A Diruthenium Complex of a “Nindigo” Ligand

Mondal, Prasenjit; Ehret, Fabian; Bubrin, Martina; Das, Amit; Mobin, Shaikh M.; Kaim, Wolfgang; Lahiri, Goutam Kumar

doi:10.1021/ic400390b

Cited by 32 publications

(18 citation statements)

References 57 publications

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“…Reaction of N,N '‐diphenylimine‐indigo with Ru(acac) 2 resulted in the formation of a diruthenium complex with the nindigo bridge in the neutral leuco form [(acac) 2 Ru(leuco‐nindigo)Ru(acac) 2] (Scheme ).This structure is supported by the relatively long central C–C bond …”

Section: Indigodiimine (“Nindigo”) As a Complex Ligandmentioning

confidence: 99%

Metal Complexes of Indigo and of Some Related Ligands

Beck

Sünkel

2020

Zeitschrift anorg allge chemie

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While the first coordination compounds of indigo were reported over 100 years ago, a systematic study of the coordination chemistry of this important dye and also its structural “relatives” remained silent for over half a century. Only in the last two decades of the 20th century research on this topic started again keeps on growing ever since. It could be established, mainly by X‐ray crystallography, but also by many other modern spectroscopic techniques, that deprotonated indigo, and its deprotonated oxidized and reduced forms act as mono‐ and bidentate chelate ligands in metal complexes

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Section: Indigodiimine (“Nindigo”) As a Complex Ligandmentioning

confidence: 99%

Metal Complexes of Indigo and of Some Related Ligands

Beck

Sünkel

2020

Zeitschrift anorg allge chemie

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“…Guided by the better understanding of the isomerization, people can synthesize alternate, more efficient indigoid dyes with various properties, for example, solubilities, colors, durabilities, capabilities as chemical indicators, etc. Also, the two N(indole)CCCN(imine) moieties in the indigo diimine ( 2 , called “Nindigo” by Hicks and co-workers) are similar to β-diketiminates (NacNacs), and hence it is a promising binucleating ligand. − However, once it adopts a cis configuration, the two identical binding sites convert to one with two imine N atoms and one with two indole N atoms, which exhibit different coordination properties. , Therefore, the protoisomerization provides a measure to adjust the ligation capability of Nindigo through tuning the acidity of the environment. This versatility in coordination chemistry reflects Nindigo’s potential of being a switchable π-system .…”

Section: Introductionmentioning

confidence: 99%

A Computational Study of the Protoisomerization of Indigo and Its Imine Derivatives

2016

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The protoisomerization (isomerization induced by protonation) mechanisms of indigo as well as indigo di- and monoimine derivatives were investigated using computational chemistry. Both density functional theory (M06-2X) and wave function theory (GMC-QDPT) methods were used to obtain reliable results. A solvation model (C-PCM with CH2Cl2 solvent) was employed to mimic the actual environment of the isomerization. The calculations reveal that the protoisomerizations of both the indigo and its imine derivatives are thermodynamically favorable. However, the energy barriers for rotating the double bonds in the derivatives are found to be lower than the one for indigo. More importantly, the imine derivatives undergo one-step isomerization, whereas a two-step process is predicted for indigo itself. The computational results provide insightful explanation for the different protoisomerization propensities of the parent indigo and its imine derivatives observed in experiment.

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“…5 While boron(III) 6,7 and palladium(II) 5,7 are not expected to undergo one-electron transfers easily in conjunction with redox-active ligands such as Nindigo, it has been shown that the Co and Ru compounds involve redox-active metals. 4,8,9 One of the most widely employed 2a,3,10,11 ruthenium complex fragments is [Ru(bpy) 2 ] n+ , which we have now tried to combine with the Nindigo ligand indigo-bis(N-phenylimine). In the course of these investigations, we obtained the first example of cisconfigured Nindigo as an asymmetrically bis-chelating and redoxactive bridge.…”

Section: ■ Introductionmentioning

confidence: 99%

UncommoncisConfiguration of a Metal–Metal Bridging Noninnocent Nindigo Ligand

et al. 2014

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In contrast to several reported coordination compounds of trans-Nindigo ligands [Nindigo = indigo-bis(N-arylimine) = LH2] with one or two six-membered chelate rings involving one indole N and one extracyclic N for metal binding, the new diruthenium complex ion [(acac)2Ru(μ,η(2):η(2)-L)Ru(bpy)2](2+) = 2(2+) exhibits edge-sharing five- and seven-membered chelate rings in the first documented case of asymmetric bridging by a Nindigo ligand in the cis configuration [L(2-) = indigo-bis(N-phenylimine)dianion]. The dication in compound [2](ClO4)2 displays one Ru(α-diimine)3 site and one ruthenium center with three negatively charged chelate ligands. Compound [2](ClO4)2 is obtained from the [Ru(bpy)2](2+)-containing cis precursor [(LH)Ru(bpy)2]ClO4 = [1]ClO4, which exhibits intramolecular H-bonding in the cation. Four accessible oxidation states each were characterized for the 1(n) and 2(n) redox series with respect to metal- or ligand-centered electron transfer, based on X-ray structures, electron paramagnetic resonance, and ultraviolet-visible-near-infrared spectroelectrochemistry in conjunction with density functional theory calculation results. The structural asymmetry in the Ru(III)/Ru(II) system 2(2+) is reflected by the electronic asymmetry (class I mixed-valence situation), leaving the noninnocent Nindigo bridge as the main redox-active site.

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A Diruthenium Complex of a “Nindigo” Ligand

Cited by 32 publications

References 57 publications

Metal Complexes of Indigo and of Some Related Ligands

Metal Complexes of Indigo and of Some Related Ligands

A Computational Study of the Protoisomerization of Indigo and Its Imine Derivatives

UncommoncisConfiguration of a Metal–Metal Bridging Noninnocent Nindigo Ligand

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