Supramolecular structures of rhenium(I) complexes mediated by ligand planarity via the interplay of substituents. Issue 9 (6th August 2018)

• Record Type: Journal Article
• Authors: Mark-Lee, Wun Fui; Chong, Yan Yi; Kassim, Mohammad B.
• Is Part Of: Acta crystallographica. Volume 74:Issue 9(2018)
• Page Start: 997
• Page End: 1006
• Publication Date: 2018-08-06
• Subjects: rhenium(I) complexes -- supramolecular architectures -- planarity -- weak interactions -- Hirshfeld surface analysis -- computational chemistry -- n‐to‐π* -- crystal structure -- tubular column; Crystallography -- Periodicals; Crystals -- Periodicals; 548.3
• DOI: 10.1107/S2053229618010586
• Languages: English
• ISSNs: 2053-2296

Abstract

Abstract : The fluoro and nitro substituents on the phenyl ring of the 1‐(4‐fluorocinnamoyl)‐3‐(pyridin‐2‐yl)pyrazole ligand influence the planarity, interactions and also the molecular packing of its rhenium(I) complexes. Abstract : The crystal and molecular structures of two Re I tricarbonyl complexes, namely fac ‐tricarbonylchlorido[1‐(4‐fluorocinnamoyl)‐3‐(pyridin‐2‐yl‐κ N )pyrazole‐κ N 2 ]rhenium(I), [ReCl(C17 H12 FN3 O)(CO)3 ], (I), and fac ‐tricarbonylchlorido[1‐(4‐nitrocinnamoyl)‐3‐(pyridin‐2‐yl‐κ N )pyrazole‐κ N 2 ]rhenium(I) acetone monosolvate, [ReCl(C17 H12 ClN4 O3 )(CO)3 ]·C3 H6 O, (II), are reported. The complexes form centrosymmetric dimers that are linked into one‐dimensional columns by C—H…Cl and N—O…H interactions in (I) and (II), respectively. C—H…Cl interactions in (II) generate two R 2 1 (7) loops that merge into a single R 2 1 (10) loop. These interactions involve the alkene, pyrazole and benzene rings, hence restricting the ligand rotation and giving rise to a planar conformation. Unlike (II), complex (I) exhibits a twisted conformation of the ligand and a pair of molecules forms a centrosymmetric dimer with an R 2 2 (10) loop via C—H…O interactions. The unique supramolecular structures of (I) and (II) are determined by their planarity and weak interactions. The planar conformation of (II) provides a base for appreciable π–π stacking interactions compared to (I). In addition, an N—O…π interaction stabilizes the supramolecular structure of (II). We report herein the first n →π* interactions of Re I tricarbonyl complexes, which account for 0.33 kJ mol −1 . Intermolecular C—H…Cl and C—H…O interactions are present in both complexes, with (II) showing a greater preference for these interactions compared to (I), with cumulative contributions of 48.7 and 41.5%, respectively. The influence of inductive (fluoro) and/or resonance (nitro) effects on the π‐stacking ability was further supported by LOLIPOP (localized orbital locator‐integrated π over plane) analysis. The benzene ring of (II) demonstrated a higher π‐stacking ability compared to that of (I), which is supported by the intrinsic planar geometry. The HOMA (harmonic oscillator model of aromaticity) index of (I) revealed more aromaticity with respect to (II), suggesting that NO2 greatly perturbed the aromaticity. The Hirshfeld fingerprint (FP) plots revealed the preference of (II) over (I) for π–π contacts, with contributions of 6.8 and 4.4%, respectively.