Time-resolved IR spectroscopy has been used to characterize vibrational and rotational relaxation dynamics of the C-N stretching bands for aqueous molecular cyanides, Au(CN)(2)(-), Ni(CN)(4)(2-), Pt(CN)(4)(2-), Co(CN)(6)(3-), Mn(CN)(6)(3-), and Ru(CN)(6)(4-). The spectra and dynamics of Ru(CN)(6)(4-) resemble those previously reported for ferrocyanide with a relatively short (<10 ps) vibrational energy relaxation (VER) time. VER times are longer (>30 ps) for Au(CN)(2)(-), Ni(CN)(4)(2-), Pt(CN)(4)(2-) and Co(CN)(6)(3-). Mn(CN)(6)(3-) is an intermediate case with a VER time of 15 ps in water. These VER dynamics extend and reinforce the trends for metal cyanide CN vibrational band frequencies and intensities. (C) 2010 Elsevier B. V. All rights reserved.