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 45 Sc 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 }{[(R2 N)3 Sc]2 (µ-C2 O4 -κ1 O:κ1 O'')}, and a CO2- radical anion complex, [(R2 N)3 Sc(µ-OCO-κ1 O:κ1 O')K(18-c-6)]n .