Spectra Of Ferrocene Research Articles

Solvent contribution to ferrocene conformation: Theory and experiment

Solvent impacts on ferrocene configuration and the nature of its component energies. The measured infrared (IR) spectra of ferrocene (Fc) in the region 400-500 cm−1 exhibit very different profiles in gas phase and in solutions. The present study further explores such the differences in gas phase and in solutions using combined theoretical calculations and experimental measurements. It concentrates on the IR spectra in the region of 400–1200 cm−1 using non-polar (tetrachloromethane (CCl4) and n-hexane (Hex)) and polar (acetonitrile (ACN), dichloromethane (DCM), tetrahydrofuran (THF) and 1,4-dioxane (DOX)) solvents. Six relatively intense normal modes in this region (ν7, ν8,9, ν18, ν22,23, ν30,31 and ν37 at approximately 482, 495, 815, 840, 1006, 1110 cm−1) were obtained. The dependence of the relative energies of the eclipsed and staggered rotamers of Fc on the polarity of the solvent is small. Analysis of the band profile for the vibrational modes in the 480-500 cm−1 region (ν7, ν8,9) using the reaction coordinate model suggests that the energy difference between the eclipsed and staggered rotamers (ΔEe-s solv) may be underestimated by implicit solvent model in the calculations. Further investigation in this direction is warranted. The impact of solvation on Fc configuration is further investigated using energy decomposition analysis (EDA) in a non-polar (tetrachloromethane (CCl4)) and a polar (acetonitrile (ACN)) solvent. These calculations suggest that solvation substantially changes the electrostatic and quantum mechanical Pauli energy contributions to the interaction energy of Fc conformers, which result in a large steric energy in solvents to enhance the dominance of the eclipsed Fc, an observation consistent with the analysis of the bands due to the ν7 and ν8,9 vibrational modes.

Dominance of eclipsed ferrocene conformer in solutions revealed by the IR spectra between 400 and 500 cm-1

A combined Fourier transform infrared (FTIR) spectra of ferrocene (Fc) and density functional theory (DFT) based quantum mechanical calculations confirmed the dominance of the eclipsed Fc conformer in the fingerprint region of 400–500 cm−1 in solutions. Solution IR spectra of Fc measured in acetonitrile (ACN, ε = 35.69), dichloromethane (DCM, ε = 8.93), tetrahydrofuran (THF, ε = 7.43) and dioxane (DOX, ε = 2.21) show two well-defined bands in the 480-500 cm−1 region with the higher-wavenumber band higher in intensity. The band profile agrees well with the earlier IR spectra of Lippincott and Nelson (1958) in tetrachloromethane solution as well as more recent measurement in dichloromethane solution of Duhović and Diaconescu (2013). DFT based quantum mechanical calculations predict that the eclipsed (D5h) Fc conformer is lower in energy than the staggered (D5d) conformer and that the room-temperature solution spectrum of Fc is dominated by that of the D5h form (Best et al., 2016). The present study confirms that solvent effects enhanced the dominance of the D5h Fc conformer which resulted in switch of the IR profile patterns in 400–500 cm−1, from low-wavenumber band higher in intensity pattern in gas phase to higher-wavenumber band higher in intensity in solutions. It further suggests that the effects of solvents on the IR spectra of Fc in this region are small and the solvent model effects are also small for the IR spectrum in the region of 400–500 cm−1 of Fc.

Molecular dynamics study of ferrocene topology under various temperatures

AbstractWe present the first quantum mechanical Atom‐Centered Density‐Matrix Propagation molecular dynamic (MD) study to investigate ferrocene (Fc) conformation in gas phase. The MD simulations were performed at several temperatures (7, 18, 80, 120, 180, 293, and 500 K) for a period of 10 ps. It is found that, at very low temperatures (≤18 K), ferrocene prefers eclipsed‐like conformation. At higher temperatures (>18 K), the cyclopentadienyl rings (Cp) of ferrocene exhibit apparent fluxional rotations, leading to configurations with the rotational angle δ distributing within a range of 0° (eclipsed) to 18° (approximately half of 36° for the staggered conformation), accompanied by the cyclopentadienyl ring tilt up to approximately 12° at 500 K. The simulated mean inferred (IR) spectrum of ferrocene at 7 K is clearly dominant by a doublet‐splitting band of eclipsed‐like Fc features in the region of 400 to 600 cm−1, in agreement with previous IR studies. The animation obtained from the MD simulations indicates that, at room temperature, the Fe‐C distances in ferrocene are in fact not strictly congruent but 2:2:1‐fold.

Polymerization of Ferrocene in an Electrodeless High-Frequency Discharge Helium Plasma: II. 1 Structure and Crystallization Dynamics of Plasmochemically Polymerized Films

The main frequencies in the IR spectra of ferrocene and plasmochemically polymerized ferrocene films obtained in the plasma of an electrodeless high-frequency discharge in mixtures of helium and ferrocene are the same. The appearance in the IR spectra of the films of weak bands is associated with partial decomposition of ferrocene molecules in the high-frequency discharge plasma.

