Synthesis and reactivity of [(DMSC)Ti(η2-OCAr2)L2] complexes (DMSC = dimethylsilyl-bridged p-tert-butylcalix[4]arene dianion, Ar = Aryl group, and L2 = delocalized diimine)

Jesudoss V. KIngston, Vallipuram Sarveswaran, Sean Parkin, Folami T. Ladipo

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Reactions of titanapinacolate complexes [(DMSC)Ti(OCAr2CAr2O)] (1, Ar = Ph; 2, Ar = p-MeC6H4; DMSC = 1,2-alternate dimethylsilyl-bridged p-tert-butylcalix[4]arene dianion) with 1 equiv of a delocalized diimine furnished titanium η2-ketone complexes [(DMSC)Ti(η2-OCAr2)L2] 3-6 (L2 = bpy, dmbpy, or phen). The ketone is weakly bound in 3-6, and it is readily dissociated. The compounds dissolve in aromatic hydrocarbon solvents to give intense green solutions and undergo a photochemically assisted transformation into 1-aza-5-oxa-titanacyclopentene derivatives 8-11, in which C-H activation of the heterocyclic diimine ligand and hydride migration to a Ti-bound ketone to form an alkoxide group has occurred. The reaction of 3-6 with one or more equivalents of appropriate ketone gave 8-11 in high yield. The compounds were characterized by NMR (1H and 13C) and microanalysis data, as well as by X-ray crystallography for [(DMSC)Ti{k3-OC(p-MeC6H4)2 C10H7N2}{OCH(p-MeC6 H4)2}] (9). The ease of transformation of [(DMSC)Ti{η2-OC(p-MeC6H4)2} L2] complexes (4, L2 = bpy; 5, L2 = dmbpy; 6, L2 = phen) into 9-11 tracks the facility of metal to diimine ligand charge transfer (MLCT) transition and increased in the order 5 < 4 ≪ 6. This transformation is suggested to occur by a mechanism that involves reversible coordination of ketone to titanium and a rate-limiting step that is dependent on ketone concentration.

Original languageEnglish
Pages (from-to)136-144
Number of pages9
JournalOrganometallics
Volume22
Issue number1
DOIs
StatePublished - Jan 6 2003

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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