Two new indene compounds, C9H7CH2SiMe2NC4H8 (1) and C9H6-1-Me-3-CH2SiMe2NC4H8 (2), were synthesized by the reaction of C9H6RLi (R) H, Me) with ClCH2SiMe2Cl, followed by treatment with lithium pyrrolidinide C4H8NLi. The interaction of [(Me3Si)2N]3Eu(μ-Cl)-Li(THF)3 with 2 equiv of 1 in refluxing toluene produced, after workup, a novel triple-decker sandwich tetranuclear europium(Ⅱ) compound, [{η:5η:5η1-(C9H5CH2SiMe2NC4H8)2}Eu2(μ-Cl)]2-[μ-η3:η5:η1:η3:η5:η1-(C9H5CH2SiMe2NC4H8)2]âC7H8â(C6H6)0.5 (3), with a coupled indenyl ligand through tandem silylamine elimination, reduction of Eu3+ to Eu2+, and the C-C coupling reactions. To probe the formation pathway of complex 3, the interaction of C9H6-1-Me-3-CH2SiMe2NC4H8 (3) with [(Me3Si)2N]3Eu(μ-Cl)Li(THF)3 was studied. Treatment of [(Me3-Si)2N]3Eu(μ-Cl)Li(THF)3 with 2 equiv of 2 in refluxing toluene temperature or at 60℃ produced, after workup, a monomeric europium(Ⅱ) complex, (η5:η1-C9H5-1-Me-3-CH2SiMe2-NC4H8)2Eu (4), via tandem silylamine elimination/homolysis of the Eu-N bond reactions. The formation pathway for complex 3 was proposed. All the compounds were fully characterized by spectroscopic methods and elemental analyses, and the structures of complexes 3 and 4 were additionally determined by single-crystal X-ray diffraction analyses. It was found that complexes 3 and 4 can function as single-component MMA polymerization initiators, which represent the first examples of europium(Ⅱ) complexes as single-component MMA polymerization catalysts. The solvents and temperature effects' on the activities of the catalysts were also discussed.

Several new 13-vertex closo-metallacarboranes of rare earths incorporating nido-and arachno-carborane ligands have been prepared and structurally characterized. They represent a new class of metallacarboranes bearing a h7-carboranyl ligand recently discovered in our laboratory. This work indicates that the substituents on carborane cage carbons may affect the overall molecular structures of the resultant 13-vertex closo-metallacarborane complexes, but have little influence on the interactions between the central metal ion and nido- or arachno-carborane ligand.

A versatile compound, Me2Si(C9H7)(C2B10H11) can be conveniently converted into the monoanion [Me2Si(C9H6)(C2B10H11)]Na, the dianion [Me2Si(C9H6)(C2B10H10)]Na2, and the trianion [Me2Si(C9H6)(C2B10H11)]K3 by treatment with 1 equiv or excess amounts of NaH or K metal in THF, respectively. Reaction of LnCl3 with 1 equiv of [Me2Si(C9H6)(C2B10H11)]Na in THF gave dichloride complexes [η5-Me2Si(C9H6)(C2B10H11)]LnCl2(THF)3 (Ln) Nd (1), Er (2)). They can further react with another equivalent of [Me2Si(C9H6)(C2B10H11)]Na to afford monochloride complexes [η5-Me2Si(C9H6)(C2B10H11)]2LnCl(THF)2 (Ln) Ce (3), Nd (4), Sm (5), Er (6)), which can also be prepared by treatment of LnCl3 with 2 equiv of [Me2Si(C9H6)-(C2B10H11)]Na in THF. 4 reacts with excess NaH in THF to produce [Na(THF)6][{η5:σ-Me2-Si(C9H6)(C2B10H10)}2Nd] (7), which can also be prepared from the reaction of NdCl3 with 2 equiv of [Me2Si(C9H6)(C2B10H10)]Na2 in THF. Treatment of 2 with 2 equiv of K metal at room temperature yielded [η5:η6-Me2Si(C9H6)(C2B10H11)]Er(THF)2 (8). Reaction of 6 with 1 equiv of NaH afforded [{η5:σ-Me2Si(C9H6)(C2B10H10)}{η5-Me2Si(C9H6)(C2B10H11)}]Er(μ-Cl)-Na(THF)3 (9), which can also be prepared from the reaction of 2 with 1 equiv of [Me2Si-(C9H6)(C2B10H10)]Na2 in THF. Treatment of 9 with a mixture of 1 equiv of NaOH and excess NaH in THF generated the dinuclear complex [Na2(THF)11][{η5:σ-Me2Si(C9H6)(C2B10H10)}-{μ-η5:σ-(C9H6)SiMe2O}Er]2 (10). Treatment of Me2Si(C9H7)(C2B10H11) with excess NaH in THF under UV-light followed by reaction with 1 equiv of LnCl3 resulted in the isolation of unprecedented biscarborane compounds [LnCl2(THF)5][μ-CH-(closo-C2B10H11)-nido-CB10H11] (Ln) Er (11), Y (12)). All of these complexes were characterized by various spectroscopic and elemental analyses. The solid-state structures of 7 and 9-12 were confirmed by singlecrystal X-ray analyses.

