Issue 34, 2018

Bridging cyanides from cyanoiron metalloligands to redox-active dinitrosyl iron units

Abstract

Cyanide, as an ambidentate ligand, plays a pivotal role in providing a simple diatomic building-block motif for controlled metal aggregation (M–CN–M′). Specifically, the inherent hard–soft nature of the cyanide ligand, i.e., hard-nitrogen and soft-carbon centers, is due to electronic handles for binding Lewis acids following the hard–soft acid–base principle. Studies by Holm and Karlin showed structural and electronic requirements for cyanide-bridged (por)FeIII–CN–CuII/I (por = porphyrin) molecular assemblies as biomimetics for cyanide-inhibited terminal quinol oxidases and cytochrome-C oxidase. The dinitrosyliron unit (DNIU) that exists in two redox states, {Fe(NO)2}9 and {Fe(NO)2}10, draws attention as an electronic analogy of CuII and CuI, d9 and d10, respectively. In similar controlled aggregations, L-type [(η5-C5R5)Fe(dppe)(CN)] (dppe = diphenyl phosphinoethane; R = H and Me) have been used as N-donor, μ-cyanoiron metalloligands to stabilize the DNIU in two redox states. Two bimetallic [(η5-C5R5)(dppe)FeII–CN–{Fe(NO)2}9(sIMes)][BF4] complexes, Fe-1 (R = H) and Fe*-1 (R = CH3), showed dissimilar FeIIC[triple bond, length as m-dash]N–{Fe(NO)2}9 angular bends due to the electronic donor properties of the [(η5-C5R5)Fe(dppe)(CN)] μ-cyanoiron metalloligand. A trimetallic [(η5-C5Me5)(dppe)FeII–CN]2–{Fe(NO)2}10 complex, Fe*-2, engaged two bridging μ-cyanoiron metalloligands to stabilize the {Fe(NO)2}10 unit. The lability of the FeII–CN–{Fe(NO)2}9/10 bond was probed by suitable X-type (Na+SPh) and L-type (PMe3) ligands. Treatment of Fe-1 and Fe*-1 with PMe3 accounted for a reduction-induced substitution at the DNIU, releasing [(η5-C5R5)Fe(dppe)(CN)] and N-heterocyclic carbene, and generating (PMe3)2Fe(NO)2 as the reduced {Fe(NO)2}10 product.

Graphical abstract: Bridging cyanides from cyanoiron metalloligands to redox-active dinitrosyl iron units

Supplementary files

Article information

Article type
Paper
Submitted
02 Maijs 2018
Accepted
05 Jūn. 2018
First published
06 Jūn. 2018

Dalton Trans., 2018,47, 11812-11819

Author version available

Bridging cyanides from cyanoiron metalloligands to redox-active dinitrosyl iron units

P. Ghosh, M. Quiroz, R. Pulukkody, N. Bhuvanesh and M. Y. Darensbourg, Dalton Trans., 2018, 47, 11812 DOI: 10.1039/C8DT01761A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements