Organometallic Compounds of the Lanthanides. 180 (C₅Me₄CH₂CH₂CH=CH₂)₂Yb – an Olefin Complex of Ytterbium(II)?

Abstract

YbI2(THF)2 reacts with two equivalents of K[C5Me4CH2CH2CH=CH2] yielding unsolvated (C5Me4CH2CH2CH=CH2)2Yb (1). The molecular structure shows both tethered olefins orientated toward the Yb center.

Trivalent lanthanide–alkene complexes: Crystallographic and NMR evidence for coordination of tethered alkenes in the solid state and solution

“…When the metal ionic radii are corrected to that of sixcoordinate Y 3þ according to Shannon [35], the divalent complexes I and II, and the trivalent cationic complex Id, predict LneC term distances in the range 2.73e2.82 Å [22,23]. In fact, the corrected distances in the aryloxide tethered alkene complexes discussed here range from 2.94 to 3.14 Å, more than 0.2 Å longer.…”

“…The majority of these involve divalent lanthanide complexes containing Cp ligands with pendant alkene groups (I and II) [22,23], although there is one example of an alkyl complex with a coordinated tethered alkene (IV, Chart 1) [25]. A series of alkaline earth alkene complexes (III) that are closely related to the divalent lanthanide derivatives II have also been reported (Chart 1) [24].…”

“…This was the first lanthanideealkene structure reported and remains the only structurally characterized example without alkene tethering. Evans et al [22] and Schumann et al [23,24] reported the structures of several alkene-tethered cyclopentadienyl complexes of divalent lanthanides (I, II, Chart 1) and the closely related alkaline earths (III, Chart 1) that show alkene coordination. In fact, other than the interesting alkylealkene complex [Yb{h 1 :h 2 -C(SiMe 3 ) 2 SiMe 2 CH¼CH 2 }{OEt 2 }] 2 (m-I) 2 , (IV), these represented the extent of structurally characterized lanthanideealkene complexes prior to this work [25].…”

Alkenes and Allyl Complexes of the Group 3 Metals and Lanthanides

“…1, left) was reported by the group of Smith and coworkers. 36 Some years later, Evans 37 and Schumann 38,39 and coworkers detailed the structures of several alkene-tethered cyclopentadienyl complexes of divalent lanthanides (4Yb, 5Sm, 5Eu, 5Yb, Fig. 1, middle and right) and the closely related alkaline earths that display alkene coordination.…”