Issue 46, 2010
From the journal:

Dalton Transactions

Formation of μ-dinitrogen (salen)osmium complexes via ligand-induced N⋯N coupling of (salen)osmium(vi) nitrides†

Wai-Lun Man,a   Gui Chen,a   Shek-Man Yiu,a   Lam Shek,a   Wai-Yeung Wong,b   Wing-Tak Wongc  and  Tai-Chu Lau*a  

* Corresponding authors

a Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, PRC
E-mail: bhtclau@cityu.edu.hk
Fax: (+852)27887406
Tel: (+852)27887811

b Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, PRC

c Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, PRC

Abstract

Treatment of [NnBu4][OsVI(N)Cl4] with a stoichiometric amount of H2L (L = N,N′-bis(salicylidene)-o-cyclohexylenediamine dianion) in the presence of PF6− or ClO4− in MeOH affords [OsVI(N)(L)(OH2)](PF6) 1a and [OsVI(N)(L)(CH3OH)](ClO4) 1b, respectively. The structure of 1b has been determined by X-ray crystallography and the Os[triple bond, length as m-dash]N bond distance is 1.627(3) Å. In the presence of a N-donor heterocyclic ligand in CH3CN, 1a reacts at room temperature to afford the mixed-valence μ-N2 (salen)osmium species [(X)(L)OsIII–N[triple bond, length as m-dash]N–OsII(L)(X)](PF6), 2–14 (X = py 2; 4-Mepy 3; 4-tBupy 4; pz 5; 3-Mepz 6; 3,5-Me2pz 7; Im 8; 1-MeIm 9; 2-MeIm 10; 4-MeIm 11; 1,2-Me2Im 12; 2-Meozl 13; 4-MeTz 14). These complexes are formed by ligand-induced N⋯N coupling of two [OsVI[triple bond, length as m-dash]N]+ to give initially [OsIII–N2–OsIII]2+, which is then reduced to give the more stable mixed-valence species [OsIII–N2–OsII]+. Cyclic voltammograms (CVs) of 2–14 show two reversible couples, attributed to OsIII,III/OsIII,II and OsIII,II/OsII,II. The large comproportionation constants (Kcom) of (5.36–82.3) × 1013 indicate charge delocalization in these complexes. The structures of 3 and 14 have been determined by X-ray crystallography, the salen ligands are in uncommon cis-β configuration. Oxidations of 4 and 14 by [Cp2Fe](PF6) afford the symmetrical species [(X)(L)OsIII–N[triple bond, length as m-dash]N–OsIII(L)(X)](PF6)2 (X = 4-tBupy 15; 4-MeTz 16). These are the first stable μ-N2 diosmium(III,III) complexes that have been characterized by X-ray crystallography.

Graphical abstract: Formation of μ-dinitrogen (salen)osmium complexes via ligand-induced N⋯N coupling of (salen)osmium(vi) nitrides

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Article information

DOI
https://doi.org/10.1039/C0DT00481B
Article type
Paper
Submitted
17 May 2010
Accepted
09 Sep 2010
First published
21 Oct 2010

Dalton Trans., 2010,39, 11163-11170

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Formation of μ-dinitrogen (salen)osmium complexes via ligand-induced N⋯N coupling of (salen)osmium(VI) nitrides

W. Man, G. Chen, S. Yiu, L. Shek, W. Wong, W. Wong and T. Lau, Dalton Trans., 2010, 39, 11163 DOI: 10.1039/C0DT00481B

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