Metal Complexes of Trindane:  Possible Precursors of Sumanene

Trindane (the condensation trimer of cyclopentanone) yields complexes of the type (η 6 -trindane)ML n, where ML n = Cr(CO) 3 ( 6 ), Mo(CO) 3 ( 8 ), Mn(CO) 3 + ( 9 ), or (C 5 H 5 )Fe + ( 10a, 10b ). X-ray crystallographic data are reported for (η 6 -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.