAN complex which has shown CO 2 electrocatalytic reduction ability following its in situ reduction to the Rh(I) oxidation state [22,23]. Before these studies, Rh(I)BIAN complexes were reported as part of synthetic [24,25] or catalytic studies [26,27], while reactivity with the solvent acetonitrile complicated electrochemical analyses of the single five-coordinate complex previously reported [22,23].…”