title: Four-membered heterometallacyclic d⁰ and d¹ complexes of Group 4 metallocenes with amidato ligands.
abstract: A study of the coordination chemistry of different amidato ligands [(R)N-C(Ph)O] (R=Ph, 2,6-diisopropylphenyl (Dipp)) at Group 4 metallocenes is presented. The heterometallacyclic complexes [Cp2M(Cl){κ(2)-N,O-(R)N-C(Ph)O}] M=Zr, R=Dipp (1 a), Ph (1 b); M=Hf, R=Ph (2)) were synthesized by reaction of [Cp2MCl2] with the corresponding deprotonated amides. Complex 1 a was also prepared by direct deprotonation of the amide with Schwartz reagent [Cp2Zr(H)Cl]. Salt metathesis reaction of [Cp2Zr(H)Cl] with deprotonated amide [(Dipp)N-C(Ph)O] gave the zirconocene hydrido complex [Cp2M(H){κ(2)-N,O-(Dipp)N-C(Ph)O}] (3). Reaction of 1 a with Mg did not result in the desired Zr(III) complex but in formation of Mg complex [(py)3Mg(Cl) {κ(2)-N,O-(Dipp)N-C(Ph)O}] (4; py=pyridine). The paramagnetic complexes [Cp'2Ti{κ(2)-N,O-(R)N-C(Ph)O}] (Cp'=Cp, R=Ph (7 a); Cp'=Cp, R=Dipp (7 b); Cp'=Cp*, R=Ph (8)) were prepared by the reaction of the known titanocene alkyne complexes [Cp2'Ti(η(2)-Me3SiC2SiMe3)] (Cp'=Cp (5), Cp'=Cp* (6)) with the corresponding amides. Complexes 1 a, 2, 3, 4, 7 a, 7 b, and 8 were characterized by X-ray crystallography. The structure and bonding of complexes 7 a and 8 were also characterized by EPR spectroscopy.
authors.affiliation: Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein-Strasse 29a, 18059 Rostock (Germany), Fax: (+49) 381-1281-51176.
authors.forename: Martin
authors.initials: M
authors.lastname: Haehnel
authors.forename: Jacqueline B
authors.initials: JB
authors.lastname: Priebe
authors.forename: Jacky C-H
authors.initials: JC
authors.lastname: Yim
authors.forename: Anke
authors.initials: A
authors.lastname: Spannenberg
authors.forename: Angelika
authors.initials: A
authors.lastname: Brückner
authors.forename: Laurel L
authors.initials: LL
authors.lastname: Schafer
authors.forename: Uwe
authors.initials: U
authors.lastname: Rosenthal
keywords: EPR spectroscopy; amidates; hafnium; metallacycles; titanium; zirconium