Solution Synthesis,Structure, and CO2 Reduction Reactivity of a Scandium(II) Complex, {Sc[N(SiMe3)2]3}−

The first crystallographically characterizable complex of Sc²⁺, Sc(NR₂)₃]^? (R=SiMe₃), has been obtained by LnA₃/M reactions (Ln=rare earth metal; A=anionic ligand; M=alkali metal) involving reduction of Sc(NR₂)₃ with K in the presence of 2.2.2‐cryptand (crypt) and 18‐crown‐6 (18‐c‐6) and with Cs in the presence of crypt. Dark maroon K(crypt)]⁺, K(18‐c‐6)]⁺, and Cs(crypt)]⁺ salts of the Sc(NR₂)₃]^? anion are formed, respectively. The formation of this oxidation state of Sc is also indicated by the eight‐line EPR spectra arising from the I =7/2 ⁴⁵Sc nucleus. The Sc(NR₂)₃ reduction differs from Ln(NR₂)₃ reactions (Ln=Y and lanthanides) in that it occurs under N₂ without formation of isolable reduced dinitrogen species. K(18‐c‐6)]Sc(NR₂)₃] reacts with CO₂ to produce an oxalate complex, {K₂(18‐c‐6)₃}{(R₂N)₃Sc]₂(μ‐C₂O₄‐κ ¹O:κ ¹O′′)}, and a CO₂^? radical anion complex, (R₂N)₃Sc(μ‐OCO‐κ ¹O:κ ¹O′)K(18‐c‐6)]_n .