A REINVESTIGATION OF THE REACTION OF [FE2(ETA-C5H5)2(CO)4-N(CNR)N] (N = 1 OR 2) WITH STRONG ALKYLATING-AGENTS

The reaction of [Fe2(eta-C5H5)2(CO)3(CNR)] with R'OSO2CF3 (R,R' = Me or Et) gives a mixture of cis and tranS-[Fe2(eta-C5H5)2(CO)2(mu-CO){mu-CN(R')R}]SO3CF3. When R = R' = Me the isomer ratio is variable, but the cis always predominates and is the only product when R not-equal R'. The complexes [Fe2(eta-C5H5)2(CO)2(CNR)2] react with R'OSO2CF3 and the more reactive alkyl halides R'X to give a mixture of cis-[Fe2(eta-C5H5)2(CO)(CNR)(mu-CO)(nu(CN(R')R}]X and cis-[Fe2(eta-C5H5)2(CO)2{mu-CN(R')R}2][X]2. In both series of cations the presence of mu-CN(R')R ligands give rise to isomers that differ in respect of orientation about the C=N bond. The cations are not fluxional and do not undergo cis-trans interconversion, bridge-terminal ligand exchange, or rotation about the mu-C = N(R')R double bond. The structure of the cations in the [Fe2(eta-C5H5)2(CO)(CNMe2)(mu-CO)(mu-CNMe2)]BPh4 and [Fe2(eta-C5H4Me)2(CO)2(mu-CNMe2)2][SO3CF3]2 salts were confirmed as cis by X-ray diffraction studies. Their dimensions are similar to those previously found in cis-[Fe2(eta-C5H4Me)2(CO)2(mu-CO)(mu-CNMe2)]I, but with variations due to the differing acceptor and donor abilities of the various ligands. Infrared and NMR spectra of the complexes are reported and discussed.