Axial and equatorial carbene ligands of dimanganese and dirhenium monocarbene complexes: Synthesis, characterisation and structural studies

Abstract

The binuclear alkoxycarbene complexes [M 2(CO) 9{C(OEt)C 4H 3Y}] (M = Mn, Y = S( 1), O( 2); Re, Y = S( 3), O( 4)) were synthesised and characterised, giving axial carbene ligands for the dimanganese complexes, and equatorial carbene ligands for the dirhenium complexes. Aminolysis of these complexes with ammonia and n-propylamine yielded complexes [M 2(CO) 9{C(NHR)C 4H 3Y}] (R = H, M = Mn, Y = S( 5), O( 6); Re, Y = S( 7), O( 8); R = propyl, M = Mn, Y = S( 9), O( 10); Re, Y = S( 11), O( 12)). For the smaller NH 2-substituted carbene ligands, the X-ray structures determined showed equatorial carbene ligands for both dimanganese and dirhenium complexes, while the NHPr-substituted carbene complexes retained the original configurations of the precursor alkoxy carbene complex, indicating that the steric effects of both the M(CO) 5-fragment and the carbene ligand substituent can affect the coordination site of the carbene ligands of Group VII transition metal complexes in the solid state.