Cerocene and Lanthanocene Chalcogenides: Synthesis, Structure, and Luminescence.

A series of lanthanide chalcogenides {[η 5 -1,3-(Me 3 C) 2 C 5 H 3 ] 2 Ln} 2 (μ-η 2 :η 2 -Te 2 ) (Ln = Ce 1 , La 2 ), {[η 5 -1,3-(Me 3 C) 2 C 5 H 3 ] 2 Ln(THF)} 2 (μ-Se) (Ln = Ce 3 , La 4 ), and {[η 5 -1,3-(Me 3 C) 2 C 5 H 3 ] 2 Ln(THF)} 2 (μ-Te) (Ln = Ce 5 , La 6 ) can be readily obtained by the reaction of the alkyl complexes [η 5 -1,3-(Me 3 C) 2 C 5 H 3 ] 2 Ln(CH 2 C 6 H 4 - o -NMe 2 ) with elemental selenium or tellurium in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN). The reaction of the alkyl complexes [η 5 -1,3-(Me 3 C) 2 C 5 H 3 ] 2 Ln(CH 2 C 6 H 4 - o -NMe 2 ) with 9-BBN in 1:2 molar ratio afforded the lanthanide (cyclooctane-1,5-diyl)dihydroborate complexes [η 5 -1,3-(Me 3 C) 2 C 5 H 3 ] 2 Ln[(μ-H) 2 BC 8 H 14 ] (Ln = Ce 7 , La 8 ) concomitant with the (Me 2 N- o -C 6 H 4 CH 2 )BC 8 H 14 release, indicating that [η 5 -1,3-(Me 3 C) 2 C 5 H 3 ] 2 LnH may be the reactive species for the synthesis of lanthanide chalcogenides. All the new compounds were characterized by various spectroscopic methods, and their solid-state structures were further confirmed by single-crystal X-ray diffraction analyses. Luminescence spectroscopy was also employed to characterize complexes 1-6 . The Ce(III) complexes 3 and 5 display distinct luminescence properties at room temperature, as compared to the corresponding La(III) complexes 4 and 6 . The complex {[η 5 -1,3-(Me 3 C) 2 C 5 H 3 ] 2 Ce(THF)} 2 (μ-Te) ( 5 ) exhibits unexpectedly red emission in solution which is found to depend strongly on the excitation wavelength.