The Scandium(II) Carbonyl Complex (C 5 H 2 t Bu 3 ) 2 Sc(CO) and Its Isocyanide Analog (C 5 H 2 t Bu 3 ) 2 Sc(CNC 6 H 3 Me 2 -2,6).

Treatment of the scandium(II) metallocene Cp ttt 2 Sc (Cp ttt = C 5 H 2 t Bu 3 ) with CO or the isocyanide CNXyl (Xyl = C 6 H 3 Me 2 -2,6) yields the carbonyl complex Cp ttt 2 Sc(CO), 1 , or the isocyanide complex Cp ttt 2 Sc(CNXyl), 2 , which were identified by X-ray crystallography. Isotopic labeling with 13 CO shows the CO stretch of 1 at 1875 cm -1 shifts to 1838 cm -1 in 1- 13 CO . 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) 45 Sc 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 ttt 2 Sc 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.