COMPLEXATION OF 1,3-DIHYDRO-1,3-DIBORAPENTAFULVENE DERIVATIVES WITH FE(CO)3 FRAGMENTS - SYNTHESES, CRYSTAL AND ELECTRONIC-STRUCTURE OF MU-(ETA-4-ETA-5-1,3-DIHYDRO-1,3-DIBORAPENTAFULVENE)-BIS(TRICARBONYLIRON) COMPLEXES

Reactions of the 1,3-diborapentafulvene derivatives 1a-c with (CO)3Fe(C8H14)2 lead to the violet dinuclear complexes 3a-c, which possess a slipped triple-decker structure. The X-ray structure analyses of 3b,c reveal that one Fe(CO)3 group is pentahapto-coordinated to the 1,3-diborole frame of C2B2C = C, whereas the other interacts with the Y-shaped B2C = C unit. The latter resembles the interaction of Fe(CO)3 with trimethylenemethane. An MO calculation indicates that the formation of 3 occurs by distortion of 1.Fe(CO)3; the slippage of Fe(CO)3 from eta-5 to eta-4 bonding is followed by eta-5 coordination of the second Fe(CO)3 group.