Transition metal (Mn, Co) and zinc formamidinate compounds having the basic beryllium acetate structure, and unique isomeric iron compounds
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abstract
Oxidation of Co2(DPhF)3 or hydrolysis of Co2(DPhF)4 (DPhF=N,N-diphenylformamidinate) gives Co4O(DPhF)6 (I). This tetranuclear compound consists of an oxygen atom centered in a tetrahedron of four-coordinate Co atoms with a DPhF bridge along each edge of the tetrahedron. An idealized Td symmetry is also found for zinc, II, and manganese, III, analogs. The latter, Mn4O(DPhF)6, crystallizes in a disordered fashion so as to appear as two interpenetrating tetrahedra. Two 4-O tetrairon compounds, namely, Fe4O(DPhF)6 (IV) and Fe4O(DBiPhF)6 (V) (DBiPhF=N,N-bisbiphenylformamidinate) are also described. These molecules are isomers of the Co, Zn and Mn molecules in that they have the 'tetrahedron' of metal atoms badly distorted by a different distribution of the formamidinate ligands. Two opposite Fe-Fe edges are doubly bridged, another two opposite edges are singly bridged and the remaining two edges are unbridged. The lengths of these three pairs of opposite edges are shorti medium and long and the idealized molecular symmetry is only C2. Crystal data for Itoluene at -60C are: triclinic, space group P1, a=13.426(3), b=13.491(3), c=22.600(5) , =99.55(3), =95.39(3), =111.80(3), Z=2. For II1.45C6H14 at -60C: orthorhombic, space group Pbca, a=23.8113(8), b=23.406(2), c=30.956(1) , Z=8. For III at - 150C: trigonal, space group R3, a=23.440(1), c=10.708(1) , Z=3. For IV1.5 toluene at -60C: triclinic, space group P1, a=14.920(3), b=15.539(3), c=19.027(4) , =84.63(3), =85.67(3), =63.30(3), Z=2. 1997 Elsevier Science S.A.
