One Dimensional Iron Molybdophosphate Anionic Chains with Different Structural Arrangements Reflecting a Flexibility Character

Structural comparison of a new compound [（bpp）3H6]Fe2ⅢFe2ⅡMo24Ⅴ（H2PO4）8（HPO4）4（PO4）4O48（OH）12·（H2O）4·2H2O（1）[bpp=1,3-di（4-pyridyl）propane] with our previously reported two compounds [（bpy）3FeⅡ]3·Fe2ⅢFe2ⅡMo24Ⅴ（H2PO4）8（HPO4）4（PO4）4O48（OH）12（H2O）4·12H2O（2） and [（bpy）3FeⅡ]2FeⅡFeⅢMo12Ⅴ（H2PO4）2（H2-xPO4）.（H1＋xPO4）（HPO4）2（PO4）2O24（OH）6（H2O）2·9H2O（x=0-1）（3）（bpy=2,2＇-bipyridine）,which all exhibit one-dimensional mixed-valence iron molybdophosphate anionic chains constructed by alternating connection of FeⅢ ions and magic [FeⅡ（Mo6P4O31）2] units,reveals that the non-hydrogen atomic ratios of Mo∶Fe∶P∶O within the polymeric anionic chains are the same for all the three compounds,while the polymeric anionic chains of the different compounds bear different numbers of negative charges.And therefore there exist different numbers of counter cations per {Fe2Ⅲ[Fe2Ⅱ（P16Mo24ⅤO124）]} unit found in the titled compounds.It discloses that not only are the spatial assembling of counter cations and polymeric inorganic chains of three compounds quite different,but also the O-FeⅢ-O bond angles and FeⅢ-O bond lengths of the three different inorganic chains exhibit small differences.What is more important is that such small changes in bond length and bond angle in the assemblage of FeⅢ-O bonds lead to the considerable fluctuations of inorganic chains in their structural conformation within the three compounds,reflecting an interesting phenomenon of＂flexibility＂ in the pure inorganic one dimensional mixed-valence iron molybdophosphate chains.