Heterovalent Clusters:  Ln₄Se(SePh)₈ (Ln₄ = Sm₄, Yb₄, Sm₂Yb₂, Nd₂Yb₂)

Abstract

The heterovalent (2 Ln2+, 2 Ln3+) tetranuclear (DME)4Ln4Se(SePh)8 clusters (Ln = Sm, Yb, Nd(III)/Yb(II), Sm(III)/Yb(II); DME = dimethoxyethane) can be prepared either by the reduction of Se−C bonds with Ln or by the reaction of Ln(SePh)2 with elemental Se in DME. The Sm(II) compound is difficult to isolate because it slowly redissolves after precipitation. The Yb4 compound and Nd2Yb2 compounds are considerably more stable, and can be isolated in higher yield. For the Ln = Sm4, Yb4, Sm2Yb2, and Nd2Yb2 clusters, low-temperature structural characterization reveals a square array of four metal ions with a crystallographically imposed disorder that renders the Ln(II) and Ln(III) sites indistinguishable; the Nd2Yb2 compound also crystallizes in a lattice-solvated unit cell in which there are distinct Ln(II)/Ln(III) metal ions. Connecting the four metals in all structures is a selenido ligand that caps the square array of Ln ions, and pairs of SePh ligands that bridge each of the four edges, with a chelating DME ligand saturating the primary coordination sphere of the seven-coordinate Ln ions. Yb-L3 X-ray absorption edge measurements on the disordered Yb4 cluster reveal a strong bimodal white line feature that clearly indicates the presence of both Yb(II) and Yb(III) ions. Magnetic susceptibility measurements on the Yb4 cluster indicate that the material is a static, inhomogeneous mixed valent material with well-defined Yb(II) and Yb(III) ions and a crossover in the Curie−Weiss behavior at low temperatures is interpreted in terms of crystal field and antiferromagnetic interactions. These small cluster fragments represent intermediates in the stepwise formation of larger clusters, i.e., dimerization of the Ln4 in a face-to-face arrangement gives the metal core of the now familiar octanuclear Ln8E6(EPh)12 clusters.

Reductive Trapping of [(OC)5W–W(CO)5]2− in a Mixed‐Valent SmII/III Calix[4]pyrrolide Sandwich

“…[26] Structurally characterized mixed-valent lanthanoid metal organometallic compounds are very rare,s pecifically,p entaalkylcyclopentadienyl Sm (II/III) [27] and Yb (II/III) [28] [32] and two benzeneselenolate Ln (II/III) (Ln = Sm, Yb) complexes. [33] Of N-donor ligands,abulky pyrazolate Yb (II/III) , [34] ac arbazolate Sm (II/III) , [35] and ac rossbridged cyclam supported Yb (II/III) [36] [10] have demonstrated that the tetraanionic calix [4]pyrrolide has the ability to stabilize mixed-valent rare-earth metals.T he macrocyclic ligand, constraining both Ln II and Ln III atoms in the cavity to ensure au nique Ln II ···Ln III close contact, and sandwiching each metal with two h 5 bonds with ar einforcement of the coordination by two additional h 1 bonds from nitrogen atoms, may be an ideal system to accommodate mixed valent metal atoms.…”

“…[26] Structurally characterized mixed-valent lanthanoid metal organometallic compounds are very rare,s pecifically,p entaalkylcyclopentadienyl Sm (II/III) [27] and Yb (II/III) [28] complexes, for example,[ Cp* 2 Yb III (m-F)Yb II Cp* 2 ]; [28c] an indenyl [29] and two phenyl [30] Yb (II/III) complexes.M ixed valent lanthanoid metal(II/III) compounds supported by O, S, and Se donor ligands have been serendipitously isolated, including two bulky aryloxide Ln (II/III) (Ln = Yb, [31a] Eu [31b] )c omplexes, at hiophenyl Eu (II/II) , [32] and two benzeneselenolate Ln (II/III) (Ln = Sm, Yb) complexes. [33] Of N-donor ligands,abulky pyrazolate Yb (II/III) , [34] ac arbazolate Sm (II/III) , [35] and ac rossbridged cyclam supported Yb (II/III) [36] complexes have been isolated. Thei solation of rare mixed-valent lanthnoid complexes 1, 2,a nd the previously reported [(thf) 2 Sm II -(N 4 Et 8 )Sm III (m-Cl) 2 Li(thf) 2 ] [10] have demonstrated that the tetraanionic calix [4]pyrrolide has the ability to stabilize mixed-valent rare-earth metals.T he macrocyclic ligand, constraining both Ln II and Ln III atoms in the cavity to ensure au nique Ln II ···Ln III close contact, and sandwiching each metal with two h 5 bonds with ar einforcement of the coordination by two additional h 1 bonds from nitrogen atoms, may be an ideal system to accommodate mixed valent metal atoms.…”

Luminescence of Salen Lanthanide Bimetallic Complexes: Dual Emission and Energy Transfer

“…Heterometallic complexes containing two or more different lanthanide cations are attractive because of their potential to achieve multiple emissions and up‐conversion, which are useful as labels in multiplexed bioanalytical assays and as encryption tags. These materials can play an important role in applications related to national security purposes, such as tracking and identifying objects at airports, in transit, in storage, and on the battlefield 34–45…”

Synthesis and X-ray crystal structure of cationic polynuclear hydroxide acetylacetonate lanthanide(III) clusters with homodinuclear or heterodinuclear decacarbonyl hydrides: [HMo2(CO)10]− and [HCrW(CO)10]−

“…A variety of lanthanide clusters have been obtained as tetra [14,15], penta [16], hexa [15b,e,17] octa [18], nona [19] [21], the synthesis was made by hydrothermal reaction with the aid of 1,4-naphtalene dicarboxylate (1,4-NDA) that give rise to porous lanthanide polymers having a dicubane like structure of the hydroxo core that is a frequent structural motif in lanthanide hydroxo clusters. As part of our program of developing new polynuclear lanthanide oxo-cluster compounds containing transition metals [22][23][24] we report the synthesis and spectroscopic characterization of Sm 9 (acac) 16 (OH) 10 [CrW(CO) 10 (-H)] and of the compounds having general formula Ln 9 (acac) 16 (OH) 10 …”