Table 5. Infrared Stretching Frequencies (cm^–1) of the Terminal (ν^t_CO) and Bridging (ν^b_CO) Carbonyl Groups for 3^n– in CH₃CN as a Function of Cluster Charge n.

cluster charge n	νtCO	νbCO
–4	2013	1870
–5	2002	1860
–6	1987	1846
–7	1972	1832
–8	1957	1818