OLIGONUCLEAR ORGANOMETALLIC COMPLEXES WITH BORON-NITROGEN BRIDGES

The facile formation of boron-nitrogen bridges allows the one-step ass embly of oligonuclear organometallic complexes. By the; reaction of 1- (dibromoboryl)ferrocene (1a) and 1,1'-bis(dibromoboryl)ferrocene (1b) with 1-[(dimethylamino)methyl]ferrocene (2) and (eta 6-aniline)tricarb onylchromium derivatives (3, 4) dinuclear to pentanuclear units (5-10) were obtained. The homodimetallic compound FcBBr(2)- NMe(2)CH(2)Fc (5 , Fc: ferrocene) closely resembles a propylene-bridged complex. Its da tive B-N link is stable at temperatures as high as 100 degrees C. Each of the heterooligonuclear aggregates 7-10 is tied together by covalen t B-N bonds, which are isoelectronic with ethylene bridges. In FcB(Br) -N(Me)Bct [7, Bct: (eta(6)-C6H5)Cr(CO3)] and 1,1'-Fc[B(Br)-N(Me)Bct](2 ) (9) B-N pi bonding dominates over the N-Bct pi interaction as indica ted by spectroscopical data and an X-ray analysis of 9. The N-lithiate d compounds BctNRLi (4a, b; R = H, Me) possess a remarkably increased N-Bct pi donation compared to the protonated parent compounds, which r esults in a further perturbation of the local C-3v symmetry of the (C6 H5)Cr(CO3) framework.