Matthew A. Johnston

Heteroleptic and heterometallic divalent lanthanide bis(trimethylsilyl)amide complexes: mixed ligand, inverse sandwich, and alkali metal derivatives

Abstract The utility of the [(Me3Si)2N]− ligand in providing access to new members of three classes of divalent lanthanide organometallic complexes is demonstrated by the synthesis of inverse sandwich bimetallic, heteroleptic monometallic, and heterometallic bridged derivatives. {[(Me3Si)2N]Sm(THF)2}2(μ-C8H8) (1) can be obtained from [(Me3Si)2N]2Sm(THF)2, SmI2(THF)2, and K2C8H8 in THF and crystallizes from THF with a planar (C8H8)2− ring sandwiched between two {[(Me3Si)2N]Sm(THF)2}+ cations. The analogous {[(Me3Si)2N]Yb(THF)2}2(μ-C8H8) (2) can be generated from K[N(SiMe3)2], YbI2(THF)2, and K2C8H8 in THF. Heteroleptic (C5Me5)Yb[N(SiMe3)2](THF)2 (3) is generated from K[N(SiMe3)2] and [(C5Me5)Yb(THF)2(μ-I)]2 in THF and crystallizes from toluene with a distorted piano stool geometry. The bridged alkali metal derivatives {K2[Zr2(OiPr)9]} {Yb[N(SiMe3)2]3}(THF)3 (4), KSm[N(SiMe3)2]3 (5), and NaSm[N(SiMe3)2]3 (6) show the diversity of bridging modes available with [(Me3Si)2N]− ligands in complexes with similar Ln/N(SiMe3)2 sub-structures, in this case the trigonal planar {[(Me3Si)2N]3Ln}− anions.

Divalent lanthanide complexes free of coordinating anions: facile synthesis of fully solvated dicationic [LnLx]2+ compounds

Abstract Fully-solvated, divalent lanthanide dication complexes free of coordinating anions, [LnLx]2+, in which L=MeCN, THF, have been synthesized by protonation of amide, indenyl, and pentamethylcyclopentadienyl precursors. The Sm(II) dication [Sm(THF)7]2+ was initially isolated as [Sm(THF)7][BPh4]2, (1), by protonolysis of the indenyl complex (C9H7)2Sm(THF)3 with [Et3NH][BPh4]. Compound 1 can also be obtained from (C5Me5)Sm[N(SiMe3)2](THF)2 and [Et3NH][BPh4]. The Yb analog, [Yb(THF)6][BPh4]2, (2), was obtained from the reaction of the bimetallic [(C5Me5)Yb(THF)]2(C8H8) with AgBPh4 and the reaction of (C5Me5)Yb[N(SiMe3)2](THF)2 with [Et3NH][BPh4], but [YbLx]2+ is best obtained from the reaction of Yb[N(SiMe3)2]2(THF)2 with [Et3NH][BPh4]. Reaction of Yb[N(SiMe3)2]2(THF)2 with [Et3NH][BPh4] in THF followed by recrystallization from acetonitrile affords [Yb(MeCN)8][BPh4]2, (3). The seven THF molecules in 1 form a pentagonal bipyramidal ligand environment around Sm2+. Complex 2 has an octahedral Yb2+ coordination environment and 3 has a distorted square antiprismatic arrangement of MeCN ligands around Yb2+.

Structural studies of mono(pentamethylcyclopentadienyl)lanthanide complexes

The mono(pentamethylcyclopentadienyl) lanthanide complexes [(C5Me5)Yb(μ-I)(μ-η 5 : η 5-C5Me5)Yb(C5Me5)]n (1), {[(C5Me5)Sm]3(μ-Cl)4(μ 3-Cl)(μ 3-OH)(THF)}2 (2), {[(C5Me5)Sm]2 (μ-OH)(μ-Cl)4(μ 3-Cl)Mg(THF)2}2 (3), [(C5Me5)2Sm](μ-Cl)6(μ 3-Cl)2(μ 4-Cl)[(C5Me5)Sm]4 (4), {[(C5Me5)Nd]3(μ 3-Cl)4(μ 4-Cl)2(μ 3-O2CPh)2K2(η 6-C7H8)}2 (5), [(C5Me5)Nd(C8H8)]2(μ-dioxane) (6), [(C5Me5)Yb(MeOtBu)]2(μ-η 8 : η 8-C8H8) (7), [(C5Me5)Dy(μ-I)2]3 (8), and [(C5Me5) Tm(MeCN)6]I2 (9), have been identified by X-ray crystallography. 1 is unusual in that it has a μ-η 5 : η 5-C5Me5 ring that generates a local bent metallocene environment around ytterbium. Complexes 2–5 demonstrate the versatility of bridging chlorides in generating a variety of structures for mono(pentamethylcyclopentadienyl) lanthanide halides. Complex 6 shows how dioxane can generate a crystallographically-analyzable complex by bridging two mixed-ligand metallocene units that do not readily crystallize with THF. The structure of 7 shows how methyl tert-butyl ether (MTBE) ligates a lanthanide. Complex 8 is a trimeric cyclopentadienyl lanthanide halide unusual in that it has six bridging halides that roughly define a trigonal prism. Complex 9 constitutes an organometallic example of a lanthanide in which acetonitrile completely displaces iodide counterions.

Reactivity of the Europium Hexafluoroacetylacetonate (hfac) Complex, Eu(hfac)3(diglyme), and Related Analogs with Potassium: Formation of the Fluoride hfac "ate" Complexes [LnF(hfac)3K(diglyme)]2

The europium hexafluoroacetylacetonate complex Eu(hfac)3(diglyme) was synthesized to examine its fluorescence and conversion to a Eu(II) analog. Reaction of Eu(hfac)3(diglyme) with potassium produced the unexpected trivalent product [EuF(hfac)3K(diglyme)]2. This reduction system was studied further by synthesizing other Ln(hfac)3(diglyme) analogs and examining their reactivity with potassium. The Nd, Sm, and Gd analogs of Ln(hfac)3(diglyme) also react with potassium to form [LnF(hfac)3K(diglyme)]2 as observed for europium. Reactions of the Eu(II) precursors, EuI2(thf)4 and {[Zr2(OiPr)9]Eu(μ-I)}2 with K(hfac) also form trivalent products, namely Eu(hfac)3(diglyme) and [Zr2(OiPr)9]Eu(hfac)2.

Synthesis, Structure, and Reactivity of Organometallic Lanthanide–Dizirconium Nonaisopropoxide Complexes

Enhanced solubility of the dizirconiumnonaisopropoxide (dzni) complexes [(dzni)Ln(C5H5)] and [{(dzni)Ln}2(C8H8)] (shown here for Ln=Sm; R=iPr), compared with their cyclopentadienyl analogues, was revealed by examining the reactions of [{(dzni)LnI}2] with NaC5H5 and K2C8H8 to probe the compatibility of the dzni ligand with organometallic reagents.

Facile formation of luminescent terbium(III) aryloxide complexes directly from terbium metal including the X-ray crystal structures of Tb(OC6H3Me2-2,6)3(THF)3 and Tb(OC6H3iPr2-2,6)3(THF)2☆

Abstract Direct reaction of terbium metal in refluxing isopropanol and phenols provides the luminescent terbium aryloxide species Tb(OC6H3Me2-2,6)3(THF)3 (1) and Tb(OC6H3iPr2-2,6)3(THF)2 (2) in good yield. Crystallographic studies showed 1 to be fac-octahedral and 2 to be trigonal bipyramidal with the THF molecules in the axial positions.