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

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) A, β=100.64(4)°, V= 16983(13) A,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) A and Mn-O(2) 1.92(1) A (average value of Mn(II)—O and Mn(III)—O). The other is valence localized with Ni(III)—O(1) 1.84(1) A, Mn(III)—O(l) 1.88(1) A and Mn(II)—O(1) 1.97(1) A. Variable temperature (1.5–300K) magnetic susceptibilities indicated an antiferromagnetic exchange interaction among the three metal ions.