Flash Communication: A Sc(II) Pentamethylcyclopentadienyl Complex is Isolable as an Isocyanide Adduct, Cp* ₂ Sc(CNC ₆ H ₃ -2,6-Me ₂ ) ₂ , by Dinitrogen Elimination

A Sc(II) pentamethylcyclopentadienyl (Cp*) complex such as “Cp*2Sc” has not been isolable, although the Sc(II) metallocenes, Cpttt2Sc (Cpttt = C5H3tBu3) and (C5Me4SiMe2tBu)2Sc can be crystallographically characterized and Cpttt2Sc forms the Sc(II) CO and CNR adducts Cpttt2Sc(CO) and Cpttt2Sc(CNXyl) (Xyl = C6H3-2,6-Me2). However, the dark-teal Sc(II) metallocene Cp*2Sc(CNXyl)2 can be isolated from the Sc(III) reduced dinitrogen complex (Cp*2Sc)2(μ-η1:η1-N2) through its reaction with 2 equiv of CNXyl. Density functional theory analysis based on the X-ray crystal structure is used to evaluate the electronic structure of this complex, which allows its isolation, and the low 36.3 MHz (13.0 G) hyperfine coupling in the eight-line EPR spectrum of Cp*2Sc(CNXyl)2.