This website uses cookies to give you the best user experience. If you continue
without changing your settings we'll assume you are happy to receive all RSC cookies.
You can change your cookie settings by navigating to our Privacy and Cookies page and following the instructions. These instructions
are also obtainable from the privacy link at the bottom of any RSC page.
Rare earth metal bis(silylamide) complexes bearing pyridyl-functionalized indenyl ligand: Synthesis, structure and performance in the living polymerization of L-lactide and rac-lactide
Organometallic Chemistry Laboratory, Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, P. R. China
E-mail: lyj@nit.zju.edu.cn
; Fax: +86-574-88130130
; Tel: +86-574-88130085
Dalton Trans., 2013,42, 1862-1871
DOI:
10.1039/C2DT32083E
Received
10 Sep 2012,
Accepted
06 Nov 2012
First published online
12 Nov 2012
Amine elimination of rare earth tris(silylamide) complexes Ln[N(SiHMe2)2]3(THF)2 (Ln = La, Sm, Er, Lu) with 1 equiv. of the pyridyl-functionalized indenyl ligand C9H7CMe2CH2C5H4N-α afforded a series of neutral mono-indenyl-ligated rare earth metal bis(silylamide) complexes (C9H6CMe2CH2C5H4N-α)Ln[N(SiHMe2)2]2 (Ln = La (1), Sm (2), Er (3), Lu (4)) in 83–87% isolated yields. Reaction of La[N(SiHMe2)2]3(THF)2 with 2 equivalents of C9H7CMe2CH2C5H4N-α provided the neutral bis(indenyl) lanthanum mono(silylamide) complex (C9H6CMe2CH2C5H4N-α)2LaN(SiHMe2)2 (5). These complexes were characterized by elemental analysis, FT-IR and NMR (except for 3 for the strong paramagnetic property of the central metal). X-ray single crystal structural diffraction showed that 1–4 are isostructural and the central metals are four-coordinated by one indenyl ring, one nitrogen atom from the pendant pyridyl group, and two amide groups to form a distorted tetrahedral geometry; while the central metal in 5 is five-coordinated by two indenyl rings, two nitrogen atoms from the pendant pyridyl groups, and one amide group to adopt a distorted pyramidal geometry, if the indenyl ring is regarded as occupying an independent vertex. The monoanionic pyridyl-functionalized indenyl ligand is bonded to the central metal in η5/κ1 constrained geometry configuration (CGC) mode. 1–4 are highly active for the ring-opening polymerization of L-lactide and rac-lactide. In the presence of 2 equivalents of benzyl alcohol, 1 shows high activity toward L-lactide and rac-lactide in a living fashion.
Fetching data from CrossRef. This may take some time to load.