Lanthanocene (Ln = PrIII, YbIII) chlorides involving tetramethyldisiloxane-interlinked cyclopentadienyl ligands

✍ Scribed by Jens Gräper; R.Dieter Fischer; Gino Paolucci

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 875 KB
• Volume: 471
• Category: Article
• ISSN: 0022-328X
• DOI: 10.1016/0022-328x(94)88111-1

✦ Synopsis

Two new lanthanocenophanes [{O(Me,SiCSH4)2}Pr'11C1. THF], (2; x = 1 or 2) and [(O(Me,SiC,H,)z)Yb'l'CI],

(3), were made from LnCI, (Ln = Pr or Yb) and K, [OfMe,SiCsHJ,] in THF. The 'H NMR spectra of THF-d, solutions of paramagnetic 2 (at + 35 to -25°C) and 3 fat < 10°C) reflect an asymmetrical disposition of the siloxy linkage, while solutions of 2 in CD&I, (at 20°C) and 3 in THF-ds (at > 100, respectively, display somewhat less complex 'H NMR spectra consistent with a virtually symmetrical position of the Me,SiOSiMe, unit with respect to the cent-Ln-cent' plane (cent = C,H,Si centroid). A low-temperature (-BW'C) single-crystal X-ray study of 3 has confirmed the presence of centrosymmetric, Cl-bridged dimers in which the molecular configuration of the mononuclear {O(Me,SiCsH,),)Yb"'CI, units correspond to that of the previously described complex [(O(Me,SiCsH,),Ti'"CI,]

(1). The high-resolution mass spectrum of 3 displays several signals from dinuclear fragments, the B/E-linked scans of which suggest, inter alia, intramolecular reorientation of at least one OfMe,SiC,H,), ligand from the chelating into a metal-bridging position.