Attempts to record the room-temperature, FT-IR photoacoustic (PA) spectra of the crystalline group VIB metal chalcocarbonyls, M(CO)6 (M = Cr, Mo, W) and Cr(CO)5(CS), suprisingly failed owing to the high volatilities of the solid complexes in the PA cell, and excellent-quality gas-phase spectra were obtained instead. Vibrational assignments are proposed for these gases for the CO stretching and MCO bending fundamentals, and the associated binary overtone and combination spectra in the 4500-500 cm−1 region. The binary overtone and combination spectra are easily observed in the FT-IR/PA spectra and are useful in distinguishing between the four metal chalcocarbonyl complexes.
Zhen H. Xu, Ian S. Butler, and Francois G. T. St.-Germain, "FT-IR Photoacoustic Spectra of Gaseous Group VIB Metal Chalcocarbonyl Complexes," Appl. Spectrosc. 40, 1004-1009 (1986)