ONE-ELECTRON VS 2-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 N2O gave two different products depending o n 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(O RPG)(THF)(2)][Li(THF)(4)] (3) where only one electron was transferred to N2O. The structures of 1b, 2a, and 3a have been elucidated by X-ray crystal structures. Crystal data are as follows. 1b: C60H96O4CrN4Li2, monoclinic P2(1)/c, a = 20.504(2) Angstrom, b = 12.347(1) Angstrom, c = 22.524(1) Angstrom, beta = 94.56(1)degrees, Z = 4. 2a: C48H72O4CrN4 Li2, monoclinic P2(1)/n, a = 11.687(1) Angstrom, b = 20.273(3) Angstro m, c = 19.467(3) Angstrom, beta = 100.27(1)degrees, Z = 4. 3a: C60H96O 6CrN4Li, monoclinic P2(1)/c, a = 13.884(1) Angstrom, b = 16.170(1) Ang strom, c = 25.514(2) Angstrom, beta = 90.59(1)degrees, Z = 4.