Ferrocene-zeolite interactions measured by inelastic neutron scattering

The measured inelastic neutron scattering vibrational spectrum of ferrocene, Fe(C5H5)2, in the supercages of KY zeolite is compared with that of solid ferrocene. Only small differences between these spectra are observed. It is shown that these differences are compatible with those calculated by ab initio calculations taking account only of the geometry of the ferrocene and ignoring the molecular environment. We conclude that the ferrocene–zeolite interactions are rather weak, and comparable with the intermolecular interactions in solid ferrocene.

Vibrational Overtone Spectroscopy of Metallocenes and “Half-Sandwich” Organometallic Complexes

The FTIR spectra of ferrocene, ruthenocene, cyclopentadienyl manganese tricarbonyl (CPMT), cyclopentadienyl titanium trichloride (CPTT), and cyclopentadienyl iron dicarbonyl iodide (CPIDI) CCl4 solutions are presented at the first and second overtone region (Δv = 2, 3). The gaseous ferrocene, ruthenocene, and CPMT spectra are also presented at the third overtone region (Δv = 4) recorded by intracavity photoacoustic spectroscopy. Assignments for the observed transitions are suggested for the liquid and reevaluated for the gas-phase spectra. The influence of the metal and other ligands attached to the metal on the vibrational behavior of the cyclopentadienyl ring is also discussed.

Electronic transitions in metallocenes by resonance Raman scattering. Part 1.—Analysis of the ferrocene spectrum in the visible region

Resonance Raman (RR) spectra of ferrocene in three different solvents have been measured and the excitation profiles for two totally symmetric molecular vibrations derived. These latter have also been reproduced by calculations together with the visible absorption spectrum. The model we used in these calculations, based on the non-adiabatic vibronic-coupling approach, is presented and discussed.

Spectroscopy at very high pressures. part 25. the infrared spectrum of ferrocene at high pressures

Spectroscopy at very high pressures. part 25. the infrared spectrum of ferrocene at high pressures

Low temperature infrared spectrum of ferrocene- h10 and - d10

The low temperature i.r. spectrum of ferrocene has many features not consistent with the room temperature structure. Some changes in the vibrational assignment are made. The e 1 u ring-metal-ring deformation is observed at 179 cm −1 and the spectroscopic entropy is corrected accordingly.

Electron Spectroscopy of Open-Shell Systems: Spectra of Ni(C5H5)2, Fe(C5H5)2, Mn(C5H5)2, and Cr(C5H5)2

The high resolution HeI electron spectra of Ni(C5H5)2, Fe(C5H5)2, Mn(C5H5)2, and Cr(C5H5)2 have been recorded and analyzed in terms of a molecular orbital description of the electronic structure. The ground state electronic configurations have been assigned by considering the feasible ground state configurations, determining the number and type of ionic states obtained from ionization of these configurations, and then comparing the predicted transitions with those observed experimentally. The ground state configuration and adiabatic first ionization potential of these molecules are: Cr(C5H5)2, ··· (e2g)3(a1g)1, 3E2g, I.P.=5.50 eV; Mn(C5H5)2, ··· (e2g)4 (a1g)1, 2A1g, I.P.=6.55 eV; Fe(C5H5)2, ··· (a1g)2 (e2g)4, 1A1g, I.P.=6.72; Ni(C5H5)2, ··· (a1g)2 (e2g)4 (e1g)2, 3A2g, I.P.=6.2 eV. Vibrational structure has been observed in the spectrum of ferrocene and is assigned to progressions in ν4, the symmetric ring-metal stretching mode.

Influence of substituents on the shifts of the absorption bands in the spectra of monosubstituted ferrocenes

1. The substituents expert a weak influence upon the positon and intensity of the absorption bands in the spectrum of ferrocene. Substantial differences were detected in the influence of substituents upon the bands of the ultraviolet region of the spectrum of (II) and (III) and on the bands of the visible portion of the spectrum of (IV and V). 2. A great similarity in the influence of substituents upon the band III in the spectra of monosubstituted ferrocenes and the band at approximately 200 mμ (benzene band) in the spectra of substituted benzenes was demonstrated.

Beschreibung des Feldgradienten in Fe(C5H5)2 und [Co(C5H5)2]+ durch die Ligandenfeldtheorie

The electric field gradients at the metal nuclei in the isoelectronic compounds Fe(C5H5)2 and [Co(C5H5)2]+ are computed, using a modified electrostatic model (Ligand Field Theory). The direct contribution of the (1S 3d6) state is diminished by the influence of the lattice, covalency, and STERNHEIMER polarization. The results of this work are, expressed in a. u., at the Co3+ site 1.81 and at the Fe2+ 1.37, which are to be compared with the experimental ones, 1.67 and 1.25 (Q=0.18b) resp. 0.78 (Q=0.29 b). The behaviour of the 3d electrons in the strong crystalline field is also used to explain the spectra of ferrocene.