Issue 24, 2003
From the journal:

Dalton Transactions

Low valent chromium complexes bearing N,O-chelating pyridyl-enolate ligands [OC(But)([double bond, length as m-dash]2-CHN5H3Me-x)]− (x = 3–6)

Vernon C. Gibson,a   Claire Newton,a   Carl Redshaw,*b   Gregory A. Solan,*c   Andrew J. P. Whitea  and  David J. Williamsa  

* Corresponding authors

a Department of Chemistry, Imperial College, London, South Kensington, UK

b Wolfson Materials and Catalysis Centre, School of Chemical Sciences and Pharmacy, University of East Anglia, UK

c Department of Chemistry, University of Leicester, University Road, Leicester, UK

Abstract

Treatment of [CrCl2(THF)] (THF = tetrahydrofuran) with the sodium salt of HOC(But)(2-CH2NC5H3Me-x)2 (x = 6) in refluxing THF results in fragmentation of the L2X (L = neutral donor, X = anionic donor) ligand to afford the square planar bis(pyridyl-enolate) chromium(II) complex [Cr{OC(But)([double bond, length as m-dash]2-CHNC5H3Me-6)}2] (1) and the by-product trans-[CrCl2(2,6-dimethylpyridine)2] (2). On prolonged heating in refluxing toluene, oxidation of 1 occurs yielding the octahedral tris(pyridyl-enolate) chromium(III) complex [Cr{OC(But)([double bond, length as m-dash]2-CHNC5H3Me-6)}3] (3). Similar use of the sodium salts of HOC(But)(2-CH2NC5H3Me-x)2 (x = 3–5) also results in ligand fragmentation but gives solely the chromium(III) tris-chelated complexes [Cr{OC(But)([double bond, length as m-dash]2-CHNC5H3Me-x)}3] [x = 3 (4), 4 (5), 5 (6)]. Surprisingly, prolonged heating in a sealed tube of a mixture of [CrCl2(THF)] and the sodium salt of HOC(But)(2-CH2NC5H3Me-x)2 (x = 6) in the presence of diphenylacetylene furnishes the bimetallic chromium(II) complex [ClCr{(μ-OC(But)(2-CH2NC5H3Me-6)2}CrCl] (7), in which the two intact L2X ligands bridge the Cr–Cr vector (2.92 Å), one acting as a bidentate ligand and the other as a tridentate ligand. Single crystal X-ray diffraction studies have been performed on 1, 2, 3, 6 and 7.

Graphical abstract: Low valent chromium complexes bearing N,O-chelating pyridyl-enolate ligands [OC(But)( [[double bond, length as m-dash]] 2-CHN5H3Me-x)]− (x = 3–6)

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Article information

DOI
https://doi.org/10.1039/B308881M
Article type
Paper
Submitted
28 Jul 2003
Accepted
02 Oct 2003
First published
16 Oct 2003

Dalton Trans., 2003, 4612-4617

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Low valent chromium complexes bearing N,O-chelating pyridyl-enolate ligands [OC(But)([double bond, length as m-dash]2-CHN5H3Me-x)]− (x = 3–6)

V. C. Gibson, C. Newton, C. Redshaw, G. A. Solan, A. J. P. White and D. J. Williams, Dalton Trans., 2003, 4612 DOI: 10.1039/B308881M

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