Reactivity of “Eu(OⁱPr)₂” with Phenols:  Formation of Linear Eu₃, Square Pyramidal Eu₅, Cubic Eu₈, and Capped Cubic Eu₉ Polymetallic Europium Complexes

Abstract

The direct reaction of europium with 2-propanol and phenols has been investigated under a variety of conditions. The reaction of europium metal with 2,6-dimethylphenol and 2,6-diisopropylphenol in 2-propanol at reflux revealed that polymetallic europium complexes could be generated by this method. Hx[Eu8O6(OC6H3Me2-2,6)12(OiPr)8], 1, and H5[Eu5O5(OC6H3iPr2-2,6)6(NCCH3)8], 2, were isolated by recrystallization in the presence of hexanes and acetonitrile, respectively, and characterized by X-ray crystallography. Complex 1 has a cubic arrangement of europium ions with face-bridging mu 4-O donor atoms, edge-bridging mu-O(phenoxide/phenol) ligands, and terminal O(isopropoxide/2-propanol) ligands. Complex 2 is mixed valent and has a square pyramidal europium core with four Eu(II) ions at the basal positions and one Eu(III) ion at the apex. Since these reactions gave complicated mixtures of products from which 1 and 2 could only be obtained in low yields, direct reactions under less forcing reaction conditions were investigated. Europium reacts slowly at room temperature to form arene-soluble divalent [Eu(OiPr)2(THF)x]n, 3. Complex 3 reacts with 2,6-dimethylphenol to form the arene-insoluble complex (H[Eu(OC6H3Me2)2(OiPr)])n, 4. Recrystallization of 4 in the presence of THF results in the crystallographically characterizable divalent trimetallic complex [Eu(OC6H3Me2-2,6)2(THF)2]3, 5, which has an unusual linear metal geometry. In the presence of HOiPr at ambient conditions in the glovebox, crystals of 5 slowly convert to the mixed valent H10[Eu8O8(OC6H3Me2-2,6)10(OiPr)2(THF)6], 6, which was found to have a cubic arrangement of europium atoms similar to 1 by X-ray crystallography. Complex 4, upon heating under vacuum, followed by reaction with THF, forms the arene-soluble divalent complex H18([Eu9O8(OC6H3Me2-2,6)10(THF)7][Eu9O9(OC6H3Me2-2,6)10(THF)6]), 7, which contains two types of capped cubic arrangements of europium ions in the solid state.

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

“…Other solvents were dried and physical measurements were made as previously described. [15] Magnetic moments were measured by the method of Evans [30] with a General Electric QE300 NMR spectrometer. Elemental analyses were performed by Desert Analytics, Tucson, AZ with metal analyses done by atomic absorption spectroscopy.…”

Rare‐Earth Metal Oxo/Hydroxo Clusters – Synthesis, Structures, and Applications

“…[10,[49][50][51][52][53][54][55] According to Evans et al, the reaction between europium metal and 2,6-diisopropylphenol in propan-2-ol leads to the formation of pentanuclear complex H 5 [Eu 5 O 5 (OC 6 H 3 iPr 2 -2,6) 6 -(NCCH 3 ) 8 ] after recrystallization from acetonitrile. [56] This mixedvalence compound features the known square pyramidal cluster core with four Eu II ions at the basal positions and one Eu III ion at the apex. [56] By formally connecting two of these square pyramidal polyhedra at the apical rare-earth metal atom, a cluster core with nine metal centers can be obtained (Scheme 2).…”

“…[56] This mixedvalence compound features the known square pyramidal cluster core with four Eu II ions at the basal positions and one Eu III ion at the apex. [56] By formally connecting two of these square pyramidal polyhedra at the apical rare-earth metal atom, a cluster core with nine metal centers can be obtained (Scheme 2). In the resulting double pyramid, the two square faces are aligned parallel and they adopt a staggered conformation providing D 4d symmetry.…”

Synthesis and Structural Characterization of Tetra‐ and Pentanuclear Lanthanide Hydroxido Clusters

“…One way to obtain these compounds is the hydrolysis of moisture-sensitive starting material, [11,12] whereas the other approach is a hydrolytic one in which the water molecules are deprotonated in a controlled way. [13][14][15][16][17][18] Most of the oxido/hydroxido clusters are stabilized by ligands such as alkoxides, [19,20] phenoxides, [21] diketones, [22,23] and more recently amino acids [7,24] and the o-nitrophenolato ligand.…”