A NEW OXO-CENTRED, MIXED-VALENCE HETEROTRINUCLEAR COMPLEX, Mn(III)Ni(III)Mn(II)O(PhCOO)₆Py₃ CRYSTAL STRUCTURE AND MAGNETIC PROPERTIES

Abstract

A new mixed-valence heterotrinuclear complex, Mn(III)Ni(III)Mn(II)O(PhCOO)₆Py₃, was synthesized using NBu₄MnO₄ as an oxididant. In the reaction, Ni(II) was oxidized to Ni(III) while Mn(VII) was reduced to Mn(II) and Mn(III). Crystals are monoclinic, space group C2/C, with a = 58.93(4). 6=11.784(3), c = 24.883(9) Å, β=100.64(4)°, V= 16983(13) Å,³and Dc = 1.35 gem⁻³ for Z = 12. The crystal structure was solved by direct methods to final R = 0.083, Rω− 0.095. There are two kinds of trinuclear species in the unit cell. One is valence delocalized with Ni(2)—O(2) 1.86(2) Å and Mn-O(2) 1.92(1) Å (average value of Mn(II)—O and Mn(III)—O). The other is valence localized with Ni(III)—O(1) 1.84(1) Å, Mn(III)—O(l) 1.88(1) Å and Mn(II)—O(1) 1.97(1) Å. Variable temperature (1.5–300K) magnetic susceptibilities indicated an antiferromagnetic exchange interaction among the three metal ions.

Key Words:

• Heterotrinuclear
• mixed-valency
• Nickel(III)
• X-ray structure
• magnetic properties