Crystal structures of phosphine-supported (η5-cyclo-penta-dien-yl)molybdenum(II) propionyl complexes.

Three cyclo-penta-dienylmolybdenum(II) propionyl complexes featuring tri-aryl-phosphine ligands with different para substituents, namely, dicarbon-yl(η5-cyclo-penta-dien-yl)propion-yl(tri-phenyl-phosphane-κP)molybdenum(II), [Mo(C5H5)(C3H5O)(C18H15P)(CO)2], (1), dicarbon-yl(η5-cyclo-penta-dien-yl)propion-yl[tris-(4-fluoro-phen-yl)phosphane-κP]molybdenum(II), [Mo(C5H5)(C3H5O)(C18H12F3P)(CO)2], (2), and dicarbon-yl(η5-cyclo-penta-dien-yl)propion-yl[tris-(4-meth-oxy-phen-yl)phosphane-κP]molybdenum(II) dichloromethane solvate, [Mo(C5H5)(C3H5O)(C21H21O3P)(CO)2]·CH2Cl2, (3), have been prepared from the corresponding ethyl complexes via phosphine-induced migratory insertion. These complexes exhibit four-legged piano-stool geom-etries with mol-ecular structures quite similar to each other and to related acetyl complexes. The extended structures of the three complexes differ somewhat, with the para substituent of the tri-aryl-phosphine of (2) (fluoro) or (3) (meth-oxy) engaging in non-classical C-H⋯F or C-H⋯O hydrogen-bonding inter-actions. The structure of (3) exhibits modest disorder in the position of one Cl atom of the di-chloro-methane solvent, which was modeled with two sites showing approximately equivalent occupancies [0.532 (15) and 0.478 (15)].