The Scandium(II) Carbonyl Complex (C₅H₂^tBu₃)₂Sc(CO) and Its Isocyanide Analog (C₅H₂^tBu₃)₂Sc(CNC₆H₃Me₂-2,6)

Treatment of the scandium(II) metallocene Cp^ttt₂Sc (Cp^ttt = C₅H₂^tBu₃) with CO or the isocyanide CNXyl (Xyl = C₆H₃Me₂-2,6) yields the carbonyl complex Cp^ttt₂Sc(CO), 1, or the isocyanide complex Cp^ttt₂Sc(CNXyl), 2, which were identified by X-ray crystallography. Isotopic labeling with ¹³CO shows the CO stretch of 1 at 1875 cm^-1 shifts to 1838 cm^-1 in 1-¹³CO. The CN stretch in 2 is shifted to 1939 cm^-1 compared to 2118 cm^-1 for the free isocyanide. The 80.1 MHz (28.7 G) ⁴⁵Sc hyperfine coupling in 1 and 74.7 MHz (26.8 G) in 2 are similar to the 82.6 MHz (29.6 G) coupling constant in Cp^ttt₂Sc and indicate that 1 and 2 are Sc(II) complexes. A comprehensive analysis of the electronic structures of 1 and 2 using DFT calculations is reported.