New bis‐Pyrazole Derivatives Synthesized From Aryl‐ and Xylyl‐Linked bis(β‐Diketone) Precursors

A theoretical and experimental NMR study of the tautomerism of two phenylene-bis-C-substituted pyrazoles

“…9 More recently, similar compounds 3 and 4 but with the pyrazoles bearing substituents were synthesized by Hayter, Bray, Clegg and Lindoy (Scheme 5). 10 Finally, Thiel and co-workers also prepared the tris-derivative 5. 9,11 The tautomerism of none of these compounds were examined.…”

“…It is worth mentioning that in the related case of the para derivative 4 (R = t-Bu), the X-ray structure has been determined and corresponds to a 3,3-tautomer without proton disorder (4a). 10 Up to now, it is still very difficult to design molecules showing SSPT, because similar compounds form very different hydrogen-bonded networks.…”

5-(Biphenyl-4-yl)-3-(4-tert-butylphenyl)-1H-pyrazole

“…For related literature, see: Aggarwal et al (2003); Claramunt et al (2006); Hayter et al (2006); Stephen & Swaminathan (2006).…”

“…hydrogen bonds network in their crystals (Claramunt et al, 2006;Hayter et al, 2006). In the crystal structure of the title compound (I) (…”

Synthesis and crystal structures of copper(II) and silver(I) complexes of a semi-rigid bipyrazolyl ligand

“…Some bipyrazolide-bridged metallomacrocycles with diplatinum or dipalladium corners were reported recently [11,12]. We noticed that so far, only rigid bipyrazolyl ligands have been used in preparation of metal complexes, although flexible or semi-rigid bipyrazoles have been known for some time [13]. As pointed out by Steel, introducing some flexibility to the ligands can lead to structural motifs and topologies, which may be unavailable by using more rigid ligands [14].…”