Neutral and cationic rare-earth metal alkyl complexes that contain bis(2-methoxyethyl)(trimethylsilyl)amine, a neutral [ONO]-type ligand Peter M. Zeimentz, Thomas P. Spaniol, Jun Okuda * Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany Received 13 March 2006; accepted 10 April 2006 Available online 22 April 2006 Dedicated to Professor Dr. Dr. h.c. mult. Wolfgang A. Herrmann. Abstract Neutral tris(trimethylsilylmethyl) complexes [Ln(CH 2 SiMe 3 ) 3 (L)] (Ln = Sc (1), Lu (2)) and cationic bis(trimethylsilylmethyl) complexes [Ln(CH 2 SiMe 3 ) 2 (L)(THF)] + [BPh 4 ] À , (Ln = Sc (3), Lu (4)) that contain bis(2-methoxyethyl)(trimethylsilyl)amine (L = Me 3 SiN(CH 2 - CH 2 OMe) 2 ) as a neutral, tridentate ligand were synthesized and characterized by NMR spectroscopy. X-ray structural analysis was performed for the scandium complex 1 and exhibited a distorted octahedral coordination geometry with a facially arranged ligand at the neutral scandium center. NMR spectroscopy corroborated the coordination of the tertiary amine function of the ligand to the metal. Complexes 3 and 4 expand the still limited range of cationic rare-earth metal alkyl complexes with known neutral, multidentate ligands. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Scandium; Lutetium; Rare-earth metals; Cations; Coordination chemistry 1. Introduction In contrast to the numerous neutral and anionic com- plexes, only recently have cationic rare-earth organometal- lic complexes been described [1]. The increased attention to these cationic complexes is caused by the growing interest in the development of more active catalysts for olefin poly- merization [2]. In particular, a number of post-metallocene alkyl complexes of the rare-earth metals have been described [3]. The majority of these complexes incorporate mono- and dianionic ligands. Examples of neutral, multi- dentate ligands for the coordination of cationic rare-earth metal alkyl complexes include 1,4,7-trimethyl-1,4,7-triaza- cyclononane [4], tris(3,5-dimethylpyrazolyl)methane [4b], 1,1,1-tri{2-[(S)-4-isopropyl]oxazolyl}ethane [5] and 1,4, 7-trithiacyclononane [6]. We have recently succeeded in utilizing crown ethers to isolate and structurally fully char- acterize an extensive series of rare earth metal alkyl cations [7]. Here we report the use of bis(2-methoxyethyl)(trimeth- ylsilyl)amine (L = Me 3 SiN(CH 2 CH 2 OMe) 2 ) as a neutral, chelating ligand to coordinate neutral and cationic scan- dium and lutetium alkyl complexes and their characteriza- tion by NMR spectroscopy and X-ray crystallography. 2. Experimental 2.1. General considerations All operations were performed under an inert atmosphere of argon using standard Schlenk-line or glovebox techni- ques. Anhydrous lanthanoid trichlorides (Aldrich or Strem) were used as received. [Ln(CH 2 SiMe 3 ) 2 (THF) 3 ] + [BPh 4 ] À complexes [7c] and bis(2-methoxyethyl)(trimethylsilyl)- amine [8] were synthesized according to the literature proce- dures. Solvents and all other chemicals were commercially available and used after appropriate purification. NMR spectra were recorded on a Varian Unity 500 spectrometer ( 1 H, 499.6 MHz; 13 C, 125.6 MHz; 11 B, 160.3 MHz) at 25 °C. Chemical shifts for 1 H and 13 C NMR spectra were 0020-1693/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2006.04.018 * Corresponding author. Tel.: +49 241 8094645; fax: +49 241 8092644. E-mail address: jun.okuda@ac.rwth-aachen.de (J. Okuda). www.elsevier.com/locate/ica Inorganica Chimica Acta 359 (2006) 4769–4773