SYNTHESES AND CHARACTERIZATION OF 3 STRUCTURE TYPES FOR MANGANESE(III) COMPLEXES WITH N,N'-ETHYLENEBIS(1-PHENYL-3-IMINO-1-BUTANONE)

Three manganese(III) complexes with the ligand bzacen(2-) [bzacen(2-) = N,N'-ethylenebis (1-phenyl-3-imino-1-butanonato)], Mn(bzacen) (pyrid ine)(NCS) (1), [Mn-2(bzacen)(2) (Me OH)(2)](ClO4)(2) (2) and MnCl(bzac en) (3), have been synthesized and characterized by IR, Raman, electro nic spectra and cyclic voltammetry. A structure determination of compl exes 1 and 2 reveals a octahedral coordination with an N2O2 equatorial plane composed of atoms from the Schiff base ligand, while the Mn ato m in complex 3 has square pyramidal coordination. The two MnN2O4 octah edra in complex 2 are joined by sharing two ketone oxygen atoms (Mn-O 1.910 and 2.493 Angstrom) to form a dinuclear [Mn-2(bzacen)(2)(MeoH)(2 )](2+) cation, the Mn,OZ core having an Mn Mn separation of 3.397 Angs trom and Mn-O-Mn angles of 99.7 degrees. In these three complexes v(C= O) and v(C=C) are shifted to lower frequencies in IR and Raman spectra ; pi-pi* transitions, d-pi* charge-transfer transitions and d-d* ligan d field transitions are observed in electronic spectra.