The conjugate acid of bis4'-(4-pyridyl)-2,2': 6',2''-terpyridine iron(II) as a self-complementary hydrogen-bonded building block

The protonation of [Fe(1) 2](2+), where 1 = 4`-(4-pyridyl)-2,2`: 6`,2``-terpyridine, generates a trication which forms a one-dimensional, hydrogen-bonded polymer. The single crystal structures of [Fe(1)(H1)][Fe(NCS)(6)]center dot 2H(2)O, [Fe(1)(H1)][Fe(NCS)(6)]center dot MeCN and [Fe(1)(H1)][ClO4] 3 center dot EtOH are reported and illustrate that the packing of the [Fe(1)(H1)](3+) (n) chains in the solid state can be modulated by changing the steric demands of the counter-ion. Subtle changes in packing on going from [Fe(1)(H1)][Fe(NCS) (6)]center dot 2H(2)O to [Fe(1)(H1)][Fe(NCS)(6)]center dot MeCN result in a reorientation of the pendant pyridine rings with respect to the central pyridine ring of the tpy unit in [Fe(1)(H1)](3+).