Polynuclear manganese amino acid complexes

The reaction of MnCl2 center dot 4H(2)O with DL-valine (Val) in MeOH in the presence of Et-saoH(2) (2-hydroxypropiophenone oxime) and NEt4OH forms the complex [(Mn3Mn2O2)-Mn-III-O-IV-(CH3O)(Et-sao)(6)(Val)]center dot Val center dot 1.5H(2)O (1 center dot Val center dot 1.5H(2)O) in very good yields. A similar reaction of MnCl2 center dot 4H(2)O with Glycine (Gly) in MeOH in the presence of saoH(2) (salicylaldoxime) and Ca(OH)(2) yields the complex [(Mn3O)-O-III(sao)(3)(Gly)Cl(MeOH)(3)]center dot 1.87 MeOH center dot 0.13H(2)O (2.1.87 MeOH center dot 0.13H(2)O). Replacing saoH(2) with Me-saoH(2) (2-hydroxyethanone oxime) and Gly with HPABA (para-aminobenzoic acid) in the presence of CH3ONa in MeOH forms the complex [Mn6O2(PABA)(2)(Me-sao)(6)(MeOH)(4)(H2O)(2)]center dot 2[Mn6O2(PABA)(2)(Me-sao)(6)(MeOH)(2)]center dot 11 MeOH (3.11 MeOH) in moderate yields. Magnetic studies for 1 and 2 reveal the presence of both ferromagnetic and antiferromagnetic interactions, leading to S = 2 ground states for both complexes. Complexes 1 and 2 represent the first examples of polynuclear manganese complexes with any naturally occurring alpha-amino acid, while 3 is the first structurally characterised example of a manganese para-aminobenzoate complex.