Bridging ligands, lanthanide cyclopentadienyl

Hydrocarbonyl compounds, lanthanide complexes, 4, 4 ( -Hydrocarbyl)bis(zirconocene), preparation, 4, 906 Hydrocarbyl-bridged cyclopentadienyl-amido complexes, with Zr(IV), 4, 864 Hydrocarbyl complexes bis-Cp Ti hydrocarbyls reactions, 4, 551 structure and properties, 4, 551 synthesis, 4, 542 cobalt with rf-ligands, 7, 51 cobalt with rf-ligands, 7, 56 cobalt with ]4-ligands, 7, 59 cobalt with rf-ligands, 7, 71 heteroleptic types, 4, 192 homoleptic types, 4, 192 into magnetic metal nanoparticles via ligand stabilization, 12, 87 via polymer stabilization, 12, 87 into noble metal nanoparticles... 

Compounds with Ring-bridged Cyclopentadienyl Ligands 4.01.6.9.1 Lanthanide(n) compounds... 

Evans et al. also reported the synthesis of the divalent lanthanide COT complexes [Zr2(OPr )9Ln]2(COT) (Ln = Yb, Sm) from [Zr2(OPr )9LnI]2 and K2COT (Scheme 226). The monoanionic [Zr2(OPr )9]- unit is used as a cyclopentadienyl analog. X-ray diffraction studies show the bimetallic Ln(ll) complexes with the Sm centers coordinated to the bridging COT ligand in an -fashion.264 [Zr2(OPr )9Sm]2(COT) reacts with 1,3,5,7-COT to form the hexane-soluble Sm(m) complex [Zr2(OPr )9]Sm(COT), in a manner analogous to the reduction of COT by Cp Sm(COT). The molecular structure shows the monomeric complex with one -coordinated COT ligand and the monoanionic [Zr2(OPr )9]- unit attached to the Sm in a tetradentate fashion.2... 

The scandium, yttrium, or lanthanide atoms in these compounds evidently form such bridges to make better use of their valence shell electrons and orbitals. (C5H5)2MR monomers would contain only 14 valence shell electrons (five from each cyclopentadienyl ligand, one from the alkyl group in addition to the three metal electrons), well short of the 16 or preferably 18 valence shell electrons normally present in stable organotransition metal compounds " dimerization to (C5H5)2M(p-R)2M(C5H5)2 raises the valence shell electron count to 16 and uses a metal orbital that would be vacant in the monomer. 

---