Possible importance of a “metal-surface selection rule” in the interpretation of the infrared spectra of molecules adsorbed on particulate metals; infrared spectra from ethylene chemisorbed on silica-supported metal catalysts

Synthesis of organometallic compounds in gas phase presents a novel guideline to preparative chemists because they can be prepared without solvent and oxidation in air. Especially, the application of the laser vaporization to the gas-phase synthesis of organometallic compounds enables us to prepare the constituents in considerable density in a short time because there are no interfering effects of solvents, aggregation phenomena, and counter ions. This new approach should open up an entirely different aspect of organometallic chemistry and physics, which can be studied quite nicely in the gas phase, and indeed several groups independently have succeeded in the synthesis of novel organometallic complexes.1-7 The technique used to produce and detect the gas- phase organometallic clusters involves a beam source with laser vaporization of metal rods and time-of-flight mass spectrometry whose distinct ability was well-demonstrated in the discovery of C60 8 and metallo-carbohedrene,9,10 a so-called met-car.

A Novel Network Structure of Organometallic Clusters in the Gas Phase

Publisher Summary This chapter discusses the analysis of the vibrational spectra of organometallic compounds formed by the metals and hydrocarbons of general formula (CH)n. The unsaturated character of these ring systems implies the presence of highly delocalized electrons called the π electrons. Most of the complexes discussed in this chapter belong to the group of compounds called “π complexes,” because the π electrons of the ligands are responsible for bond formation. Ring systems with four, six, seven, and eight CH groups are shown to undergo complex formation with suitable metals. The chapter describes the theoretical considerations in the analysis of vibrational spectra, the principles of molecular spectroscopy, and interpretation of observed spectra. The techniques of infrared and Raman spectroscopy and the general aspects of the analysis of the spectra of π complexes of cyclic systems, CnHn, are also discussed. Experimental results for three-membered rings, four-membered rings, five-membered rings, six-membered rings, seven-membered rings, and eight-membered rings are presented.

Infrared and Raman Spectral Studies of π Complexes Formed Between Metals and CnHnRings

A soft-landing experiment on organometallic cluster ions: infrared spectroscopy of V(benzene)2 in Ar matrix

The molecular vibrations of dibenzene chromium are analyzed in terms of the eclipsed 25 atomic model of symmetry D6h with planar ligands. A complete set of symmetry coordinates is constructed and based almost entirely on conventional types of valence coordinates. A harmonic force field is given, and is used to calculate the vibrational frequencies, mean amplitudes of vibration, and perpendicular amplitude correction coefficients for (C6H6)2Cr and (C6D6)2Cr.

W Lüttke

Papers

IR-und Raman-untersuchungen zur struktur des di-benzol-chroms, seines kations sowie verwandter verbindungen