Experimental measures of the electron distribution and bonding in bis(/eta//sup 5/-cyclopentadienyl) osmium from He(I) and He(II) valence photoelectron spectroscopy

Journal Article · Sat Jul 15 00:00:00 EDT 1989 · J. Chem. Phys.; (United States)

OSTI ID:6095001

Lichtenberger, D L; Copenhaver, A S

The He(I) and He(II) high resolution photoelectron spectra of osmocene are reported. Vibrational fine structure is observed in all the valence metal-based ionizations and in the cyclopentadienyl ..pi.. ionizations which derive from the /ital e//sub 1/ital g// and /ital e//sub 1/ital u// symmetry combinations. Analysis of the vibrational progressions found in the metal-based ionizations provides a measure of the force constants and vibrational frequencies for the metal--ring stretch in the positive ions. The vibrational analysis for the /sup 2//ital E//sub 2(5/2)/ and /sup 2//ital E//sub 2(3/2)/ states of the osmocene cation (derived from the spin--orbit split ionization of the metal /ital e//sub 2/ital g//(/ital d//sub /ital x//sup 2//minus//ital y2//, /ital d//sub /ital xy//) set) indicates an 0.12 A greater metal--ring bond length in the cation compared to the neutral molecule. The sharp /sup 2//ital A//sub 1(1/2)/ ionization (correlating with removal of an electron from the metal /ital a//sub 1/ital g//(/ital d//sub /ital z/ /sup 2//) orbital) is observed to have a much shorter vibrational progression. The adiabatic ionization is the most intense (vertical) band of the series, indicating that there is no appreciable change in metal--ring bond distance upon ionization from the nonbonding /ital a//sub 1/ital g//(/ital d//sub /ital z/ /sup 2//) orbital to produce the /sup 2//ital A//sub 1(1/2)/ cationic state. A large spin--orbit coupling is observed in the metal ionization region and a moderate amount in the cyclopentadienyl ring ..pi.. ionization region. From evaluation of the spin--orbit coupling, the ionization band which correlates primarily with the /ital e//sub 1/ital g// combination of the cyclopentadienyl ..pi.. orbitals is shown to contain about 27% metal character.

• Research Organization: Laboratory for Electron Spectroscopy and Surface Analysis, Department of Chemistry, University of Arizona, Tucson, Arizona 85721(US)
• OSTI ID: 6095001
• Journal Information: J. Chem. Phys.; (United States), Vol. 91:2
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ORGANOMETALLIC COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
OSMIUM COMPOUNDS
CHARGE DISTRIBUTION
CHEMICAL BONDS
COVALENCE
ELECTRONIC STRUCTURE
L-S COUPLING
PHOTOIONIZATION
STRUCTURAL CHEMICAL ANALYSIS
VIBRATIONAL STATES
COUPLING
ELECTRON SPECTROSCOPY
ENERGY LEVELS
EXCITED STATES
INTERMEDIATE COUPLING
IONIZATION
ORGANIC COMPOUNDS
REFRACTORY METAL COMPOUNDS
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
400102* - Chemical & Spectral Procedures