Supramolecular first-row transition metal complexes of 3-(3,5-dimethylpyrazol-1-yl)propanamide: Three different coordination modes

Trifluoromethylated 3‐(Pyrazol‐1‐yl)propanamide (PPA) Ligands

“…The asymmetric unit contains one distinct CF 3 MePPA molecule with the trifluoromethyl and methyl groups in 3‐ and 5‐position of the pyrazole ring, respectively ( Figure 2, left). As it has been previously seen with related PPA derivatives, [14,17,18,20] the molecules are linked into an infinite assembly by hydrogen bonds. Thereby, a similar picture as for 3‐MePPA [17] and 3‐ t BuPPA [18] was observed, thus forming a one‐dimensional, ribbon‐like polymeric structure by N−H⋅⋅⋅O and N−H⋅⋅⋅N(pyrazolyl) bonds ( cf.…”

“…As it has been previously seen with related PPA derivatives, [14,17,18,20] the molecules are linked into an infinite assembly by hydrogen bonds. Thereby, a similar picture as for 3‐MePPA [17] and 3‐ t BuPPA [18] was observed, thus forming a one‐dimensional, ribbon‐like polymeric structure by N−H⋅⋅⋅O and N−H⋅⋅⋅N(pyrazolyl) bonds ( cf. Figure S2 in the Supporting Information ), while for the unsubstituted PPA [14] and Me 2 PPA [20] two‐dimensional supramolecular structures have been observed.…”

“…[9][10][11][12][13] In the course of our ongoing research on ligands based on the 3-(pyrazol-1-yl)propanamide (PPA) scaffold, we reported various transition metal complexes, showing that their coordination chemistry is diverse. [14][15][16][17][18][19] The most frequently observed coordination mode for first-row transition metals is кN,кO-chelation, [14][15][16][17][18] involving the pyrazolyl-nitrogen and amide-oxygen donor atoms (Figure 1,a). In contrast, for the less oxophilic second-row transition metals Pd [19] and Ag, [15] кN-monodentate coordination through the pyrazolyl group appeared to be most favored (Figure 1,b).…”

“…PPA Ligands are deliberately available in one step by Aza-Michael addition of the specific pyrazole derivative to acrylamide. [14,15,[17][18][19] This allows for the facile introduction of substituents at the ethylene backbone, [17] the pyrazolyl group, [17,18,20] or the amide nitrogen atom. [19] While these modifications influence predominantly the steric properties and/or the hydro-Supporting information for this article is available on the WWW under https://doi.org/10.1002/hlca.202000148 gen-bonding ability of the ligand, the electronic properties of all previously reported PPA derivatives did not differ very much.…”

“…Moreover, polydentate pyrazole‐based ligands have gained relevance as potential metalloprotein mimetics, [6–8] and as building blocks for metal‐organic frameworks [9–13] . In the course of our ongoing research on ligands based on the 3‐(pyrazol‐1‐yl)propanamide (PPA) scaffold, we reported various transition metal complexes, showing that their coordination chemistry is diverse [14–19] . The most frequently observed coordination mode for first‐row transition metals is κN , κO ‐chelation, [14–18] involving the pyrazolyl‐nitrogen and amide‐oxygen donor atoms ( Figure 1 ,a ).…”