Hydrogen-bonded adducts of ferrocene-1,1′-diylbis(diphenylmethanol): crystal and molecular structures of 1 : 1 adducts with 4,4′-bipyridyl, piperazine and dimethylformamide, the 2 : 1 : 1 hydrated adduct with morpholine, and two adducts with 1,4-dioxane, 1 : 1 at 150 K and 1 : 2 at 298 K

Abstract

Host–guest adducts formed by ferrocene-1,1′-diylbis(diphenylmethanol)1 with oxygen- and/or nitrogen-containing guests exhibited a wide range of hydrogen-bonding patterns as determined by X-ray crystallography. The 1 : 1 adduct 2 formed with 4,4′-bipyridyl comprises a centrosymmetric hydrogen-bonded aggregate involving two molecules of the diol and one of the bipyridyl and contains intramolecular O–H ⋯ O and intermolecular O–H ⋯ N hydrogen bonds; the second molecule of the bipyridyl, also centrosymmetric, is trapped in a cavity, but is not hydrogen bonded to any other part of the structure. The structure of the 1 : 1 adduct formed with piperazine 3 is chiral and consists of infinite spiral chains, with alternating diol and piperazine molecules, which contain only O–H ⋯ N hydrogen bonds. Morpholine forms both anhydrous 4a and hydrated adducts 4b with the host diol, both having host: guest ratios of 2 : 1 : the hydrated adduct contains infinite ribbons comprising ferrocene units on the outside edges and disordered water and morpholine components in the body of the ribbon. With 1,4-dioxane a 1 : 1 5a and a 1 : 2 adduct 5b are formed. The centrosymmetric hydrogen-bonded aggregate of 5a consists of two molecules of the diol and one of dioxane and contains both intra- and inter-molecular O–H ⋯ O hydrogen bonds: the second dioxane molecule is also centrosymmetric and is trapped in a structural cavity and not bonded to the rest of the structure. Adduct 5b is isomorphous with the 1 : 2 diol : pyridine adduct. The diol component lies on a two-fold rotation axis, forming hydrogen bonds to the dioxane molecules which are highly disordered and readily lost from the structure. In the 1 : 1 complex formed with dimethylformamide 6 inter- and intra-molecular O–H ⋯ O hydrogen bonds link a finite host–guest pair, which also includes an intermolecular C–H ⋯π(arene) interaction. The hydrogen-bonding patterns are analysed and codified using a graph-set approach.