An orthorhombic polymorph of isavuconazole

The title compound C₂₂H₁₇F₂N₅OS (systematic name: 4-{2-[(2<i>R</i>,3<i>R</i>)-3-(2,5-di-fluoro-phen-yl)-3-hy-droxy-4-(1,2,4-triazol-1-yl)butan-2-yl]-1,3-thia-zol-4-yl}benzo-nitrile), represents a new ortho-rhom-bic polymorph of isavuconazole. The two stereogenic centers adopt the <i>R</i>,<i>R</i> configuration. In the crystal structure of the ortho-rhom-bic form, a mono-periodic chain motif is formed by a strong O-H⋯N hydrogen bond, while three additional C-H⋯N inter-actions propagate these chains into a tri-periodic supra-molecular network. A comparison with the previously reported monoclinic polymorph [Voronin <i>et al.</i> (2021 ▸). <i>CrystEngComm</i> <b>23</b>, 8513] is provided, supported by Hirshfeld surface and energy framework analyses.