Coordination of 4,7-bis(2-hydroxybenzyl)-1-oxa-4,7-diazacyclononane (LH2) with manganese(II) and -(III) and zinc(II). Crystal structure of [(LH)2Zn2(.mu.-OH)](PF6).cntdot.0.5CH3OH

The pentadentate macrocyclic ligand 4,7-bis(2-hydroxybenzyl)-1-oxa-4,7-diazacyclononane (LH2) has been prepared for the first time, and its coordination chemistry with manganese(II) and -(III) and zinc(II) has been investigated. From methanolic solutions of LH2, Mn(ClO4)2.6H2O, and Zn(ClO4)2.6H2O, colorless crystals of [(LH)2Mn2(mu-OH)](ClO4) and [(LH)2Zn2(mu-OH)]-(ClO4).7H2O have been obtained, respectively. The crystal structure of [(LH)2Zn2(mu-OH)](PF6).0.5CH3OH has been determined by X-ray crystallography. Crystal data: orthorhombic space group Pncb, a = 12.254 (5) angstrom, b = 18.066 (8) angstrom, c = 19.605 (9) angstrom, Z = 4. Two octahedrally coordinated zinc ions are connected by a mu-hydroxo bridge. The coordinated phenolate and phenolic groups of both LH- ligands form two intramolecular O-H...O contacts. From temperature-dependent magnetic susceptibility measurements and EPR spectroscopy on [(LH)2Mn2(mu-OH)][B(C6H5)4] an intramolecular antiferromagnetic exchange coupling constant, J, of -2.65 cm-1 has been determined (H(ex) = -2JS1.S2; S1 = S2 = 5/2; g = 2.0). Deprotonation of the dinuclear Mn(II) species by N(C2H5)3 in CH3CN affords monomeric five-coordinate LMn(II). LMn(III)X complexes (X = Cl, NCS, N3) have also been prepared, as well as [LZn(H2O)ZnCl2].