Supramolecular Arrays of Cationic Complexes Containing Pyrazole Ligands and Tetrafluoroborate, Trifluoromethanesulfonate, or Nitrate as Counterions. Crystal Structure of Bis(3,5‐dimethyl‐4‐nitro‐1H‐pyrazole‐κN²)silver(1+) Nitrate ([Ag(Hpz^NO2)₂](NO₃))

Abstract

, 4) were comparatively analyzed to determine the factors responsible for polymeric assemblies. In all cases, the H-bonding interactions between the pyrazole moieties and the appropriate counterion and, in particular, the orientation of the NH groups of the pyrazole ligands are determinant of one-dimensional polymeric arrays. In this context, the new compound [Ag(Hpz NO2 ) 2 ](NO 3 ) (5) was synthesized and its structure analyzed by X-ray diffraction (Fig. 4). The Hpz NO2 serves as N-monodentate ligand, which coordinates to the Ag I center through its pyrazole N-atom giving rise to an almost linear NÀAgÀN geometry. The planar NO À 3 counterion bridges two adjacent Ag I centers to form a one-dimensional zigzag-shaped chain which is also supported by the presence of NÀH ¥¥¥ O bonds between the pyrazole NH group of adjacent cationic entities and the remaining O-atom of the bridging NO À 3 (Fig. 5). The chains are further extended to a two-dimensional layer-like structure through additional Ag ¥¥¥ O interactions involving the NO 2 substituents at the pyrazole ligands (Fig. 6).

The 3,5-dimethyl-4-nitropyrazole ligand in the construction of supramolecular networks of silver(I) complexes

“…Following the literature data and our own research results [6,[8][9][10], we have found in all cases a linear N-Ag-N coordination with a cis, trans or intermediate cis-trans orientation of the two NH groups from the two pyrazole ligands (deduced from the torsion angle s defined by the four nitrogens of the two pyrazoles [8]), which is determinant of the supramolecular assembly. In particular, in the complex cis-½AgðHpz bp 2 Þ 2 ½BF 4 (1) ðHpz bp 2 ¼ 3; 5-diðp-butoxyphenylÞpyrazoleÞ both pyrazole ligands are hydrogen-bonded to the same counteranion BF 4 À giving rise to closed molecular unities, which are bonded through additional weaker intermolecular C-HÁ Á ÁF contacts in a 1D framework (Fig.…”

“…1c) [6,8] AgÁ Á ÁO interactions involving the CFSO 3 À counteranion), and these dimers assembled in columns by pÁ Á Áp (NO 2 Á Á Á NO 2 ) contacts (Fig. 1c).…”

“…In particular, in the complex cis-½AgðHpz bp 2 Þ 2 ½BF 4 (1) ðHpz bp 2 ¼ 3; 5-diðp-butoxyphenylÞpyrazoleÞ both pyrazole ligands are hydrogen-bonded to the same counteranion BF 4 À giving rise to closed molecular unities, which are bonded through additional weaker intermolecular C-HÁ Á ÁF contacts in a 1D framework (Fig. 1a) [6,8]. By contrast, in the related complex trans-½AgðHpz Me 2 Þ 2 ½NO 3 (2) ðHpz Me 2 ¼ 3; 5-dimethylpyrazoleÞ the cationic units are linked by bridging NO 3 À groups in a zig-zag polymeric 1D chain involving strong N-HÁ Á ÁO hydrogen-bonds ( Fig.…”

“…Previous works in our lab have been dealt with the study of the molecular assembly of several ionic metal complexes based on substituted pyrazole ligands, in which the hydrogen-bonds between the counteranion and the NH-pyrazole groups were the main tool for the molecular assembly [5][6][7][8], although some other factors as variations of the counteranion and substituents on the pyrazole ligands also drove the supramolecular arrangement. In this work, we extend the potentiality of new ionic silver complexes based on the 3,5-dimethyl-4-nitropyrazole ðHpz NO 2 Þ ligand for a rational design of extended hydrogen-bonding polymers or supramolecular arrays established on coordinative, pÁ Á Áp and/or non-conventional hydrogen-bond interactions.…”

Pyrazole-based allylpalladium complexes: Supramolecular architecture and liquid crystal behaviour

“…Each BF À 4 group bridges two cationic entities, as it had been observed in related compounds exhibiting polymeric chains and an torsion angle s of ca. 180° [16][17][18]. However, at difference to those, in our compound, two BF À 4 counteranions bond the same two cationic unities so generating dimers through these N-H Á Á ÁF interactions (Fig.…”