Substituent effects in the formation of aryloxide-bridged europium complexes

Abstract

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) 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) Å, β = 91.318(8)Њ, U = 3766.8(7) Å 3 and D c = 1.282 Mg m Ϫ3 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) Å, β = 91.068(12)Њ, U = 9069(3) Å 3 and D c = 1.429 Mg m Ϫ3 for Z = 4.

Tuning Metal Stoichiometry in Heterometal Alkoxides: First Structurally Characterised Molecular Precursor to BaZrO3

“…3 rapidly looses the crystallinity upon removal of the mother liquor, even under a cold stream of nitrogen which precluded a single crystal X-ray diffraction study. [16] and [Nd 4 (µ 3 -OH) 2 (µ 2 ,µ 1 -acac) 6 (acac) 4 ]. [17] Whereas the doubly bridging Heterometal aggregates supported by oxo-or hydroxooxygen atoms [O(2) and O (3)] are nearly planar (sum of assembling ligands are intermediates to oxide ceramics and angles ϭ av.…”

“…The gross structural fea-S. M. thanks the Alexander von Humboldt Foundation (Germany) tures of the oxo-metalate framework in 4 are comparable for a research fellowship. with other compounds adopting an M 4 O 16 edge-shared octahedral arrangement [e.g., Ti 4 (OEt) 16 , [14] W 4 (OEt) 16 [15] ], Experimental Section however, the solvating 2-propanol molecules in 4 provide…”

Molecular design approach to a highly soluble and volatile bimetallic alkoxide of late transition metal and zirconium. Synthesis, X-ray single crystal and mass-spectral study of NiZr2(acac)(OiPr)9

“…In the spectrum of 1 (see Fig. 2) one can see clearly the fragmentation series originating form the initial NiZr 2 (acac)(O i Pr) 9 (g) molecule through the loss of the terminal fragments, such as alkoxide groups or acac-ligand (the ions like [NiZr 2 (acac)(OR) 8 positively charged fragment (in contrast to non-existing hypothetical [Zr 2 (OR) 9 ] À ), consisting of two face-sharing octahedra, cannot be denied (its fragmentation series can be identified clearly in Fig. 2).…”

“…The stability of the tetrahedral coordination for nickel(II) is lower than that, for cobalt(II) and it seemed reasonable to look for a possible structure type, involving an octahedral position available for nickel. The triangular M 3 (l-OR) 2 (l-OR) 3 core appeared as the most appropriate found in the structures of many heterometallic isopropoxides of zirconium, such as Cu(II)Zr 2 Cl(O i Pr) 9 [2], LnZr 2 -(OPr i ) 9 Cl 2 (Ln = Er, Yb) [8] etc. The nickel(II) atom, included into this structure core along with two zirconium atoms, then needed two additional donor atoms and one negative charge unit to satisfy its charge and coordination.…”

Isolation and structural characterization of the first homoleptic lanthanide–zirconium oxoisopropoxide, La2Zr3O(OPri)16. Combination of an [M4O] tetrahedron with an [MO6] octahedron – A new structure type for pentanuclear alkoxide complexes

“…Only its metal-oxygen core, an [Er 2 Zr 2 ] tetrahedron centered by a l 4 -O group has been reported without providing complete evidence in relation to the X-ray experiment. The completely structurally characterized species are heteroleptic compounds, involving either halide ligands, such LnZr 2 (OPr i ) 9 Cl 2 (Ln = Er, Yb) [3], {Ln II I[Zr 2 (OPr i ) 9 ] 2 } 2 (Ln II = Eu II , Sm II ) and {LnCl 2 [Zr 2 (OPr i ) 9 ] 2 } 2 (Ln = Ce, Nd, Ho) [4], cyclopentadienyl or cyclooctadienyl ligands, such as CpLn[Zr 2 (OPr i ) 9 ] 2 (Ln = Sm, Yb) [5], or carboxylate ligands, such as [GdZr 3 O(O i Pr) 10 (OAc) 3 ] 2 [6]. The molecules of halide alkoxide or cyclopentadienyl alkoxide derivatives are based on [LnZr 2 ] triangles, where Ln(II) are octahedrally coordinated, while Ln(III) have pentagonal bipyramidal coordination for Ce, Ho and Nd and octahedral coordination for Er and Yb.…”