Reaction of Me2Si(C9H7)Cl with 1 equiv of Li2C2B10H10 gave, after hydrolysis, the new versatile ligand Me2Si(C9H7)(C2B10H11) (1). 1 can be conveniently converted into the monoanion [Me2Si(C9H6)(C2B10H11)]-(2) and the dianion [Me2Si(C9H6)(C2B10H10)]2-(3) by treatment with 1 equiv or excess amounts of NaH, respectively. Treatment of SmI2 with 2 in THF gave the unexpected redox product [η5:η6-Me2Si(C9H6)(C2B10H11)]Sm(THF)2 (4). Reaction of SmI2 with 1 equiv of 3 in THF, followed by reaction with 2, gave the unexpected C-H bond reduction product [{η5:σ-Me2Si(C9H6)(C2B10H10)}2Sm][Na(THF)6] (5). In contrast, reaction of YbI2 with 1 or 2 equiv of 2 afforded [{η5-Me2Si(C9H6)(C2B10H11)}Yb(σ-I)(THF)2]2 (6) or [η5-Me2Si(C9H6)(C2B10H11)]2Yb(THF)2 (7), respectively. Treatment of YbI2 with 1 equiv of 3 in THF gave [η5:σ-Me2Si(C9H6)(C2B10H10)]Yb(THF)3 (8), which is the first mixed-ligand organolanthanide(II) complex containing both Ln-C ð and ó bonds to be reported. 8 can also be prepared from the reaction of 6 with excess NaH in THF. Reaction of 8 with 1 equiv of 2 in THF yielded [η5-Me2Si(C9H6)(C2B10H11)]Yb(THF)[(μ-η5):σ-Me2Si(C9H6)(C2B10H10)]Na-(THF)3 (9), which can also be prepared by reaction of 7 with 1 equiv of NaH in THF. These new complexes have been fully characterized by 1H, 13C, and 11B NMR, IR spectroscopy, and elemental analyses. The molecular structures of 4, 5, 8, and 9 have been further confirmed by single-crystal X-ray analyses.

Reaction of Me2Si(C5H5)Cl with 1 equiv of Li2C2B10H10 in toluene/ether at 0℃, after hydrolysis, gave Me2Si(C5H5)(C2B10H11) (1) in 79% isolated yield. 1 can be conveniently converted into the monoanion [Me2Si(C5H4)(C2B10H11)]Na (2), the dianion [Me2Si(C5H4)-(C2B10H10)]Li2 (3), and the trianion [Me2Si(C5H4)(C2B10H11)]K3 (4) by treatment with NaH, MeLi, and K metal in THF at room temperature, respectively. 2 reacted with 1 equiv of LnCl3 in THF to give [η5-Me2Si(C5H4)(C2B10H11)]LnCl2(THF)3 (Ln) Nd (5), Sm (6), Er (7), Yb (8)) in good yield. Treatment of LnCl3 with 2 equiv of 2 or reaction of [è5-Me2Si(C5H4)-(C2B10H11)]LnCl2(THF)3 with an equimolar amount of 2 in THF resulted in the isolation of [η5-Me2Si(C5H4)(C2B10H11)]2LnCl(THF)2 (Ln) Nd (9), Sm (10), Y (11), Gd (12), Yb (13)) in good yield. Interaction of 3 with LnCl3 in THF in a molar ratio of 1∶1 or 2∶1 or reaction of [η5-Me2Si(C5H4)(C2B10H11)]2LnCl(THF)2 with 2 equiv of MeLi in THF gave the same compounds [{η5:σ-Me2Si(C5H4)(C2B10H10)}2Ln][Li(THF)4] (Ln) Nd (14), Y (15), Er (16), Yb (17)). Treatment of NdCl3 with an equimolar amount of 4 in THF or reaction of [η5-Me2Si-(C5H4)(C2B10H11)]NdCl2(THF)3 with excess K metal in THF produced [η5:η6-Me2Si(C5H4)-(C2B10H11)]Nd(THF)2 (18). Under similar reaction conditions, however, interaction of LnCl3 (Ln) Sm, Yb) with 4 in THF afforded the organolanthanide(Ⅱ) compounds {[η5:η6-Me2Si-(C5H4)(C2B10H11)]LnII(THF)2}{K(THF)2} (Ln) Sm (20), Yb (21)). The Sm analogue of 18, [η5:η6-Me2Si(C5H4)(C2B10H11)]Sm(THF)2 (19), was prepared from an unprecedented redox reaction of SmI2 with 2 equiv of 2 in THF. Reaction of 19 with excess K metal in THF gave 20. Unlike the SmI2 case, interaction of YbI2 with 2 equiv of 2 in THF gave [η5-Me2Si(C5H4)-(C2B10H11)]2YbII(THF)2 (22). All of these compounds were characterized by various spectroscopic and elemental analyses. The solid-state structures of compounds 5, 8, 9, 10, 14, 15, 16, 17, 19, and 22 were confirmed by single-crystal X-ray analyses. The reaction mechanism of the formation of 19 is also proposed.