Synthesis and Structures of Lithium and Potassium Complexes of Phosphanyl-Substituted Bis[1,3-bis(trimethylsilyl)cyclopentadienyl]yttriates

Abstract

The metathesis reaction of [(THF)4Li][Cp‘ ‘2Li] (1) (Cp‘ ‘ = 1,3-(Me3Si)2C5H3) with yttrium trichloride yields bis(tetrahydrofuran)lithium bis[1,3-bis(trimethylsilyl)cyclopentadienyl]dichloroyttriate (2). The metathesis reaction of 2 with potassium (triisopropylsilyl)phosphanide in toluene gives a stepwise exchange of the chloride ligands with the phosphanide substituents. In contrast to bis(tetrahydrofuran)lithium bis[1,3-bis(trimethylsilyl)cyclopentadienyl][(triisopropylsilyl)phosphanyl]chloroyttriate (3), which appears as an intermediate observable by NMR spectroscopy, (tetrahydrofuran)lithium bis[1,3-bis(trimethylsilyl)cyclopentadienyl][bis(triisopropylsilyl)phosphanyl]yttriate (4) is isolated as a colorless crystalline material with a YP2Li cycle and Y−P bond lengths of 2.840 Å. In solution a dissociation is observed into lithium (triisopropylsilyl)phosphanide and the THF complex of bis[1,3-bis(trimethylsilyl)cyclopentadienyl][(triisopropylsilyl)phosphanyl]yttrium (5). The reaction of either 2 or 4 with potassium (triisopropylsilyl)phosphanide in benzene yields (η6-benzene)potassium bis[1,3-bis(trimethylsilyl)cyclopentadienyl][bis(triisopropylsilyl)phosphanyl]yttriate (6) with a YP2K cycle and Y−P distances of 2.846 Å. The metathesis reaction of 2 with (DME)LiPH2 gives (1,2-dimethoxyethane)lithium bis[1,3-bis(trimethylsilyl)cyclopentadienyl]bis(phosphanyl)yttriate, which reacts with TMEDA to give colorless bis[(TMEDA)lithium] bis[1,3-bis(trimethylsilyl)cyclopentadienyl]bis(phosphanyl)yttriate chloride (7). The central YP2Li2Cl cycle is nearly planar with Y−P bond lengths of 2.849 Å.

Lanthanoid–Transition‐Metal Bonding in Bismetallocenes

“…For a better understanding of the implications of the covalent character of the polar LnTM bonding situation, a comparison between [Cp 2 ReYCp 2 ] ( 3 a ) with the hypothetical model system [Cp 2 LiYCp 2 ], both fully optimized in C 2 v symmetry, is presented below (Table 3). The fragment [Cp 2 Li] − was chosen as an example of a well‐documented metallocene anion30 that is unlikely to show any metal‐based electron donation. As can be expected, with an effective charge of +0.88, the alkali metal turns out to be slightly higher charged than the transition metal (+0.70).…”

Chloro, Alkyl and Aryl Complexes of Rare Earth Metals Supported by Bulky Tetrasubstituted Guanidinate Ligands

“…The Y–N(1,2) distances [2.352(1), 2.357(1) Å] differ only very slightly and are in the range of the corresponding distances for the related yttrium guanidinate and amidinate complexes {[(Me 3 Si) 2 NC(N i Pr) 2 ] 2 Y(μ‐Cl)} 2 [2.326(4)–2.388(4) Å],6b {[PhC(NSiMe 3 ) 2 ] 2 Y(μ‐H)} 2 [2.327(3)–2.389(3) Å]12a and [PhC(NSiMe 3 ) 2 ] 2 Y(μ‐Cl) 2 Li(TMEDA) [2.334(2)–2.373(2) Å] 13. The Y–Cl distances [2.669(1) Å] are slightly longer than those in the metallocene type “ate” complexes Cp* 2 Y(μ‐Cl) 2 Li(THF) 2 [2.646(2), 2.655(2) Å]14 and [(1,3‐Me 3 Si) 2 C 5 H 3 ] 2 Y(μ‐Cl) 2 Li(THF) 2 [2.626(1), 2.631(1) Å]15but shorter than the Y–Cl bonds in the dimericcomplex {[(Me 3 Si) 2 NC(N i Pr) 2 ] 2 Y(μ‐Cl)} 2 [2.7128(15), 2.7166(15) Å] 12b. The bite angle C(13)–Y(1)–C(13′) [125.77(5)°] is substantially smaller than that in 6 [130.3(2)°].…”

Synthesis, structure and reactivity of rare-earth metal complexes containing anionic phosphorus ligands

“…Three mixed ligated mode II cyclopentadienyl yttriate complexes [Cp 00 2 Y(m-Cl) 2 Li(THF) 2 ] with TMEDA and (DME)LiPH 2 (DME = 1,2-dimethoxyethane) is extremely sensitive toward moisture and air and decomposes at room temperature even under an argon atmosphere (Scheme 3). 16 In contrast to other ''ate'' complexes, Hou and coworkers showed an example of a divalent mono-phosphide bridged polymeric mode II complex. [Cp*Sm(THF)(m-PHAr)KCp*(THF)] N (10) was prepared by reacting [Cp* 2 Sm(THF) 2 ] with 1 equiv.…”