CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF A NEW OXO-CENTERED BASICBENZOIC BRIDGING MIXED-VALENCE TRINUCLEAR COMPLEX MN(III)CO(III)MN(II)O(PHCOO)(6)PY(3)

A new mixed-valence heterotrinuclear complex [Mn-III Co-III (MnO)-O-II (PhCOO)(6)Py(3)] was first synthesized by using NBu(4)MnO(4) as the ox idizer. In the reaction, Co-II ions were oxidized to Co-III, while Mn- VII were reduced to Mn-II and Mn-III. The oxidation number of three me tal ions were +3, +3 and +2, which was proved by the electrical conduc tivity. There are two types of trinuclear species in the single cell. One is valence delocalized in which the bond distance Co(2)-O(2) is 1. 85(2) Angstrom and the distance M-O is 1.933(9) Angstrom, which is an average value of Mn-II-O and Mn-III-O; another is valence-localized in which the bond distance of Co-III-O is 1.84(1), Mn-III-O, 1.86(1), Mn -II-O, 1.99(1) Angstrom. Variable temperature (1.5-300 K) magnetic sus ceptibility indicated that there is antiferromagnetic exchange interac tion among the three metal ions. Copyright (C) 1997 Elsevier Science L td.