o-(Cyclohexyliminoethyl)(arylamido)benzene and related complexes of zirconium and titanium. The non-innocence of the ketimino functionality

Abstract

N-Arylamido complexes of zirconium in which the amido functional group is attached to an o-(alkyliminoethyl) substituted aromatic ring, have been synthesised by salt elimination reactions and characterised by spectroscopic and diffraction methods; they are analogous to the N-silylamido species recently reported (Dalton Trans., 2002, 3290-3299). The ligands 2-[CyN=C(CH(3))]C(6)H(4)N(H)(xyl), L(xyl)H, and 2-[CyN=C(CH(3))]C(6)H(4)N(H)(mes) L(mes)H, Cy = C(6)H(11), xyl = 3,5-Me(2)C(6)H(3) mes = 2,4,6-Me(3)C(6)H(2), were prepared in good yields by Buchwald-Hartwig amination of the arylbromides with 2-[CyN=C(CH(3))]C(6)H(4)NH(2). Reaction of L(mes)Li with Zr(NEt(2))(2)Cl(2)(thf)(2) gave after chloride substitution the arylamido ketimino complex L(mes)Zr(NEt(2))(2)Cl 1; variable amounts of the arylamido vinylamido complex 2 were also obtained. Interaction of L(mes)Li or L(xyl)Li with Ti(NMe(2))(2)Cl(2) gave rise to the tripodal bis-amido amino complexes 5 and 6 possibly formed by ligand rearrangement involving migration of the dimethylamido group to the ketimino carbon.

Bis(diethylamido-κN)(diethylamine-κN)bis(2,6-diisopropylphenylamido-κN)zirconium(IV)

“…; Blake et al, 1997). In case of two NEt 2 ligands distances Zr-N differ by about 0.12 Å but both are in the range typical for zirconium complexes with diethylamido ligands (Porter et al, 2004;Ghesner et al, 2006). Comparing angles between N1-Zr1-N2, N2-Zr1-N5 and N5-Zr1-N1 [table 1] it can be seen that they are roughly 120°, in addition the angle between N3-Zr1-N4 [table 1] indicates that molecular geometry is close to trigonal bipyramidal.…”

“…For related zirconium(IV) structures, see: Profilet et al (1990); Blake et al (1997); Porter & Danopoulos (2004); Ghesner et al (2006). For related syntheses, see: Kempe (2000).…”

Synthesis, Characterization, and Reactivity of Low-Coordinate Titanium(III) Amido Complexes

“…Single crystals of 1 were grown from a concentrated 1:1 pentane/toluene solution, and the solid-state structure was determined by X-ray crystallography. The solid-state structure of 1 consists of molecular units possessing a planar central Ti 2 (μ-Cl) 2 core with terminal chloride ligands oriented in a transoid fashion (Figure ), a common motif for dinuclear titanium­(III) species bridged by two chloride ligands. − Notably, Yélamos and co-workers isolated and characterized the analogous pentamethylcyclopentadienyltitanium­(III) complex [{Ti­(η 5 -C 5 Me 5 )­Cl­(μ-Cl)} 2 ], which exhibits similar structural parameters, and this indicates that the [N­(Si i Pr 3 )­DIPP] and η 5 -C 5 Me 5 ligands have comparable steric profiles …”

Coordination modes in zirconium β-diketiminate complexes

“…The N1, N2, C1, C2 fragment remains essentially planar with twist angles below 10°. The latter group (3,4,(9)(10)(11)(12) shows a distorted ligand mean plane with twist angles above 15°, significant differences in Zr-C2/4 distances (>0.2 Å), in Zr-C2/4-C1/5 angles (>25°) and increased C-N-C2/ 4-C1/5 torsion angles (>15°).…”

“…In mono-[2-9] and bis(diketiminate) complexes of zirconium [4,6,7,10], as well as in complexes with the related iminomethylaniline [11,12] or azaallylpyridine ligands [13,14], the ligand is bound via the two nitrogen lone pairs with the metal found in the ligand mean plane (Scheme 1, A). Steric crowding around the metal center, in particular with sterically demanding substituents on nitrogen, results in a displacement of the metal out of the ligand mean plane (Scheme 1, B) [1,3].…”