Synthesis and Crystal Structures of Rhomb-Shaped Dimeric Pd(II) Complexes with Arylethynyl-Substituted 2,2′-Bipyridine through CH⋯π Interactions in the Crystalline States

Abstract

Two molecular structures of a complex C26H16Cl2N2Pd (1) with a benzene hemisolvate (1•0.5C6H6) and a complex C34H20Cl2N2Pd (2) revealed similar conformations: one side of the arylethynyl group is flat to the bipyridine plane while the other side of the arylethynyl group is highly twisted to the plane because rhomb-like dimer fragments are formed between respective two complexes through CH⋯π interactions. The Hirshfeld surface analysis indicates that the most important contributions for the crystal packing of 1 are from H⋯H (33.6%), C⋯H/H⋯C (28.3%), Cl⋯H/H⋯Cl (17.8%), and C⋯C (10.6%) interactions and those of 2 are from H⋯H (36.5%), C⋯H/H⋯C (26.0%), Cl⋯H/H⋯Cl (15.7%), and C⋯C (12.3%) interactions, indicating the remarkable CH⋯π and electron distribution of molecules by Cl ions. The benzene solvate molecule of 1•0.5C6H6 performs to fill the internal space instead of the naphthyl group. Detailed crystallographic and DFT studies were performed to understand the molecular structures and the corresponding supramolecular associations.

Synthesis and π-Hole vs. π Effects of Pt(II) Complexes with Pentafluorophenyl and Phenyl-Substituted Bipyridines

“…The compounds 1b, 2, and [PtCl 2 (dmso) 2 ] were prepared following previously reported protocols [39,40]. 4,4 ′ -Bis(pentafluorophenyl)-2,2 ′ -bipyridine (1a) was prepared via Suzuki-Miyaura cross-coupling reaction.…”

“…Both complexes exhibited a min sition shoulder at 520 nm, consistent with the complexes' reddish color. The absorption spectra of ligand 2 and its related metal complexes [MCl22] and Pd [40]) are shown in Figure 2. The peaks for ligand 2 indicate sharper vib transitions, featuring at least four strong bands at 265 (ε = 31,200 M -1 cm -1 ), 282 (38 1 cm -1 ), 298 (37,700 M -1 cm -1 ), and 320 (sh, 9400 M -1 cm -1 ) nm, attributed to π-π* tra of the pyridine and pentafluorophenyl groups for 2a (Figure 2a).…”

“…In the crystal of [PtCl 2 2b]•0.5C 6 H 6 , the asymmetric unit contains a whole complex and one half of benzene (see Figure 11), indicating the isomorph structure of [PdCl 2 2b]•0.5C 6 H 6 [40]. The complex comprises one Pt(II) ion, two Cl − ions, and one ligand to give a mononuclear complex, [PtCl…”

“…The ability of these molecules to coordinate with Pt(II) ions opens innovative research fields [29][30][31][32]. However, despite the interest in and development of coordination compounds reported in the recent literature, those featuring acetylene cross-linking are still lagging behind as there are still few reports [33][34][35][36][37][38][39][40]. The use of an acetylene linker offers the enticing prospect of modulating the aromatic plane's rotational barrier, significantly affecting the molecule's physical and chemical properties.…”

“…The use of an acetylene linker offers the enticing prospect of modulating the aromatic plane's rotational barrier, significantly affecting the molecule's physical and chemical properties. Such fields prompted us to develop the investigation of phenylethynyl-substituted bipyridine to understand the supramolecular association of aromatic moieties [39] and the corresponding Pd(II) complex [40] through the electrostatic π-interactions.…”