Figure compares the experimental CIVP spectrum of (G) 2 (A) 0 (SA) 1 with the four lowest energy calculated spectra. The higher energy region of the spectrum once again includes the free OH S , free OH G , and the free N-H 2 anti-symmetric and symmetric stretches of G. D 2 tagging (shown in Figure ) establishes that the small peak at 3480 cm -1 in Figure is due to the N 2 tag's effect on the free OH G stretch. The carbonyl C=O stretch region appears as doublet at 1746 and 1766 cm -1 , suggesting that the two carbonyls are likely in slightly different hydrogen bonding environments. In the fingerprint region, we observe distinct bisulfate modes, including the S-OH stretch and SO 3 stretches. However, deducing the origin of the other peaks in this region proves to be challenging. Therefore, we turn to inspect the calculated spectra and structures. The (G) 1 (A) 2 (SA) 2 cluster