A comparison between the structures of [Mn-III(bbpen)] [PF6] and [Mn-III(bbppn)][PF6] (H(2)bbpen=N,N'-bis(2-hydroxybenzyl)-N,N'-(2-pyridylmethyl)ethylenediamine, H(2)bbppn=N,N'-bis(2-hydroxybenzyl)-N,N'-(2-pyridylmethyl)-1,3-propanediamine)

The reaction of Mn(OAc) . 2H(2)O in methanolic solution with N,N'-bis(2-hydroxybenzyl)-N,N'-(2-pyridylmethyl)-1,3-propanediamine (H(2)bbppn; C29H32N4O2) affords upon addition of NH4PF6 green crystals of the monomeric [Mn-III(bbppn)] [PF6] (2) complex. The crystal structure of 2 has been determined by X-ray crystallography. Crystal data: monoclinic P2(1)/n (No. 14), a=12.762(1), b=12.543(2), c = 19.008(2) Angstrom, beta=93.18(2)degrees, V = 3038(1) Angstrom(3), Z=4. The structure has been refined to an R factor of 6.5% based on 2322 observed reflections. The arrangement of bbppn(2-) around the Mn-III center in 2 is compared to the close related [Mn-III(bbpen)] [PF6] (1) complex (H(2)bbpen = N,N'-bis(2-hydroxybenzyl)-N,N'-(2-pyridylmethyl)ethylenediamine). The fundamental geometric difference between the two structures lies in the isomeric nature of the coordination of the N4O2-donor set, which results in quite different bond distances around the metal centers.