Direct Lanthanide-Transition Metal Interactions: Synthesis of (NH(3))(2)YbFe(CO)(4) and Crystal Structures of {[(CH(3)CN)(3)YbFe(CO)(4)](2).CH(3)CN}(infinity) and [(CH(3)CN)(3)YbFe(CO)(4)](infinity)

Enhancing the Luminescence of Eu(III) Complexes with the Ruthenocene Organometallic Unit as Ancillary Ligand

Five novel Eu(III)-β-diketonate complexes containing ruthenocene ancillary ligands (1,1'-bis(diphenylphosphoryl)ruthenocene─RcBPO) were synthesized and characterized. The coordination compounds presented the general formula [Eu(β-dik)₃(RcBPO)], where β-dik stands for 2-thenoyltrifluoroacetonate (tta), 3-benzoyl-1,1,1-trifluoroacetone (btf), 2-dibenzoylmethanate (dbm), 2-acetyl-1,3-indandionate (aind), and 2-benzoyl-1,3-indandionate (bind), and RcBPO stands for 1,1'-bis(diphenylphosphoryl)ruthenocene. The [Eu(aind)₃(RcBPO)] complex crystallizes in a monoclinic Cc non-centrosymmetric space group with the europium site environment, assuming a bicapped trigonal prism coordination polyhedron with the symmetry point group close to C_2v. Photoluminescent properties for the solid-state samples were described in terms of excitation, emission, lifetime decay curves, and intrinsic and overall quantum yields. The replacement of the two coordinated H₂O molecules by the RcBPO ancillary ligand leads to great enhancements of the overall quantum yields (Q_Eu^L), with the minimum increment by a factor of 5 for the case of [Eu(btf)₃(RcBPO)] and the maximum enhancement of 270 times for the case of the [Eu(dbm)₃(RcBPO)] complex. In addition, theoretical calculations were carried out to model the spectroscopic properties of the investigated compounds. To obtain theoretical Judd-Ofelt parameters (Ω_λ, λ = 2, 4, and 6) and intramolecular energy transfer rates, the JOYSpectra web platform was employed using the structure obtained from density functional theory calculations. Hence, a rate equation model provided theoretical overall quantum yields, which are in great agreement with measured data.

Rare earth–metal bonding in molecular compounds: recent advances, challenges, and perspectives

In this review, all structurally authenticated molecular compounds with direct bonds between rare earth metals and transition or main group metals are summarized. Novel aspects of their syntheses, properties and reactivities are highlighted.

Analysis of crystallographic and structural data of polymeric FeM (M = transition metals, lanthanides) complexes

This review covers crystallographic and structural data for almost fifty polymeric FeM complexes (M = transition Cu, Ag, Au, Mo, W, Mn, Co, Ni and Pt and lanthanide elements Sm, Er and Yb) where iron is involved in polymeric chains. The complexes are for the most part yellow or black, but there are complexes of brown, orange, red, purple, blue and green colour. The complexes crystallized in the monoclinic (by far prevails), triclinic, tetragonal, orthorhombic, trigonal, hexagonal and rhombohedral crystal classes. The iron atoms are found in oxidation states 0, +2 and +3, of which +3 by far prevails. The inner coordination spheres about the Fe(0) atom are tetrahedral (FeC4) or sandwiched (FeC10), Fe(II) atoms are six-coordinated, and Fe(III) are six or even seven-coordinated. The inner coordination about M atoms range from four- through six- to eight-coordinated. The shortest Fe-Fe, Fe-M (transition) and Fe-M (lanthanide) and M-M separations are: 8.08 Å, 3.033 Å for Fe-Cu, 3.010 Å for Fe-Yb and 2.505 Å for Mo-Mo.

catena-Poly[[[tetraaquaerbium(III)]-μ-oxalato-κ4O1,O2:O1′,O2′] [bromidobis(pyrazine-2-carboxylato-κ2N1,O)cuprate(II)] tetrahydrate]

In the title heterometallic complex, {[Er(C₂O₄)(H₂O)₄][CuBr(C₅H₃N₂O₂)₂]·4H₂O}_n, the Er^III atom is eight-coordin­ated by four O atoms from two centrosymmetric oxalate ligands and four water mol­ecules, displaying a bicapped trigonal-prismatic geometry. The oxalate ligands bridge the Er atoms into a polymeric cationic chain along [110]. The Cu^II atom is five-coordinated in a square-pyramidal geometry by two pyrazine-2-carboxyl­ate ligands and a Br atom, forming a discrete anion. The polymeric cations, complex anions and uncoordinated water mol­ecules are self-assembled into a three-dimensional supra­molecular network through O—H⋯N, O—H⋯O and O—H⋯Br hydrogen bonds.

Square structures and photophysical properties of Zn(2)Ln(2) complexes (Ln = Nd, Eu, Sm, Er, Yb)

Heterotetranuclear Zn(2)Ln(2) (Ln = Nd , Eu , Sm , Er , Yb ) complexes {Zn(2)(Mq)(2)(tpyO)(2)}{(Ln(hfac)(3))(2)} (HMq = 2-methyl-8-hydroxylquinoline, tpyOH = [2,2':6'2'']terpyridin-4'-ol, hfac = hexafluoroacetylacetonate) display novel square structures ligated by bifunctional ligands tpyO (mono- and tridentate) and Mq (chelating and bridging mu-phenoxo). These compounds exhibit sensitized lanthanide emission upon photo-excitation of ZnMq/tpy antenna chromophores. By virtue of the dual luminescence with complementary colors, the ZnMq/tpyO-based cyan emission and Sm(III)-centered orange luminescence are combined to generate a white-light emission in Zn(2)Sm(2) (4) complex.

Non-traditional ligands in f-block chemistry

The molecular chemistry of the f-elements, i.e. the lanthanides and actinides, is traditionally dominated by the use of carbon, nitrogen, oxygen or halide ligands. However, the use of metal-based fragments as ligands is underdeveloped, which contrasts to the field of d-block metal–metal complexes that have developed extensively over the last 50 years. Consequently, the use of metal-based fragments as ligands to the f-elements may be regarded as ‘non-traditional’. This review outlines the development of compounds that possess f-element–metal bonds that may be described as polarized covalent or donor–acceptor in nature. For this review, the f-element is defined as (i) a group 3 or lanthanide metal: scandium, yttrium and lanthanum to lutetium or (ii) an actinide metal: thorium or uranium, and the metal is defined as a d-block transition metal, or a p-block triel (group 13, aluminium or gallium), a tetrel (group 14, silicon, germanium or tin), or a pnictide (group 15, antimony or bismuth) metal. Silicon, germanium and antimony are traditionally classified as metalloids, but we include them in this review for completeness. This review focuses on complexes that have been unambiguously structurally authenticated by single crystal X-ray diffraction studies, and novel aspects of their syntheses, properties and reactivities are highlighted.