No abstract

A novel C s -symmetric yttrocene complex, ansa-Me 2 Si(η 3 -Flu)(η 5 -Cp′)YCl 2 Li(OEt 2 ) 2 (3; Flu ) C 13 H 8 , fluorenyl; Cp′ ) C 5 Me 4 ), has been prepared via a salt metathesis reaction from anhydrous YCl 3 and the dilithium salt of the ligand ansa-Me 2 Si(FluH)(Cp′H). Treatment of 3 with NaN(SiMe 3 ) 2 gave the corresponding bis(trimethylsilyl)amide derivative ansa-Me 2 -Si(Flu)(η 5 -Cp′)YN(SiMe 3 ) 2 (4). The X-ray structure of 3 reveals unusual η 3 -fluorenyl coordination to the Y 3+ ion. In 4, the Y-Flu bonding being partially slipped toward η 3 from η 5 , π-dative bonding nature in the Y-N bond and a direct interaction of the Y atom with one methyl group of the N(SiMe 3 ) 2 fragment are present. Both compounds constitute the first examples of structurally characterized fluorenyl ansa-yttrocenes. The neutral compound 4 is active for the polymerization of methyl methacrylate (MMA) in toluene, affording isorich poly(MMA)s.

The lifetime and diffusion distance of singlet oxygen in air at 23 °C under 1 atm are 2.80 seconds and 0.992 cm, far longer than previously reported.