Synthesis and Characterization of Bis(2,2‘-bipyridyl)platinum(I):  A Novel Microtubular Linear-Chain Complex

Abstract

One-electron reduction of [Pt(bpy)2]2+ (bpy = 2,2‘-bipyridyl) in aqueous solution results in the formation of black-green lustrous needles on solid electrodes. The crystalline needles grow perpendicularly from the substrate surface and reach lengths of 1−2 cm. Elemental analysis, X-ray photoelectron spectroscopy, and electrochemical measurements indicate that the new compound is a genuine PtI complex with a d9 electronic configuration and with the composition [Pt(bpy)2]NO3·2H2O. X-ray crystallographic analysis shows that the crystalline needles consist of linear chains of discrete [PtI(bpy)2] units with a Pt−Pt distance of 3.563(1) Å and with each bipyridyl ligand overlapping face-to-face (eclipsed) with its nearest neighbor. At the monomeric level, the structure of [PtI(bpy)2] units exhibits a distorted square-planar configuration with structural parameters very similar to those of the parent PtII complex, [Pt(bpy)2](NO3)2·H2O. The new linear-chain compound was prepared by chemical and electrochemical methods. The resulting crystals are relatively stable in air but oxidize slowly over a period of weeks. Scanning electron microscopy reveals that the crystals are tubular with a hollow near-hexagonal morphology. Cooperative effects influence the optical and electrical properties of the crystals. Because of extensive solid-state interactions between stacked monomeric [PtI(bpy)2] units, the crystals absorb strongly over the whole visible region and far into the near infrared. Their room temperature electrical conductivity is relatively high, 10 Ω-1 cm-1.

Cationic Two-Coordinate Complexes of Pd(I) and Pt(I) Have Longer Metal-Ligand Bonds Than Their Neutral Counterparts

“…23,24 A single report exists of a monomeric Pt(I) complex, namely [(bipy) 2 Pt] + (bipy = 2,2 0 -bipyridyl). 25 Although it contains potentially redox non-innocent bipyridine ligands, the original experimental evidence and our calculations 26 agree on the Pt(I) assignment ( Figure S7). Monomeric Pd(I) complexes have been proposed as intermediates in some reactions of Pd(0) complexes with alkyl halides as early as the 1970s 27 and more recently in reactions of Pd(0) complexes…”

The Early Years of 2,2′-Bipyridine—A Ligand in Its Own Lifetime

“…Nevertheless, a number of [Pt(bpy) 2 ] 2+ salts have been prepared and structurally characterized and the ways in which the complexes adapt to minimise the steric interactions are of considerable interest. In some cases, the electronic demands of the bpy ligand to maximize conjugation in a planar conformation dominates and the geometry of the PtN 4 motif in the [Pt(bpy) 2 ] 2+ cation is distorted towards tetrahedral, with least squares planes angles between the near-planar bpy ligands between 30 and 37° (Figure 19a) [171,172,173]. In other cases, the electronic preference of the d 8 metal centre for a square-planar PtN 4 motif dominates, and the bpy adopts a V-shaped conformation about the interannular C–C bond (Figure 19b) [174,175,176,177,178,179].…”

Homogeneous catalysis of platinum(II) complexes in photochemical hydrogen production from water

“…13). In the earlier studies, relatively simple models (28)(29)(30)(31) were developed and their photo-hydrogen-evolving activities were tested [22,37]. However, it was found that these compounds do not preserve the important photochemical properties required to enhance the visible-light-induced charge separation process: the strong electronic coupling between the Ru(bpy) 3 2+ -like moiety and the heavy Pt ion promotes the quenching of the 3 MLCT excited state of the Ru(bpy) 3 2+ -like moiety [26].…”