Ortho-linked polyaryloxide ligands and their titanium complexes

Document Type

Article

Abstract

Ortho-linked polyphenols, quaterphenol L(OH)4, and moderately hindered terphenol (Ph)L(OH)3 are developed as new multidentate polyaryloxide ligands for transition-metal chemistry. The polyphenols are synthesized using ortho-metalation and metal-catalyzed cross-coupling methodologies; the synthetic routes allow for facile electronic and steric modification of the basic ligand design. The Ti(IV) coordination chemistry of these ligands reveals a diverse collection of bridged structures: dimeric [Ti(μ-(Ph)LO3)(O(i)Pr)]2 (P21/n, a = 12.2699(5) Å, b = 11.7957(5) Å, c = 21.238(1) Å, β = 94.551(1)°, Z = 2, T = 170(2) K), dimeric [Ti2(μ-(Ph)LO3)2(μ-CI)(CI)(THF)] (P(1), a = 11.212(1) Å, b = 14.165(1) Å, c = 22.447(2) Å, α = 90.440(4)°, β = 93.345(4)°, γ = 111.164(4)°, Z = 2, T = 170(2) K), and trimeric [Ti3(μ,μ'-LO4)μ-O(i)Pr)2(O(i)Pr)6] (P21/n, a = 11.1022(5) Å, b = 18.7015(9) Å, c = 24.409(1) Å, β = 95.369(2)°, Z = 4, T = 170(2) K). The reaction of TiCl3(THF)3 with [(Ph)LO3]3- results in oxidation of Ti(III) to Ti(IV) and formation of the oxo dimer [Ti((Ph)LO3)(THF)]2(μ-O) (P1, a = 10.8649(6) Å, b = 12.1882(7) Å, c = 14.3349(9) Å, α = 65.602(3)°, β = 84.390(3)°, γ = 86582(3)°, Z = 1, T = 200(2) K); the oxo group presumably originates from the THF solvent. The titanium centers in these environments are either 5- or 6-coordinate, with distorted square pyramidal/trigonal bipyramidal and distorted octahedral geometries, respectively; the polyphenoxide chelate ligands are capable of bridging multiple oxophilic titanium sites.

Publication Date

8-7-2000

Publication Title

Inorganic Chemistry

ISSN

00201669

Volume

39

Issue

16

First Page

3696

Last Page

3704

PubMed ID

11196835

Digital Object Identifier (DOI)

10.1021/ic000275f

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