Self assembled polynuclear [3 x 3] grids -: structural and magnetic properties of Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) complexes with Mn9(μ2-O)12 cores

A series of polynuclear [3 x 3] square grid complexes of Mn(II), Fe(III), Co(II), NI(II), and Cu(II) is reported from the high yield self assembly reactions of the linear tritopic ligands H(2)L3 and H(2)L4 and appropriate metal salts. Structural data reveal a complementary matching of the ligand coordination pockets and the coordination requirements of the metal ions in the [3 x 3] square alkoxide bridged grids found in [Mn-9(L3)(6)](ClO4)(6). 18H(2)O, [Mn-9(L4)(6)](NO3)(6). 12H(2)O and [Cu-9(HL3)(6)](NO3)(12). 9H(2)O. Similar structural types are implicated for analogous Ni(II), Co(II), and Fe(III) complexes. The structural and magnetic properties are discussed. The Cu-9 grid system exhibits both intramolecular ferromagnetic and antiferromagnetic coupling, and has an S = 7/2 ground state. A similar situation appears to exist for the analogous Fe(III), complex, with a spin ground state approaching S = 29/2. The Mn(II)(9), Ni(II)(9) and Co(II)(9) complexes exhibit intramolecular antiferromagnetic coupling. (C) 2001 Elsevier Science Ltd. All rights reserved.