The far infra-red absorption spectra of a series of chemically synthesised, atomically precise phosphine-stabilised gold cluster compounds have been recorded using synchrotron light for the first time. Far-IR spectra of the Au6(Ph2P(CH2)3PPh2) 4(NO3)2, Au8(PPh3) 8(NO3)2, Au9(PPh3) 8(NO3)3, and Pd(PPh3)Au 6(PPh3)6(NO3)2 clusters reveal a complex series of peaks between 80 and 475 cm-1, for which all significant peaks can be unambiguously assigned by comparison with Density Functional Theory (DFT) geometry optimisations and frequency calculation. Strong absorptions in all spectra near 420 cm-1 are assigned to the P-Ph3 stretching vibrations. Distinct peaks within the spectrum of each specific cluster are assigned to the cluster core vibrations: 80.4 and 84.1 cm-1 (Au6) 165.1 and 166.4 cm-1 (Au 8), 170.1 and 185.2 cm-1 (Au9), and 158.9, 195.2, and 206.7 cm-1 (Au6Pd). The positions of these peaks are similar to those observed to occur for the neutral Au7 cluster in the gas phase (Science, 2008, 321, 674-676). Au-P stretching vibrations only occur for Au6 near 420 cm-1, although they appear near 180 cm-1 for Au6Pd and involve gold core vibrations.