Chiral one-dimensional O-P-O bridged Mn-III-Schiff base complexes

Two couples of enantiomerically pure metal phosphonates are successfully synthesized by using chiral Mn-III-Schiff base mononuclear precursors. Compounds [Mn((R,R)-5-Brsalcy)(2-FC6H4PO3H)]center dot 3H(2)O (1) and [Mn((R,R)-5-Brsalcy)(4-CH3C6H4PO3H)]center dot CH3OH center dot H2O (3) [5-Brsalcy = N,N'-(1,2-cyclohexanediylethylene)-bis(5-bromosalicylideneiminato) dianion] are isostructural and show similar one-dimensional chain structures where the Mn((R,R)-5-Brsalcy)(+) species are bridged by O-P-O units. Compounds 2 and 4 are (S,S)-enantiomers of 1 and 3, respectively. These compounds are all optically active, exhibiting second harmonic generation responses 0.3 times that of urea. The magnetic measurements of 1 and 3 reveal that dominant antiferromagnetic interactions are mediated between the Mn-III centers.