Previous work on uric acid Present workd
  Crystala B3LYPb B3LYPc H2U(vac) H2U(aq) HU-(aq) U2‒(aq)
N1-C2 1.369 1.388 1.386 1.386 1.383 1.410 1.408
C2-N3 1.383 1.403 1.401 1.401 1.389 1.359 1.347
N3-C4 1.360 1.370 1.368 1.368 1.363 1.334 1.358
C4-C5 1.364 1.367 1.364 1.363 1.369 1.387 1.406
C5-C6 1.410 1.433 1.430 1.430 1.423 1.409 1.397
C6-N1 1.401 1.423 1.422 1.422 1.416 1.404 1.408
C5-N7 1.388 1.399e 1.399 1.399 1.398 1.405 1.400
N7-C8 1.361 1.381 1.379 1.379 1.373 1.371 1.396
C8-N9 1.378 1.426 1.424 1.424 1.411 1.395 1.369
N9-C4 1.361 1.370 1.368 1.368 1.363 1.386 1.366
C2-O 1.237   1.212 1.212 1.220 1.245 1.259
C6-O 1.246   1.217 1.217 1.227 1.245 1.258
C8-O 1.252   1.209 1.209 1.221 1.231 1.255
aRingertz [29]
bB3LYP/6-31G(d), Chen et al. [30]
cB3LYP/6-311++G(d,p), Allen et al. [31]
dB3LYP/6-311++G(d,p)
emislabeled as C6-N7
Table 1: Optimized bond lengths (in Ångstroms) of uric acid and its anions.