Infrared studies of halide binding with CpMn(CO)2X complexes where X = ligands bearing the O–H or N–H group

Abstract Halide ion binding to the OH group of CpMn(CO) 2 (3-hydroxypyridine) complex has been investigated using infrared absorption spectroscopy via the ν CO bands. Fluoride ion interaction in chloroform causes the largest redshift of up to 12 cm −1 . The infrared bands of CpMn(CO) 2 L complexes containing N–H groups are redshifted to a similar extent. The displacement of the 3-hydroxypyridine ligand from the manganese complex by PPh 3 is prevented because of a Mn–N bond strengthening effect induced by OH⋯F − binding. Density functional calculations also lend support to the large effect that OH⋯F − interaction has on the magnitude of the ν CO redshift and Mn–N bond energy of CpMn(CO) 2 (3-hydroxypyridine).