Coordination chemistry of cyclopentadienyl ester-disubstituted Ligands. Synthesis and solid state structures of [Na([18]-crown-6)][C5H3(CO2Et)(2)-1,2] and [Mn{C5H3(CO2Ph)(2)-1,2} (CO)(3)]

The disubstituted alkyl- and aryloxycarbonylcyclopentadienides of sodium Na [C5H3(CO2R)(2)-1,2] [R = Me (3a), Et (3b), Ph (3c)] are obtained in a two-s tep synthesis. The known Na[C5H4(CO2R)] [R = Me (1a), Et (2b)] and the hith erto unknown Na[C5H4(CO2Ph)] (1c), prepared from NaCp and dialkyl- or diphe nyl carbonate, are subsequently reacted with the corresponding chloroformat es ROCOCl to give 3 contamined with variable amounts of 1,3 isomers. Treatm ent of 3b with [18]-crown-6 affords the buff-colored crystalline salt [Na([ 18]-crown-6)] [C5H3(CO2Et)(2)-1,2] (4b). Reactions of 4b and 3c with MBr(CO )(5) [M = Mn, Re] or [RuCl2(CO)(3)](2) lead to the respective metal complex es [M{eta (5)-C5H3(CO2R)(2)-1,2)(CO)(3)] [R = Et and M = Mn (5b) or Re (6b) , R = Ph and M: = Mn (5c)] and [Ru{C5H3(CO2Et)(2)-1,2}(CO)](2) (7b). The so lid state structure of 4b reveals ion pairs in which the anion adopts an id ealized C-2v conformation and chelates the sodium (kappa O-2,O'-coordinatio n), The structure of [Mn(C5H3(CO2Ph)2-1,2)(CO)(3)] (5c) confirms the expect ed eta (5)-coordination of the Cp ring and exhibits significant torsion ang les between the Cp ring and carboxylate groups.