HYDROGEN-BONDING OF HYDROXY-GROUPS TO CARBANIONS IN INDENIDE AND FLUORENIDE DERIVATIZED ALCOHOLS DIRECTLY OBSERVED BY UV, IR, AND NMR-SPECTROSCOPY

For investigation of hydrogen bonding to carbanions a number of carban ions containing hydroxy groups have been designed and synthesized. The carbanions were of the type R'-CR2-CHR-CR2-OH, with R' being an inden ide or a fluorenide group and R a methyl group or a hydrogen, and were generated from the corresponding indenes and fluorenes. Intramolecula r hydrogen bonding was observed by UV, IR, and NMR spectroscopy in bot h polar [dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF)] and apol ar (benzene and toluene) non-hydrogen bond donor solvents with properl y designed carbanions. In the latter solvents cryptand 211 was used fo r complexation of the counter Li+ cation. For some derivatives the pre sence of both intramolecular hydrogen bonding to the carbanion and int ermolecular hydrogen bonding of the hydroxy group to the solvent was o bserved. The UV spectroscopy indicated the perturbation of the proton accepting carbanion and IR and NMR spectroscopy showed the effect of t he hydrogen bonding on the proton donating OH group.