Stabilization of η3-indenyl compounds by sterically demanding N,N-chelating ligands in the molybdenum coordination sphere

A series of eta(3)-indenyl molybdenum compounds [(eta(3)-4,7-Me2C9H5)Mo(CO)(2)(L-N,L-N)Cl] (L-N,L-N = bpy, phen, pyma), isostructural with well-known eta(3)-allyl compounds, was synthesized from the recently established halide synthon [{(eta(5)-4,7-Me2C9H5)Mo(CO)(2)(mu-Cl)}(2)]. The low stability of the hexacoordinated h 3-indenyl molybdenum species in solution has been overcome by a modification of the chelating ligand. Hence, the dissociation of the compounds bearing ligands with methyl groups beside nitrogen donor atoms (e.g. 6,6'-Me-2-bpy, 2,9-Me-2-phen; 2,9-Me-2-4,7-Ph-2-phen) is strongly disfavored due to the steric requirements of the substituents. The considerable discrimination of the pentacoordinated species enables the use of [(eta(5)-4,7-Me2C9H5)Mo(CO)(2)(2,9-Me-2-phen)][BF4] for the assembly of derivatives bearing other halides and pseudohalides in the coordination sphere of molybdenum. The current study further describes some other new indenyl complexes accessible from [{(eta(5)-4,7-Me2C9H5)Mo(CO)(2)(mu-Cl)}(2)]. All structural types presented in this experimental study were supported by X-ray crystallographic data.