Unprecedented π-Bonded Rhodio- and Iridio-o-Benzoquinones as Organometallic Linkers for the Design of Chiral Octahedral Bimetallic Assemblies

Abstract

We report the first synthesis of π-bonded rhodio and iridio-o-benzoquinones [Cp*M(o-benzoquinone)] (M = Rh (3a); M = Ir (3b)) following a novel synthetic procedure. These compounds were fully characterized by spectroscopic methods; in particular the X-ray molecular structure of 3b was determined. Compounds 3a,b were used as chelating organometallic linkers for the design of a new family of chiral octahedral bimetallic complexes, 4−9. The X-ray molecular structure of [(bpy)2Ru(3b)][OTf]2 (5) is presented and shows that the organometallic linker 3b is chelating the ruthenium center. In particular, the carbocycle of the organometallic linker 3b adopts a η4-quinone form, where the Cp*Ir is also bonded to only four carbons. Further our strategy to design new assemblies with organometallic linkers is successfully achieved. These assemblies hold promise for new properties relative to those made from organic bidentate ligands.

Charge photo-accumulation and photocatalytic hydrogen evolution under visible light at an iridium(iii)-photosensitized polyoxotungstate

“…In this context, we recently reported the synthesis and photophysical properties of a series of heteroleptic carbocyclometalated iridium(III)-polyoxometalate conjugates 41,42 following mild reaction conditions developed earlier by some of us. [43][44][45][46] In such complexes, photoinduced chargeseparated excited states of various lifetimes (ranging from nanoseconds to hundreds of nanoseconds) were observed by transient absorption spectroscopy. Most importantly, the functionalization of the heteroleptic cyclometalated iridium(III) on the picolinate ligand provides directionality to the photoinduced electron transfer by enhancing charge separation and delaying charge recombination, which is an asset for preventing reverse charge transfer from proceeding (equation 1).…”

Discovery, Structure, and Anticancer Activity of an Iridium Complex of Diselenobenzoquinone

“…(7,8) and the halogenated metal-arene compounds were prepared according to literature procedures. [10][11]14] Complex 9 was obtained as an orange microcrystalline powder (255 mg, 0.48 mmol Cytotoxicity study: The human A2780 ovarian cancer cell line was obtained from the European Collection of Cell Cultures (Salisbury, UK). Cells were grown routinely in RPMI medium containing glucose, 5 % foetal calf serum (FCS), and antibiotics at 37 8C and 5 % CO 2 .…”

“…[10] Both compounds were used as successful organometallic linkers to construct functional coordination assemblies. [11] Continuing our research into the stabilization of reactive intermediates, we sought to prepare a metal complex of pdiselenobenzoquinone. As mentioned before, the parent molecule p-diselenobenzoquinone 1 is unknown and has never been characterized even as an intermediate.…”

Planar Chiral Iridium Complexes with the Δ‐TRISPHAT Anion: Toward the First Enantiopure o‐Quinone Methide π‐Complex

“…Unlike the linear p-benzoquinone metal complexes the related o-benzoquinone compounds can be used as organometallic chelates "OM-chelates" to generate a new family of chiral octahedral bimetallic assemblies. [34][35][36][37] Hence, one would expect that with enantiopure o-quinone methide complexes in hand, it could be possible to generate a new class of optically active coordination assemblies.…”