Michael A. Greci

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+.

Direct Synthesis of Heterometallic Europium/Barium Complexes: H2[Eu2Ba6O2(OiPr)16(THF)4] and EuBa2(OC6H4Me-4)7(diglyme)2(DME)

Convenient syntheses of mixed-metal Eu/Ba complexes starting from the elemental metals have been explored. A mixture of europium and barium ingots reacts in boiling 2-propanol to form a product which crystallizes from THF as the heterometallic complex formulated as H2[Eu2Ba6O2(OiPr)16(THF)4] (1). An analogous reaction in the presence of p-cresol (HOC6H4Me-4) forms trimetallic EuBa2(OC6H4Me4)7(diglyme)2(DME) (2), after recrystallization from THF/DME/diglyme (DME = 1,2-dimethoxyethane). Complex 1 exhibits an octametallic geometry comprised of two square pyramids with coplanar bases which share a basal edge and have apices on opposite sides. The six barium atoms occupy the basal positions and the two europium atoms are at the apices. Complex 2 exhibits a triangular arrangement of metal atoms with both terminal and bridging aryloxide ligands coordinated to the europium atom and bridging aryloxide and terminal ether ligands coordinated to the barium atoms.

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.

Synthesis and structure of a mixed valence metal carbitoxide complex: Eu3[O(CH2CH2O)2CH2CH3]4(OC6H3iPr2-2,6)3

Abstract The direct reaction of europium metal with HO(CH2CH2O)2CH2CH3 followed by treatment with 2,6-iPr2C6H3OH leads to the crystallographically-characterizable, mixed valent carbitoxide product Eu3[O(CH2CH2O)2CH2CH3]4(OC6H3iPr2-2,6)3 (1), which contains bridging alkoxide ligands and both terminal and bridging aryloxide ligands.

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.

ϵ‐Caprolactam as a Donor Ligand for Lanthanide Halides: Formation of Cationic [Ln(C6H11NO)6Cl]2+ and [Ln(C6H11NO)4Cl2]+ Complexes

Examination of the coordination chemistry of ϵ-caprolactam with lanthanide trichlorides reveals that cationic ϵ-caprolactam-solvated complexes of two types can be obtained from acetonitrile depending on the size of the metal. The larger lanthanides Ce, Nd, Pr, and Sm form capped octahedral dications, [Ln(C6H11NO)6Cl]+2, with the chloride ligand in the capping position. The smaller metals Eu, Gd, and Ho form trans-octahedral monocations [Ln(C6H11NO)4Cl2]+. Chloride ions are the counteranions in both cases.

The utility of N-methylimidazole and acetonitrile as solvents for the direct reaction of europium with alcohols including the first example of acetonitrile as a µ-η1:η1-bridging ligand

N-Methylimidazole and acetonitrile are suitable solvents for the direct reactions of europium metal with 2,6-Me2C6H3OH and 2,6-Pri2C6H3OH, which lead to crystallographically characterizable (N-methylimidazole)3Eu(µ-OC6H3Me2-2,6)3Eu(N-methylimidazole)2(OC6H3Me2-2,6) 1 and [(MeCN)2(2,6-Pri2C6H3O)Eu]2(µ-OC6H3Me2-2,6)2(µ-NCMe) 2, a complex which contains a µ-η1-acetonitrile ligand.

Substituent effects in the formation of aryloxide-bridged europiumcomplexes

The reactivity of europium in liquid ammonia with 2,6-disubstituted phenols has been surveyed and the effect of the 2,6 substituents on the bridging ability of the aryloxides has been examined. Monomeric and tetrameric complexes of Eu II have been isolated with tert-butyl and isopropyl substituents, Eu(OC 6 H 3 Bu t 2 -2,6) 2 (NCMe) 4 1 and Eu 4 (µ-OC 6 H 3 Pr i 2 -2,6) 4 (OC 6 H 3 Pr i 2 -2,6) 2 (µ 3 -OH) 2 (NCMe) 6 2, respectively, which can be compared to the previously reported bimetallic complex, (dme) 2 Eu(µ-OC 6 H 3 Me 2 -2,6) 3 Eu(OC 6 H 3 Me 2 - 2,6)(dme) 3, isolated with methyl substituents (dme = 1,2-dimethoxyethane). Acetonitrile has been found to be an excellent solvating ligand for the formation of crystalline complexes in this series. Complex 1 crystallizes from acetonitrile in the monoclinic space group P2 1 /c with a = 11.7117(14), b = 17.616(2), c = 18.263(2) A, β = 91.318(8)°, U = 3766.8(7) A 3 and D c = 1.282 Mg m -3 for Z = 4. Complex 2 crystallizes from acetonitrile in the monoclinic space group P2 1 /n with a = 13.676(3), b = 20.325(4), c = 32.632(6) A, β = 91.068(12)°, U = 9069(3) A 3 and D c = 1.429 Mg m -3 for Z = 4.