The reaction of methylendicyclopentadiene (bcpmH2) with (CH3CN)3M(CO)3 (M = Cr, Mo, W) gives the complexes bcpmM2(CO)6 (1-3) in good yields (47-78%). The synthesis of bCPmMO2(CO)6Cl2 (4) starts from bcpmLi2 and Mo(CO)6. In a one-pot procedure, acidification with CH3CO2H and reaction with CCl4 give 4 in 43% yield. Low temperature H-1 NMR investigations of 1 and 2 reveal a dynamic process analogous to that already observed for the silylbridged homologues. The X-ray analysis of 1 proves the chiral structure of the molecule, which is the consequence of the distortion of the bcpm-ligand. The Cr-Cr distance is 3.211(2) angstrom.