Di‐ and Trivalent Ytterbium Complexes Containing Linked Amino‐ and Amidocyclopentadienyl Ligands

Abstract

Reactions of the aminocyclopentadienes (C5Me4H)SiMe2NHR (R = Et, allyl, nPr, tBu) with [YbI2(THF)2] in the presence of two equivalents of potassium 1,2‐diphenylethenide in THF at room temperature gave the diamagnetic half‐sandwich complexes [Yb(η5‐C5Me4SiMe2NHR)Ln(μ‐I)]2 (L = THF, n = 2, L = DME, n = 1). The tert‐butylamido derivative [Yb(η5‐C5Me4SiMe2NHtBu)(THF)2(μ‐I)]2 was characterized by X‐ray structural analysis as a dinuclear complex containing a nonchelating aminocyclopentadienyl ligand. Deprotonation of the aminocyclopentadiene (C5H4tBu)SiMe2NHtBu with two equivalents of potassium 1,2‐diphenylethenide in THF, followed by reaction with [YbI2(THF)2] at 60 °C, gave the trivalent ytterbium ate complex [K(DME)][Yb{(η5:η1‐C5H3tBu‐3)SiMe2NtBu}2]. A single crystal X‐ray diffraction study of this complex shows polymeric chains consisting of trivalent ytterbocene units with two chelating amidocyclopentadienyl ligands coordinated to potassium ions. Metalation of the aminoindene (C9H7)SiMe2NHtBu under the same conditions and treatment with [YbI2(THF)2] in THF at ambient temperature resulted in the formation of the divalent ytterbocene complex [Yb{η5‐(1‐C9H6)SiMe2NHtBu}2(THF)2]. The reaction of ytterbium naphthalenide [Yb(C10H8)(THF)2] with one equivalent of (C9H7)SiMe2NHtBu afforded the bis(indenyl) compound which was isolated as its 2,2′‐bipyridyl adduct [Yb{η5‐(1‐C9H6)SiMe2NHtBu}2(bipy)]. It was shown by single‐crystal structural analysis to exhibit a bent metallocene structure with noncoordinating amino side‐chains. The reaction of (C5Me4H)CH2SiMe2NHtBu, which contains a longer CH2SiMe2 bridge, with [Yb(C10H8)(THF)2] gave the complex [Li0.5][Yb(μ‐η5:η1‐C5Me4CH2SiMe2NtBu)(THF)2(μ‐I)0.5]. Single crystal X‐ray structure analysis revealed the presence of polymeric chains consisting of dinuclear iodo‐bridged [Yb(η5:η1‐C5Me4CH2SiMe2NtBu)] units with a chelating linked amidocyclopentadienyl ligand, intermolecularly bridged by lithium ions. The lithium ions are bonded in an η5‐manner to both units, forming a lithocene structure. When YbCl3 was reacted with Li2[(C5H3tBu‐3)SiMe2NCH2CH2X] (X = NMe2, OMe), heterobimetallic complexes Li[Yb{(η5:η1‐C5H3tBu‐3)SiMe2NCH2CH2X}2] with a helical metallocene structure were isolated. The single crystal structure analysis of one of the three possible diastereomers of Li{Yb[(η5:η1‐C5H3tBu‐3)SiMe2NCH2CH2NMe2]2}, viz. the thermodynamically stable (R,R)/(S,S) epimer was performed. When YbCl3 was reacted with one equivalent of Li2[(C5H3tBu‐3)SiMe2NCH2CH2NMe2] and reduced “in situ” with one equivalent of sodium 1,2‐diphenylethenide in THF, the ytterbium(II) metallocene complex [Li(THF)]2[Yb{(η5‐C5H3tBu‐3)SiMe2NH(CH2CH2NMe2)}2(μ‐Cl)2] was isolated, which exhibits a structure with the two amino functions coordinating to the lithium ions and the chloro ligands bridging both the lithium and ytterbium centers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Di-μ-iodido-bis[(diethyl ether-κO)(η5-1,3-di-tert-butylcyclopentadienyl)ytterbium(II)]

“…The distances and angles fall within normal ranges for Yb(II) in 6coordination. (Schultz et al, 2000) The structure is similar to those of the published dimers {(Me 5 C 5 )Yb(THF) 2 -µ-I} 2 , {(Me 5 C 5 )Yb(dme)-µ-I} 2 , (Constantine et al, 1996) and {[Me 4 [SiMe 2 NH(CMe 3 )]C 5 ]Yb(THF) 2 -µ-I} 2 (Trifonov et al, 2003), in which the Yb(II) is 7-coordinate.…”

“…For related structures, see: Constantine et al (1996); Trifonov et al (2003). For related chemistry, see: Schultz et al (2000); Schumann et al (1993).…”

Reactions of ytterbium(II) bis(indenyl) complex (C9H7)2Yb(thf)2 with 2,2’-bipyridine and 1,4-bis(2,6-diisopropylphenyl)-1,4-diazabuta-1,3-diene. Structures and properties of (C9H7)2Yb(bipy) and (C9H7)2Yb(2,6-Pri 2C6H3NCHCHNC6H3Pri 2-2,6) complexes

“…15 The metal-nitrogen bonds in complex 2 (2.456(2), 2.433(2), 2.456(2), and 2.434(2) Å) are some what shorter than the corresponding distances in the ytterbium(II) pyridyl complex (C 5 Me 5 ) 2 Yb(py 2 ) (2.586(7) and 2.544(6) Å) 16 but are comparable to the analogous bonds in the related bipyridine com pound (C 9 H 6 SiMe 2 NHBu t ) 2 Yb(bipy) (2.454(3) and 2.476(4) Å). 17 The Cp c -Yb-Cp c angles in compound 2 (132.0 and 132.4°) are noticeably larger than that in the start ing complex 1 (128.6°) 14 but they are virtually equal to the angle found 17 in (C 9 H 6 SiMe 2 NHBu t ) 2 Yb(bipy) (132.1(3)°). Apparently, this is attributable to larger steric crowding of the coordination sphere of the metal Int.Ed., Vol.…”

Yb(II) Triple-Decker Complex with the μ-Bridging Naphthalene Dianion [CpBn5Yb(DME)]2(μ-η4:η4-C10H8). Oxidative Substitution of [C10H8]2– by 1,4-Diphenylbuta-1,3-diene and P4 and Protonolysis of the Yb–C10H8 Bond by PhPH2

“…The mean Yb–Cp center distance in 4 (2.41(2) Å) falls into the interval typical for Yb­(II) sandwich [(Me 3 Si) 2 C 5 H 3 ] 2 Yb­(THF) (2.39 Å) and half-sandwich [(C 5 Me 5 )­YbI­(THF) 2 ] 2 (2.41 Å) complexes. The Yb–Cp center and Yb–O (2.447(3) and 2.463(3) Å) bond distances are both indicative of the divalent state of ytterbium (for a comparison of Yb–Cp center and Yb–O bond lengths in Yb­(II) complexes see refs and ).…”