Comparison of Photoacoustic, Attenuated Total Reflection, and Transmission Infrared Spectra of Crystalline Organoiron(II) Carbonyl Complexes

Abstract

Photoacoustic (PA), attenuated total reflection (ATR), and transmission IR spectra of the solid organoiron(II) complexes, CpFe(CO)2I and [ CpFe(CO)2 R]BF4 ( Cp = η5-C5H5; R = C2H4, CH2CMe2, 3-Me-thiophene), have been recorded at room temperature in the near-, mid-, and far-IR regions. Vibrational assignments are proposed for most of the observed bands including those in the binary overtone and combination regions. The relative intensities of the peaks in the different spectral regions indicate that PAS is the most sensitive in the near-IR region, affording good information on binary vCO and vCH overtones and combinations, while ATR spectroscopy leads to the most intense peaks in the far-IR region.