First Chemical Transformations of Lanthanide Borohydride Compounds:  Synthesis and Crystal Structures of [(η-C₈H₈)Nd(BH₄)(THF)]₂ and [(η-C₈H₈)Nd(THF)₄][BPh₄]

Reaction of Nd(BH4)3(THF)3 with K2COT (COT = η-C8H8) in tetrahydrofuran (THF) gave the first (cyclooctatetraene)lanthanide borohydride, (COT)Nd(BH4)(THF)2 (1). By treatment with NHEt3BPh4, 1 was transformed into [(COT)Nd(THF)4][BPh4] (3), a unique example of a (cyclooctatetraene)lanthanide cation; both 1 and 3 gave (COT)Nd(Cp*)(THF) (Cp* = η-C5Me5) upon reaction with KCp*.