On the Reaction of [(CO) 3 Fe(μ‐Me 2 NCO) 2 Fe(CO) 2 (NHMe 2 )] with Chelating Ligands — X‐Ray Structures of New Binuclear μ‐Carbamoyl Complexes

Reaction of the binuclear μ‐carbamoyl complex [(CO) 3 Fe(μ‐Me 2 NCO) 2 Fe(CO) 2 (HNMe 2 )] ( 1 ) in toluene with the chelating ligands Ph 2 PCH 2 PPh 2 (dppm) and Ph 2 PCH 2 CH 2 PPh 2 (dppe) gives different results. With dppm only the complex [(CO) 3 Fe(μ‐Me 2 NCO) 2 Fe(CO) 2 (dppm)] ( 3 ) with a dangling ligand is obtained under replacement of amine, whereas with dppe depending on the reaction conditions up to three compounds are found. A 1 : 1 mixture of the educts generates the related complex [(CO) 3 Fe(μ‐Me 2 NCO) 2 Fe(CO) 2 (dppe)] ( 4 ) together with the tetranuclear complex [{(CO) 3 Fe(μ‐Me 2 NCO) 2 Fe(CO) 2 } 2 (dppe)] (5 ). 4 slowly converts into [(CO) 3 Fe(μ‐Me 2 NCO) 2 Fe(CO)(dppe)] ( 6 ) with dppe acting as a chelating ligand. 6 is the first compound in this series in which one of the five CO groups is replaced by another donor. A 2 : 1 molar ratio of 1 and dppe quantitatively produces 5 . Addition of CO to a solution of 6 proceeds under slow reversible conversion of the complex into 4 . The compounds were characterized by the usual spectroscopic methods; 3 , 5 and 6 were also studied by X‐ray diffraction analyses.