Metal Complexes of Trindane: Possible Precursors of Sumanene

Trindane (the condensation trimer of cyclopentanone) yields complexes of the type (η6-trindane)ML n , where ML n = Cr(CO)3 (6), Mo(CO)3 (8), Mn(CO)3 + (9), or (C5H5)Fe+ (10a,10b). X-ray crystallographic data are reported for (η6-trindane)Cr(CO)3 (6) and show that the three five-membered rings adopt envelope conformations in which the central methylene groups are bent toward the metal. When the chromium complex 6 is stirred with DMSO-d 6 in the presence of t-BuOK, up to 12 benzyl protons can be exchanged for deuterons, giving a mixture of partially deuterated products. In contrast, the iron complex 10b undergoes complete H/D exchange at all 12 benzylic sites. The possibility of preparing all-cis hexamethyltrindane as a precursor to sumanene is discussed.