Zirconium complexes of amino(polyphenolic) ligands and their hydrolytic stability

Chartres, Jy D.; Dahir, Ahmed; Tasker, Peter A.; White, Fraser

doi:10.1016/j.inoche.2007.06.004

Cited by 6 publications

(1 citation statement)

References 13 publications

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“…The free triphenol is revealed by X-ray crystallography (Tables −) to have, at least in the solid state, an approximately C 3 -symmetric conformation with the three phenols pointed inward toward the lone pair of the central nitrogen (Figure ). This conformation, which is preorganized for metal binding, has been observed with other tripodal triphenols with tert -butyl groups in the ortho position, while less bulky triphenols adopt a conformation with one of the OH groups turned away from the amine . A similar preorganized conformation has also been seen with other amine-centered tripodal ligands …”

Section: Resultssupporting

confidence: 72%

Redox-Active Tripodal Aminetris(aryloxide) Complexes of Titanium(IV)

et al. 2010

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New sterically encumbered tripodal aminetris(aryloxide) ligands N(CH(2)C(6)H(2)-3-(t)Bu-5-X-2-OH)(3) ((tBu,X)LH(3)) with relatively electron-rich phenols are prepared by Mannich condensation (X = OCH(3)) or by a reductive amination/Hartwig-Buchwald amination sequence on the benzyl-protected bromosalicylaldehyde (X = N[C(6)H(4)-p-OCH(3)](2)), followed by debenzylation using Pearlman's catalyst (Pd(OH)(2)/C). The analogous dianisylamino-substituted compound lacking the tert-butyl group ortho to the phenol ((H,An(2)N)LH(3)) is also readily prepared. The ligands are metalated by titanium(IV) tert-butoxide to form the five-coordinate alkoxides LTi(O(t)Bu). Treatment of the tert-butoxides with aqueous HCl yields the five-coordinate chlorides LTiCl, and with acetylacetone gives the six-coordinate diketonates LTi(acac). The diketonate complexes (tBu,X)LTi(acac) show reversible ligand-based oxidations with first oxidation potentials of +0.57, +0.33, and -0.09 V (vs ferrocene/ferrocenium) for X = (t)Bu, MeO, and An(2)N, respectively. Both dianisylamine-substituted complexes (R,An(2)N)LTi(acac) (R = (t)Bu, H) show similar electrochemistry, with three one-electron oxidations closely spaced at approximately 0 V and three oxidations due to removal of a second electron from each diarylaminoaryloxide arm at approximately + 0.75 V. The new electron-rich tripodal ligands therefore have the capacity to release multiple electrons at unusually low potentials for aryloxide groups.

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Section: Resultssupporting

confidence: 72%

Redox-Active Tripodal Aminetris(aryloxide) Complexes of Titanium(IV)

et al. 2010

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Redox Chemistry and Electrochemistry of Homoleptic Metal Phenolates

Biani

Corsini

Zanello

2014

Patai's Chemistry of Functional Groups

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The redox chemistry of aryl alcohols, or phenols, is of great interest because of their involvement in important biological and industrial processes. Phenol and its substituted analogs are facile one‐electron reducing agents that are often involved in electrochemical, photochemical and radiation chemical electron transfer reactions. For these and many other reasons the interest of chemists in the metal phenolates has always been lively and a huge number of these complexes are known. In this chapter we describe the redox behavior of the more restricted set of homoleptic aryloxide complexes. The peculiarities of phenolates as ligands make them usually unable to stabilize a metal in different redox states and, very often, reduction of the metal is accompanied by the release of one or more of the ligands and/or by the formation of polynuclear compounds. This may give rise to a complicated pattern in the redox chemistry of these complexes, but may also open the way to a rich, redox‐driven, chemistry of this class of compounds, which, apparently, is still largely unexplored.

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Coordination Chemistry and Applications of Nitrilotris(N‐Methylenephenoxy)–Metal Complexes

Míriam

Zonta

Licini

2014

Patai's Chemistry of Functional Groups

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Nitrilotris( N ‐methylenephenols), commonly called triphenolamines (TPA), are highly modular, tetradentate molecules that effectively coordinate to transition metals and main group elements with podand topology. They form chiral complexes with intrinsically well‐defined geometries (pentacoordinate trigonal bipyramidal, hexacoordinate octahedral, and, more rarely, trigonal monopyramidal geometries) controlled by the ligand. Nitrilotris( N ‐methylenephenoxy)–metal complexes have been found to be effective and robust catalysts in a series of important processes like polymerizations (titanium(IV), zirconium(VI), hafnium(VI), germanium(VI), and vanadium(V) complexes), oxygen transfer reactions (titanium(VI), vanadium(V), molybdenum(VI), and nickel(II) complexes), carbon–carbon bond formation (aluminium(III), and titanium(VI) complexes), carbon dioxide fixation (iron(III) complexes), and metathesis (Mo(VI) complexes).

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Zirconium complexes of amino(polyphenolic) ligands and their hydrolytic stability

Cited by 6 publications

References 13 publications

Redox-Active Tripodal Aminetris(aryloxide) Complexes of Titanium(IV)

Redox-Active Tripodal Aminetris(aryloxide) Complexes of Titanium(IV)

Redox Chemistry and Electrochemistry of Homoleptic Metal Phenolates

Coordination Chemistry and Applications of Nitrilotris(N‐Methylenephenoxy)–Metal Complexes

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