title: Synthesis and characterization of the titanium bisamide Ti{N(H)Ar(iPr6)}2 (Ar(iPr6) = C6H3-2,6-(C6H2-2,4,6-(i)Pr3)2 and its TiCl{N(H)Ar(iPr6)}2 precursor: Ti(II) → Ti(IV) cyclization.
abstract: The titanium bisamido complex Ti{N(H)Ar(iPr6)}2 (Ar(iPr6) = C6H3-2,6-(C6H2-2,4,6-(i)Pr3)2 (2), along with its three-coordinate titanium(III) precursor, TiCl{N(H)Ar(iPr6)}2 (1), have been synthesized and characterized. Compound 1 was obtained via the stoichiometric reaction of LiN(H)Ar(iPr6) with the Ti(III) complex TiCl3·2NMe3 in trimethylamine. Reduction of 1 with 1 equiv of KC8 afforded Ti{N(H)Ar(iPr6)}2 (2) in moderate yield. Both 1 and 2 were characterized by X-ray crystallography, NMR, and IR spectroscopy, magnetic studies, and by density functional theory (DFT) computations. The precursor 1 has quasi-four-coordinate coordination at the titanium atom, with bonding to two amido nitrogens and a chlorine as well as a secondary interaction to a flanking aryl ring of a terphenyl substituent. Compound 2 displays a very distorted four-coordinate metal environment in which the titanium atom is bound to two amido nitrogens and to two carbons from a terphenyl aryl ring. This structure is in sharp contrast to the expected two-coordinate linear structure that was observed in its first row metal (V-Ni) analogues. Magnetic studies confirm a d(1) electron configuration for 1 but indicate that Ti{N(H)Ar(iPr6)}2 (2) is diamagnetic at ambient temperature consistent with the oxidation of titanium to Ti(IV). The different structure of 2 is attributed to the high reducing tendency of the Ti(II) in comparison to the other metals.
authors.affiliation: Department of Chemistry, University of California , Davis, California 95616, United States.
authors.forename: Jessica N
authors.initials: JN
authors.lastname: Boynton
authors.forename: Jing-Dong
authors.initials: JD
authors.lastname: Guo
authors.forename: Fernande
authors.initials: F
authors.lastname: Grandjean
authors.forename: James C
authors.initials: JC
authors.lastname: Fettinger
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nagase
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Long
authors.forename: Philip P
authors.initials: PP
authors.lastname: Power