For the therapeutic importance of pyrazoles, see: Sil et al. (2005) ; Haddad et al. (2004) . For their diverse pharmacological activities, see: Bekhit et al. (2012) ; Castagnolo et al. (2008) ; Ramajayam et al. (2010) . For background to the synthesis, see: Nef (1891) ; Katritzky et al. (1997) ; Wardell et al. (2007) ; de Lima et al. (2010) . For evaluation of tautomeric forms using NMR MO calculations and crystallography, see: Feeney et al. (1970) ; Hawkes et al. (1977); Freyer et al. (1983) ; Dardonville et al. (1998) ; Kleinpeter & Koch (2001) ; Bechtel et al. (1973a,b) ; Chmutova et al. (2001); Wardell et al. (2007) ; Gallardo et al. (2009); Ding & Zhao (2010) . For a previous synthesis, see : Kimata et al. (2007) . For a recently reported structure, see: Wardell et al. (2012) . Table 1 Hydrogen-bond geometry (Å , ).