(η 5 -Carb-oxy-cyclo-penta-dien-yl)(η 7 -cyclo-hepta-trien-yl)manganese(I) hexa-fluorido-phosphate.

The title compound, [Mn(C 7 H 7 )(C 6 H 5 O 2 )]PF 6 or [(Cht)Mn(Cp'CO 2 H)]PF 6 , with Cht = cyclo-hepta-trienyl and Cp' = C 5 H 4 , is an air-stable, purple, heteroleptic, cationic sandwich complex with manganese in oxidation state +I and π-coordinating cyclo-hepta-trienyl and cyclo-penta-dienyl ligands. The latter ligand carries the carb-oxy-lic acid functionality. This 'tromancenium-8-carb-oxy-lic acid' with hexa-fluorido-phosphate as counter-ion represents a rare case of a cationic carb-oxy-lic acid. Structurally, this organometallic carb-oxy-lic acid displays the common motif of planar O sp 2 ⋯H-O sp 3 /O sp 3 -H⋯O sp 2 hydrogen-bonded carb-oxy-lic acid dimers with anti -oriented metallocenyl moieties, the cationic charge of which is balanced by octa-hedrally shaped hexa-fluorido-phosphate anions. Positional disorder is observed in the cyclo-hepta-trienyl ring and the PF 6 - anion.