Cluster polynuclear lanthanide complexe

Two kinds of salen-type Schiff-base ligands, conjugated and flexible, have been used in the synthesis of polynuclear lanthanide complexes and lanthanide coordination polymers Lanthanides Coordination Chemistry, Rare Earth Metal Cluster Complexes. The stoichiometry and structures of these complexes are dependent on the Schiff-base... 

We can see so many lanthanide clusters behave as efficient SMMs in those p -O-fixed complexes. Especially, the energy barrier record (530 K) for polynuclear lanthanide SMMs, held by the p5-0-fixed Dy5 with a square-based pyramid, has not been broken by the end of 2013. Such a structural characteristic should support the isolation of a robust SMM to a great extent, which provides a change to explore new methods for achieving SMMs with high barriers. 

Amino acid is one of the most important biological ligands. Researches on the coordination of metal-amino acid complexes will help us better understand the complicated behavior of the active site in a metal enzyme. Up to now many Ln-amino acid complexes [50] and 1 1 or 1 2 transition metal-amino acid complexes [51] with the structural motifs of mononuclear entity or chain have been synthesized. Recently, a series of polynuclear lanthanide clusters with amino acid as a ligand were reported (most of them display a Ln404-cubane structural motif) [52]. It is also well known that amino acids are useful ligands for the construction of polynuclear copper clusters [53-56], Several studies on polynuclear transition metal clusters with amino acids as ligands, such as [C03] [57,58], [Co2Pt2] [59], [Zn6] [60], and [Fe ] [61] were also reported. 

Reduction of dinitrogen molecule by divalent lanthanide complexes has been a popular subject in coordination and organometallic chemistry of the lanthanide elements. In the course of these studies, a large number of polynuclear lanthanide clusters featuring a core of lanthanide atoms organized around a dinitrogen unit have been obtained and structurally characterized. 

The chemistry of polynuclear lanthanide componnds (see Rare Earth Metal Cluster Complexes) conslmcted with... 

Lanthanides in Living Systems Lanthanides Coordination Chemistry Lanthanides Luminescence Applications Lmninescence Lanthanides Magnetic Resonance Imaging Lanthanide Oxide/Hydroxide Complexes Carboxylate Lanthanide Complexes with Multidentate Ligands Rare Earth Metal Cluster Complexes Supramolecular Chemistry from Sensors and Imaging Agents to Functional Mononuclear and Polynuclear Self-Assembly Lanthanide Complexes. 

The replacement of groups with weak coordination interaction, including substitution of the edge and terminal ligands, plus the alteration of lanthanides, may be of help in the design and synthesis of a large variety of 3d-4f clusters. This approach is attractive and it may open up new routes for the construction of other polynuclear complexes. A similar situation also applies to analogous Zn2+ and Co2+ clusters. 

The only relevant Group 3 polynuclear complex, [Y8(/i4—0)(/i3—OH)i2(/r—Se4)4Cl2(DMF)i0] 6DMF is prepared from YC13 and polyselenide in DMF. It has an octanuclear core, supported by oxo, hydroxo, and tetraselenido bridges with no Y—Y bonds. No Sc or actinide chalcogenide clusters are known. Lanthanide/selenido clusters have recently been isolated.14... 

The second t)q)e of cluster compounds of the lanthanide alkoxides features one or several small-unit, inorganic ligands including oxo, hydroxo, halo, and other groups as part of the cluster core structure. Frequently, a combination of such ligands is foimd in the same cluster species. In a sense, this "central spherical charge density" drives the assembly of the polynuclear complexes without their participation, no clusters are formed or species of completely different structures result. 

Metal thiolate complexes will reduce elemental sulfur or red selenium via the oxidative elimination of RSSR. In a similar manner, metal selenolate complexes ean be used to reduce elemental selenium. The resulting E ligands favor the formation of polynuclear cluster complexes, due to the greater tendency of E (vs. RE ) to form bridging interactions between metal centers. Originally developed in the synthesis of [Fe4Se4(SPh)4], this method has been well utilized in the synthesis of a number of iron thiolate/sulfide clusters, as well as their selenide counterparts (Equation (5)). More recently, sulfur- and selenium-containing lanthanide clusters (see Section 7.2.5.5) have been synthesized by the displacement of ER from Ln(ER)3 ... 

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