Crystal engineering of chiral superstructures based on (R)-(+)-1,1 '-bi-2-naphthol and the alkali derivatives of racemic (R,S)-1,1 '-bi-2-naphthol

(R)-(+)-1,1'-Bi-2-naphthol [(R)-(+)-(HOC10H6C10H6OH)] has been used as a ch iral building block in the construction of chiral organo-organometallic cry stals. The reaction of the neutral molecule with [Co(eta (5)-C5H5)(2)] in d iethyl ether yields the supramolecular salts [Co-III(eta (5)-C5H5)(2)][(R)- (+)-(HOC10H6C10H6O)].[(R)-(+)-(HOC10H6- C10H6OH)] (1) and [Co-III(eta (5)-C 5H5)(2)][(R)-(+)-(HOC10H6C10H6O)].[(R)-(+)-(HOC10H6C10H6OH)](0.5) (2), depe nding on the stoichiometric ratios between the binaphthol and the organomet allic sandwich compound. Molecular aggregation is achieved via a combinatio n of neutral and charge-assisted O-H . . .O bonds between the binaphthol an d binaphtholate components and via weaker interactions of the C-H . . .O an d C-H . . . pi types involving the [Co-III(eta (5)-C5H5)(2)](+) cation. The same reaction with racemic 1,1'-bi-2-naphthol in diethyl ether, followed b y recrystallisation from nitromethane, yields the solvate species [Co-III(e ta (5)-C5H5)(2)]- [(R,S)-(HOC10H6C10H6O)].[(R,S)-(HOC10H6C10H6OH)][MeNO2](1 .5) (3). For comparison, the alkali salts Cs[(R,S)-(HOC10H6C10H6O)].[(R,S)- (HOC10H6C10H6OH)] (4) and Rb[(R,S)-(HOC10H6C10H6O)]. [(R,S)-(HOC10H6C10H6OH )] (5) have also been prepared by treating [(R,S)-(HOC10H6C10H6OH)] with th e Cs and Rb hydroxides. Both organometallic and alkali salts show how the c ations tend to be encapsulated within a niche formed by the folding of hydr ogen-bonded naphthol-naphtholate chains.