A novel, tunable manganese coordination system based on a flexible "spacer" unit: Noncovalent templation effects

The reaction of bis(hexafluoroacetylacetonato)manganese(II) trihydrate (2), an similar to 90 degrees corner unit, with flexible linking unit 4,4'-trim ethylenedipyridine (1) allows for the potential formation of three differen t types of solid-state coordination species: infinite helical polymers, clo sed dimeric systems, and infinite one-dimensional polymers. While the un-te mplated starting material is known to give a coordination helix, the other two possible species can be realized through the selective use of a variety of simple, organic guests: toluene (3), diphenylmethane (4), cis-stilbene (5), 1,3-diphenylpropane (6), benzyl alcohol (7), nitrobenzene (8), and cya nobenzene (9). When solutions of I and 2 are crystallized in the presence o f all of these clathrates, the dimeric macrocycles result in all cases, exc ept for that of 6, in which a syndiotactic, wedge-shaped polymer forms. Emp loying a linker that is less rigid than is typically used in crystal engine ering, such as 1, enables the nucleophilic donor subunit to be more than ju st a simple "spacer", instead making it an essential, tunable component in the overall crystal lattice. In so doing, a great deal of molecular "inform ation" is lost, but this is compensated for by an in-depth investigation in to the weaker host-guest and/or guest-guest interactions, such as nonclassi cal hydrogen bonding and an assortment of hydrophobic interactions, present in the various systems.