1,1′-Fc(4-C6H4CO2Et)2 and its unusual salt derivative with Z′=5, catena-[Na+]2[1,1′-Fc(4C6H4CO2-)2]•0.6H2O[1,1′-Fc = (η5-(C5H4)2Fe]

The neutral diethyl 4,4'-(ferrocene-1,1'-diyl) dibenzoate, Fe[eta(5)(C5H4)(4-C6H4CO2Et)](2) (I), yields (II) (following base hydrolysis) as the unusual complex salt poly[disodium bis[diethyl 4,4'-(ferrocene-1,1'-diyl) dibenzoate] 0.6-hydrate] or [Na+](2)[Fe{eta(5)-(C5H4)-4-C6H4CO2-}(2)]center dot 0.6(H)2O with Z' = 5. Compound (I) crystallizes in the triclinic system, space group P (1) over bar, with two molecules having similar geometry in the asymmetric unit (Z' = 2). The salt complex (II) crystallizes in the orthorhombic system, space group Pbca, with the asymmetric unit comprising poly[decasodium pentakis[diethyl 4,4'-(ferrocene-1,1'-diyl) dibenzoate] trihydrate] or [Na+](10)[Fe{eta(5)-(C5H4)-4-C6H4CO2-}(2)](5)center dot 3H(2)O. The five independent 1,1'-Fc[(4-C6H4CO2)(-)](2) dianions stack in an offset ladder (stepped) arrangement with the ten benzoates mutually oriented cisoid towards and bonded to a central layer comprising the ten Na+ ions and three water molecules [1,1'-Fc = eta(5)-(C5H4)(2)Fe]. The five dianions differ in the cisoid orientations of their pendant benzoate groups, with four having their -C6H4- groups mutually oriented at interplanar angles from 0.6 (3) to 3.2 (3)degrees (as pi center dot center dot center dot pi stacked C-6 rings) and interacting principally with Na+ ions. The fifth dianion is distorted and opens up to an unprecedented -C6H4- interplanar angle of 18.6 (3)degrees through bending of the two 4-C6H4CO2 groups and with several ionic interactions involving the three water molecules (arranged as one-dimensional zigzag chains in the lattice). Overall packing comprises twodimensional layers of Na+ cations coordinated mainly by the carboxylate O atoms, and one-dimensional water chains. The non-polar Fc(C6H4)(2) groups are arranged perpendicular to the layers and mutually interlock through a series of efficient C H H center dot center dot center dot pi stacking contacts in a herringbone fashion to produce an overall segregation of polar and non-polar entities.