The <i>trans</i>–<i>cis</i> isomerisation of bis(dioxolene)bis(pyridine) ruthenium complexes

Tse, Yu-Hong; Auburn, Pamela R.; Lever, A. B. P.

doi:10.1139/v92-230

Cited by 8 publications

(5 citation statements)

References 16 publications

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“…The kinetically preferred isomer 1b is assigned as having the same overall geometry as 1a , but with the opposite orientation of the dioxolene ligand (oxygen meta to the tert -butyl groups trans to chloride) based on the negligible changes in the optical spectrum when 1b isomerizes to 1a (Figure S29). Were the central chromophore different in the two isomers, significant changes in the optical spectrum would be expected, as seen for example in previous examples of cis- and trans- bis(iminoxolene) , or -bis(dioxolene) metal complexes. In principle, the alkyne could be free in 1b and the compound could adopt a five-coordinate, square pyramidal structure analogous to that observed for the bis(iminoxolene) complex (Diso) 2 IrCl.…”

Section: Resultsmentioning

confidence: 87%

Slicing the π in Three Unequal Pieces: Iridium Complexes with Alkyne, Iminoxolene, and Dioxolene Ligands

Haungs

Brown

2022

Organometallics

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The formally isoelectronic alkyne, iminoquinone, and benzoquinone ligands can all exhibit significant metal−ligand π bonding. Condensation of 2,6-bis(triisopropylsilylethynyl)aniline with 3,5-di-tert-butyl-1,2-benzoquinone affords a ligand with two such moieties, the alkyne-containing iminoquinone Tipsi. All three groups are installed around a single iridium center by successive treatment of [(coe) 2 IrCl] 2 with Tipsi and 3,5-di-tert-butyl-1,2benzoquinone to give (κ 2 ,η 2 -Tipsi)(3,5-t Bu 2 Cat)IrCl in two isomeric forms with cis iminoxolene and dioxolene groups and a bound alkyne. Structural, spectroscopic, and computational data indicate that the dioxolene and especially the iminoxolene are strongly engaged in π bonding but that the alkyne is not an effective π donor or acceptor. Pyridine displaces the bound alkyne in (κ 2 ,η 2 -Tipsi)(3,5-t Bu 2 Cat)IrCl to give two isomers of (κ 2 -Tipsi)(3,5-t Bu 2 Cat)Ir(py)Cl, both with the iminoxolene and dioxolene trans to each other. The reaction rates and modest stereospecificity of the dissociative substitution reaction are consistent with a mechanism with competitive, stereochemically distinct, pathways for forming square pyramidal intermediates, which rapidly isomerize to the trans isomer before irreversible trapping by pyridine. The five-coordinate intermediates funnel down to the trans isomer because it is stabilized by an additional metal−ligand π interaction that is not possible in the cis isomers.

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Section: Resultsmentioning

confidence: 87%

Slicing the π in Three Unequal Pieces: Iridium Complexes with Alkyne, Iminoxolene, and Dioxolene Ligands

Haungs

Brown

2022

Organometallics

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“…We have recently been concerned − with the electronic properties of the ruthenium complexes of the noninnocent quinonoid systems with (O,O), (NH,O), (NH,NH), and recently (NH,S) coordinating atoms. Our interest has lain with studies of the extent of coupling between metal dπ and ligand π and π* levels as a function of the net oxidation state of the system.…”

Section: A Introductionmentioning

confidence: 99%

Binuclear 1,2,4,5-Tetraimino-3,6-diketocyclohexane Bis[bis(Bipyridine)ruthenium(II)] Redox Series

et al. 1999

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The reaction of the [Ru(bpy)2(MeOH)2]2+ cation (bpy = 2,2'-bipyridine) with 1,2,4,5-tetraaminobenzene in the presence of trace water and oxygen yields the cation [(bpy)2Ru(1,2,4,5-tetraimino-3,5-diketocyclohexane)Ru(bpy)2]4+. This binuclear species undergoes ligand-based reductions, giving the 3+ and 2+ charged species. The X-ray structure, electrochemistry, ZINDO calculations, and NMR, ESR, UV/vis, and IR spectra were analyzed where possible, giving an electronic model of the binuclear species and some of its redox products. The X-ray structure reveals the [(bpy)2Ru] fragments symmetrically disposed across the 1,2,4,5-tetraimino-3,5-diketocyclohexane bridge in a molecule with Cs symmetry.

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“…The existence of a peak at 612 nm in the spectrum indicates that the complex is a cw-diphosphine isomer. 13 The cis disposition of the PR3 ligands maybe stabilized by hydrophobic interactions between bulky alkyl chains of the phosphine. A similar cis arrangement has been reported, 46 for Ru (PPhg) 2(DTBSq)2, in which intramolecular -interactions between the phosphine phenyl rings and the rings of the quinone ligands were noted.…”

Section: Resultsmentioning

confidence: 99%

“…Metal complexes containing dioxolene ligands (dioxo members of the catechol-quinone redox series) have been the subject of many recent publications.1-9 The coordination of two "noninnocent" ligands on one transition metal ion provides especially useful insight into metal-ligand bonding, intramolecular electron transfer, and the concept of oxidation state in coordination chemistry. We have recently reported electrochemical and spectroscopic data for redox series based upon Rufbpyh-(dioxolene)2, Ru(py)4(dioxolene)2,10'u Ru(R-py)2(dioxolene)2, 12,13 and Ru(R-P)2(dioxolene)214 where R-P are variously substituted phosphines and phosphites.…”

Section: Introductionmentioning

confidence: 99%

In-situ Langmuir-Blodgett surface film electrochemical study of Ru(P(C18H37)3)2(DTBSq)2

Fu¹,

Ouyang²,

Lever³

1993

J. Phys. Chem.

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Electronic spectroscopic and electrochemical data are presented for R U ( P ( C I~H~~)~) Z ( D T B S~)~ (DTBSq = 3,5-di-terf-butyl-o-benzosemiquinonate). The compound contains "non-innocent" dioxolene ligands (dioxolene refers to any of the series catechol-semiquinone-quinone), which show rich electrochemical and spectroscopic properties. The long alkyl chains attached to the phosphine ligands permit the casting of organized LangmuirBlodgett (LB) films which were electrochemically characterized as the free standing film in-sifu in the LangmuirBlodgett trough. One reversible film oxidation wave was observed with an indium doped tin oxide electrode touching (horizontally) the floating Langmuir-Blodgett film on the subphase surface. Interactions between the electroactive monolayers and redox species in the subphase are probed using cyclic voltammetry. Evidence is presented for direct interaction of the surface film and subphase species.

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The trans–cis isomerisation of bis(dioxolene)bis(pyridine) ruthenium complexes

Cited by 8 publications

References 16 publications

Slicing the π in Three Unequal Pieces: Iridium Complexes with Alkyne, Iminoxolene, and Dioxolene Ligands

Slicing the π in Three Unequal Pieces: Iridium Complexes with Alkyne, Iminoxolene, and Dioxolene Ligands

Binuclear 1,2,4,5-Tetraimino-3,6-diketocyclohexane Bis[bis(Bipyridine)ruthenium(II)] Redox Series

In-situ Langmuir-Blodgett surface film electrochemical study of Ru(P(C18H37)3)2(DTBSq)2

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