Synthesis and Structural Chemistry of Non-Cyclopentadienyl Organolanthanide Complexes

Abstract

Over the years one major challenge has remained in organolanthanide chemistry: the synthesis of homoleptic alkyl and aryl complexes. The simplest organometallic compounds of the rare earths are the species LnR 2 or LnR 3 with the rare earth metals in their common oxidation states Ln 2+ and Ln 3+ which imply the coordination of only two or three ligands to the metal center. This is usually insufficient to meet the lanthanides' demands of steric saturation through high coordination numbers.Hence for a long time, only indirect evidence could be found for the existence of simple homoleptic organolanthanide compounds; the isolation and characterization of compounds belonging to this class were first achieved recently using pentafluorophenyl for Ln 2+ derivatives 12 and very bulky alkyl ligands for Ln 3+ species. [13][14][15] Especially for alkyls, very little structural data are available for compounds without any trimethylsilyl-substituted ligands which generally ensure higher stability. But nevertheless, due to the difficulties of their synthesis and their high reactivity alkyls and aryls still represent an interesting class of compounds. 16 Homoleptic σ-Alkyl ComplexesShortly after the synthesis of the first divalent solvent-free Ln alkyl, [(Me 3 Si) 3 C] 2 Yb, 17 the Eu analogue was prepared similarly by the reaction of EuI 2 and KC(SiMe 3 ) 3 in benzene. 18 It also features the bent structure displayed by the Yb complex but with a slightly smaller C-Eu-C angle (C-Eu-C ) 136°, C-Yb-C ) 137°) and longer Eu-C bonds (Eu-C ) 261 pm, Yb-C ) 249/250 pm). Salt metathesis was then again applied successfully to synthesize the first divalent Sm alkyl, Sm[C(SiMe 3 ) 2 (SiMe 2 OMe)] 2 (THF) Frank T. Edelmann was born in Hamburg, Germany, in 1954. He studied chemistry from 1974 to 1979 at the University of Hamburg, where he obtained his Diplom in 1979 and doctoral degree in 1983. His Ph.D. thesis entitled "The chemistry of the tricarbonyl(fulvene) chromium complexes" was carried out under the supervision of Prof. Ulrich Behrens. This was followed by two years (1983−1985) of postdoctoral research as a Feodor Lynen Fellow of the Alexander-von-Humboldt Foundation in the groups of Professors Josef Takats (

Bis(phosphinimino)methanide Borohydride Complexes of the Rare‐Earth Elements as Initiators for the Ring‐Opening Polymerization of ε‐Caprolactone: Combined Experimental and Computational Investigations

“…This distance is longer than observed for normal LaÀC bonds. [81] Compounds 2 and 3 are isostructural. Both compounds crystallize in the monoclinic space group P2 1 /n with four molecules of each complex in the unit cell ( Figure 2).…”

Near-IR Two Photon Microscopy Imaging of Silica Nanoparticles Functionalized with Isolated Sensitized Yb(III) Centers

“…[48][49][50][51][52] HOSi (OtBu) 3 is a useful model of an isolated silanol since the silicon is surrounded by four oxygen atoms, as in silica, three of which are -OtBu groups and one is the -OH reactive site. 53 Additionally, HOSi(OtBu) 3 can also accommodate secondary interactions between the metal center and the oxygen of the OtBu groups.…”

Rare Earth Arene-Bridged Complexes Obtained by Reduction of Organometallic Precursors

“…Because Cp is a 5-carbon, 6-electron aromatic system, it can readily diffuse the negative charge through resonance. Therefore, cyclopentadienyls bind 7 in the review, but the list is not meant to be exhaustive since several reviews cover the area of noncyclopentadienyl rare earth chemistry (Arnold and Casely, 2009;Diaconescu, 2008;Edelmann et al, 2002;Edelmann, 2009;Konkol and Okuda, 2008;Li et al, 2010;Piers and Emslie, 2002;Reznichenko and Hultzsch, 2010;Trifonov, 2010;Zeimentz et al, 2006). Fryzuk and co-workers pioneered the use of multidentate amidophosphine ligands, which combine soft phosphine and hard amide donors, and incorporated such motifs into the coordination sphere of group 3 metals, including the tridentate [N(SiMe2CH2P i Pr2)2] -(P2N) in (P2N)ScR2 (R = Me, Et, CH2SiMe3) (Fryzuk et al, 1996), tetradentate (PhP[CH2(SiMe2)N(SiMe2)CH2]2PPh) 2-(P2N2) in (P2N2)Y[CH(SiMe3)2] (Fryzuk et al, 1997), and, recently, the tetradentate fc(NP i Pr2)2 in [(fc(NP i Pr2)2)Sc(THF)(-H)]2 (Halcovitch and Fryzuk, 2013).…”