Table 2. Conformation of febuxostat mol­ecules in polymorphs and multi-component structures, indicated by the torsion angle τ.

Form	CSD	τ (°)	Ref.
Polymorph Q	HIQQAB	−174.1	Maddileti et al. (2013 ▸)
Polymorph H1	HIQQAB02	177.9	Yadav et al. (2017 ▸)
		−1.2
MeOH solvate (173 K)	CCDC 1981184	5.6	Gelbrich et al. (2020a ▸)
MeOH solvate (296 K)	UREQOY	5.0	Jiang et al. (2011 ▸)
EtOH solvate (I)	–	4.5	This study
Acetic acid solvate (173 K)	CCDC 1981185	−2.8	Gelbrich et al. (2020b ▸)
Acetic acid solvate (296 K)	XULRUT	−3.2	Wu et al. (2015 ▸)
Pyridine solvate	PUHGUV	2.7	Zhu et al. (2009 ▸)
Acetamide co-crystal	HIQQEF	−6.9	Maddileti et al. (2013 ▸)
Nicotinamide co-crystal	HIQQIJ	0.7	Maddileti et al. (2013 ▸)
4-Amino­benzoic acid co-crystal	HIQQOP	−176.9	Maddileti et al. (2013 ▸)
Urea co-crystal	HIQQUV	4.4	Maddileti et al. (2013 ▸)
Isonicotinamide co-crystal	OYADAV	−3.8	Kang et al. (2017 ▸)
2-Methyl-1H-imidazole salt	FAMQIW	−19.4	Zhang & Zhang (2017 ▸)
		13.4
Imidazole salt monohydrate	KIPMAA	−5.7	Gao et al. (2019 ▸)
2-(Pyridin-2-yl­amino)­pyridinium salt	FAMQOC	−174.5	Zhang & Zhang (2017 ▸)