Synthesis and structural characterization of lanthanum and cerium substituted cyclopentadienyl borohydride complexes

Abstract The lanthanide borohydrides [Ln(BH 4 ) 3 (THF) n ] [Ln = La, n = 4 ( 1 ); Ln = Ce, n = 3.5] were treated with the substituted cyclopentadienyl potassium transfer agents KCp tt (Cp tt  = C 5 H 3 t Bu 2 -1,3), KCp ttt (Cp ttt  = C 5 H 2 t Bu 3 -1,2,4) and KCp′′′ (Cp ′′′  = C 5 H 2 (SiMe 3 ) 3 -1,2,4) in various reaction conditions to yield the heteroleptic lanthanide complexes [La(Cp tt ) 2 (μ-BH 4 )] 2 ( 2 ), [La(Cp ttt )(BH 4 ) 2 (THF) 2 ] ( 3 ), [La(Cp ttt )(μ-BH 4 ) 2 ] 6 ( 4 ), [Ce(Cp ttt )(BH 4 )(μ-BH 4 )(THF)] 2 ( 5 ), [La(Cp ttt ) 2 (BH 4 )] ( 6 ) and [Ln(Cp) 2 (BH 4 )(THF)] (Ln = La, 7 ; Ce, 8 ) by salt metathesis protocols. Complexes 1–8 have been variously characterized by single crystal X-ray diffraction, multi-nuclear NMR and FTIR spectroscopies, and elemental analyses.