Creating Solid Solutions of Metallocenes: Migration of Nickelocene into the Ferrocene Crystal Lattice in the Absence of a Solvent

Abstract

Ferrocene and nickelocene do not react with each other in solution; however, the large impact of the paramagnetic component on the ferrocene 1H NMR signal linewidth and relaxation times has been quantified. Co-crystallization of ferrocene and nickelocene at any ratio from a solvent can be explained with both pure substances crystallizing in the same space group P21/n. As a new phenomenon, when a ferrocene single crystal is exposed to polycrystalline nickelocene in the absence of a solvent, the nickelocene migrates into the ferrocene crystal lattice and a mixed crystal is formed that retains its macroscopic shape. This process has been proven visually by cutting the single crystal. Mixing polycrystalline ferrocene with polycrystalline nickelocene at different molar ratios with a mortar and pestle leads to crystalline solid solutions with the corresponding molar ratios of both components. This migration of one organometallic component into an existing crystal lattice of another at ambient temperature in the absence of a solvent has not been described previously. Paramagnetic 1H solid-state NMR spectroscopy of static and rotating samples of dry ferrocene/nickelocene mixtures at varying ratios is used to prove and quantify the mixing of both metallocenes at the molecular level. A single-crystal X-ray structure of a 50/50 mixed crystal corroborates the NMR results that nickelocene and ferrocene are randomly distributed in the lattice and that the space group P21/n is retained. All ferrocene molecules in the mixed crystal lattice show a broadening of their 1H wideline signals and residual magic-angle spinning (MAS) lines at ambient temperature. The broadening of the ferrocene signals correlates with the nickelocene content. 1H T 1 relaxation time measurements for the signals of ferrocene in samples with different amounts of nickelocene corroborate the assumption that the signal broadening is due to paramagnetic dipole–dipole relaxation of ferrocene molecules in the vicinity of nickelocene. Spatially separated ferrocene and nickelocene powders in one rotor show the solid-state NMR characteristics of the individual polycrystalline metallocenes. The described formation of solid solutions of metallocenes in the absence of a solvent will open new pathways to homogeneously mixed nanoparticles with desired metal ratios and dual-atom catalysts.

Adsorption of solid phosphines on silica and implications for catalysts on oxide surfaces

“…Only one example of isostructural solid metallocenes forming solid solutions at ambient temperatures has been described. 38…”

“…Only one example of isostructural solid metallocenes forming solid solutions at ambient temperatures has been described. 38 Fig. 3 13 C CP/MAS spectra of polycrystalline PPh 3 (1, top) and surfaceadsorbed PPh 3 (1a, bottom) at 4 kHz spinning speed.…”

“…As an additional proof that polycrystalline 1 assumes a different physical state when adsorbed on the silica surface, the 31 P T 1 relaxation times of 1 and 1a, obtained by inversion recovery techniques, 19,38 were compared. While the T 1 time of polycrystalline 1 is about 1000 s, 32 it is merely 0.59 s when 0.1 g of the phosphine is adsorbed on 1 g of silica (Fig.…”

Surface-Assisted Selective Air Oxidation of Phosphines Adsorbed on Activated Carbon

“…When oxygen is admitted, the phosphines are oxidized to the corresponding phosphine oxides. It will be demonstrated that AC-adsorbed P n Bu 3 (1), PEt 3 (2), P n Oct 3 (3), PMe t Bu 2 (4), PCy 3 (5), and PPh 3 (6) (Figure 2) can be oxidized selectively by air to give clean phosphine oxides 1 ox −6 ox (Figure 1). To achieve clean oxidation, the phosphines are first adsorbed in a mono-or submonolayer on the AC surface.…”

“…Adsorption of molecules on surfaces is a crucially important process with wide-ranging applications in academia and industry. Therefore, new developments in the separation sciences, as well as physical and analytical chemistry, appear frequently in the chemical literature. − Volatile adsorbates can be removed in vacuo, while washing with favorable solvents removes nonvolatile adsorbates.…”