One- vs Two-Electron Reduction of N2O Promoted by a Divalent Chromium Macrocyclic Complex

Reaction of [Cr(ORPG)Li 2 (THF) 4 ] ( 1 ) [ORPG = octaalkylporphyrinogen R = Et ( a ), n -Pr ( b )] with N 2 O gave two different products depending on the solvent employed. While a deoxygenation reaction was observed in toluene with formation of the Cr(IV) complex [(THF)(ORPG)Cr(O)(LiTHF) 2 ] ( 2 ), reactions carried out in THF yielded a Cr(III) species [Cr(ORPG)(THF) 2 ][Li(THF) 4 ] ( 3 ) where only one electron was transferred to N 2 O. The structures of 1b, 2a, and 3a have been elucidated by X-ray crystal structures. Crystal data are as follows. 1b: C 60 H 96 O 4 CrN 4 Li 2, monoclinic P 2 1 / c, a = 20.504(2) Å, b = 12.347(1) Å, c = 22.524(1) Å, β = 94.56(1)°, Z = 4. 2a: C 48 H 72 O 4 CrN 4 Li 2, monoclinic P 2 1 / n, a = 11.687(1) Å, b = 20.273(3) Å, c = 19.467(3) Å, β = 100.27(1)°, Z = 4. 3a: C 60 H 96 O 6 CrN 4 Li, monoclinic P 2 1 / c, a = 13.884(1) Å, b = 16.170(1) Å, c = 25.514(2) Å, β = 90.59(1)°, Z = 4.