We have investigated the coordination modes of NNS Schiff base, thioether ligands to manganese (I) carbonyls. The ligands contain ortho substituted pyridines (H, CH 3 , OCH 3 , fluorophenyl) and varying substituents (H, CH 3 ) at the Schiff base linkage. In general, reaction of [Mn(CO) 5 Br] with a tridentate NNS ligand in CH 2 Cl 2 affords species in which the thioether-S may be bound or unbound to the manganese center, depending on the steric and electronic substitution in the ligand framework; as a result, the complexes exhibit two or three carbonyl ligands, respectively. Aldehyde-derived ligand frames ( tricarbonyl motif. We highlight that coordination of these NNS ligands to Mn(I) carbonyls occurs on a soft conformational landscape, and that ligand substituents can be rationally employed to favor the desired coordination mode.

We report the syntheses and characterization of dicarbonyliron complexes derived from tridentate, ortho-substituted Schiff base pyridine/thioether ligands ( R NNS). Metalation reactions of R NNS (R = CH 3 , OCH 3 ) at low temperature (-78°C) with [Fe(CO)