3-[4-Phenoxyphenyl]pyrazole (Hpzpp) and 3-[4-butoxyphenyl]pyrazole (Hpzbp) in rhodium chemistry crystal structures of 3-[4-phenoxyphenyl]pyrazole, and [Rh(μ-pzbp)(COD)]2

Stereoselective formation and catalytic activity of hydrido(acylphosphane)(chlorido)(pyrazole)rhodium(iii) complexes. Experimental and DFT studies

Stereoselectivity assisted by hydrogen bond formation, inhibited by steric hindrance, predicted by DFT calculations.

Tetrahedral Zinc Complexes with Liquid Crystalline and Luminescent Properties: Interplay Between Nonconventional Molecular Shapes and Supramolecular Mesomorphic Order

Novel metallomesogens with luminescent properties and liquid crystalline behavior at room temperature have been achieved by the preparation of zinc complexes with polycatenar pyrazole and bis(pyrazolyl)methane ligands. Their molecular structures do not have a conventional shape in that they are far from the typical rod-like and flat disc-like geometries of common liquid crystals. They consist of a nonplanar nucleus due to the methylene spacer and/or the coordination to the tetrahedral center, as confirmed by single crystal analysis of the cores. The different numbers and positions of side chains in the pyrazole ligand enabled us to access lamellar and columnar mesophases and, of particular interest, to obtain columnar arrangements at room temperature. Supramolecular models for the organization of the molecules in the mesophases are proposed on the basis of the small-angle XRD diffractograms. The zinc complexes display luminescence in the near UV-blue region with large Stokes shifts. An interplay between non-conventional molecular shapes (due to the tetrahedral core) and the supramolecular mesomorphic order (due to the ligand design) led to materials that interestingly embody two rather opposite properties, a columnar self-organizational ability and luminescence with weak intermolecular interactions.

Unusual Ar−H/Rh−H JHH NMR Coupling in Complexes of Rhodium(III): Experimental Evidence and Theoretical Support for an η1−Arene Structure

The synthesis and structural properties of three new hydridorhodium(III) complexes are reported. Hydrogenolysis of the cyclometalated rhodium dichloride complexes [RhCl(2)[(S,S)-benbox(Me(2))]] (2a-c) leads to formation of the new complexes [RhCl(2)(H)[(S,S)-ip-benbox(Me(2))H]] (3a-c) in 45% to 85% yield. Compounds 3a-c were found to have unusual features by NMR spectroscopy: in particular, downfield shifted aryl proton resonances (8.88-9.03 ppm) that were coupled to the rhodium hydride resonances. Using X-ray crystallographic studies, a variety of solid- and solution-state characterization techniques, and DFT calculations, these features were attributed to the presence of weak pi-type eta(1)-arene interactions in 3a-c.