Coordination modes in zirconium β-diketiminate complexes

• Published in: Inorganic chemistry communications 2010-04, Vol.13 (4), p.529-533
• Main Authors: El-Zoghbi, Ibrahim, Verguet, Emilie, Oguadinma, Paul, Schaper, Frank
• Format: Article
• Language: English
• Subjects: Coordination mode; Diketiminate; Haptotropic shift; Nacnac; Zirconium
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/j.inoche.2010.01.029

Pseudo-tetrahedral zirconium diketiminate complexes display a bonding mode intermediate between in-plane, κ 2 and out-of-plane, “η 5-like”, which is best described as a non-symmetric κ 2,η 2-coordination. Reaction of β-diketiminate lithium salts, nacnac RLi(THF) (R = 2,6-xylyl ( 1a), R-CH(Me)Ph ( 1b)), with ZrCl 4 or ZrCl 4·THF yielded the mono-diketiminate complexes nacnac RZrCl 3(THF), 2a and 2b. Complex 2a did not react further with a second equivalent of 1a, but with CpLi or IndLi to form pseudo-tetrahedral complexes 3 and 4. No product could be isolated from reaction of 2b with CpLi. Coordination of the diketiminate ligand in 2a is best described as a distorted κ 2-, in-plane coordination. Complexes 3 and 4, however, display a haptotropic shift of the diketiminate ligand and its coordination is best described as κ 2,η 2-coordination. Although not previously described, analyses of available structures in the literature reveal that non-symmetric κ 2,η 2-coordination is an independent coordination mode, which exists next to the previously described “η 5-like” coordination.