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Photoelectron spectra and molecular orbital calculations of tricobalt alkylidyne and tri-cobalt, iron, ruthenium, and osmium sulfide nonacarbonyl and triosmium decacarbonyl clusters
Abstract
Ultraviolet photoelectron (PE) spectroscopy and molecular orbital (MO) calculations were performed on ((mu)(,3)-CR)Co(,3)(CO)(,9) (R = Cl,Br,I,H,Me,OMe), SCo(,3)(CO)(,9), SH(,n-1)Fe(,n)Co(,3-n)(CO)(,9) (n = 1,2,3), S(,2)Fe(,3)(CO)(,9), SH(,2)M(,3)(CO)(,9) (M = Fe,Ru,Os), ((mu)-H)((mu)-X)Os(,3)(CO)(,10) and ((mu)-X)(,2)Os(,3)(CO)(,10) (X = Cl,Br,I). For the ((mu)(,3)-CR)Co(,3)(CO)(,9) (R = Cl,Br,I,H,Me,OMe) the lowest ionization energy corresponds to a delocalized orbital which is both Co-C and Co-Co bonding. This ionization band is closely followed by bands due to Co-Co and Co-CO (pi) interactions. Comparison of the PE spectra of H(,3)CX, HC(TBOND)CX, C(,6)H(,5)X, and ((mu)(,3)-CR)Co(,3)(CO)(,9) for the halogens suggests that the (pi) bonding of the cobalt cluster to the apical C is closer to HC(TBOND)CX or C(,6)H(,5)X than it is to H(,3)CX. The localized MO description for these clusters can be best described with an sp-hybridized apical C, in which the lone pair forms a dative bond to the basal metal triangle and the remaining p orbitals form multicentered bonds to the Co(,3) system. In the SH(,n-1)Fe(,n)Co(,3-n)(CO)(,9) (n = 1, 2, 3) series as the Co atoms are replaced by the isoelectronic FeH unit, the PE spectra show the loss of a Co band and the appearance of an Fe band. This phenomenon suggests that the 3d bands may localize upon ionization. In a comparison with the PE spectrum of M(,3)(CO)(,12) (M = Fe,Ru,Os), the major spectral changes for SH(,2)M(,3)(CO)(,9) (M = Fe,Ru,Os) are the loss of a band corresponding to direct M-M interactions and the appearance of bands due to a mixture of energy equivalent M-H-M and M-S interactions. The PE spectra also show a substantial rearrangement of M t(,2g)-like bands, which are usually considered M-CO (pi) bonding. It is the filled, antibonding M-S interaction with the t(,2g)-like orbitals, which corresponds to the band in the PE spectra between the M-M and the t(,2g)-like band. In the comparison with the PE spectrum of Os(,3)(CO)(,12), the major spectral changes for ((mu)-H)((mu)-X)Os(,3)(CO)(,10) and ((mu)-X)(,2)Os(,3)(CO)(,10) (X = Cl,Br,I) are the loss of intensity in the ionization band corresponding to direct Os-Os interactions and the appearance of bands due to M-X and/or M-H-M interactions. Shifts in the bands corresponding to the Os t(,2g)-like orbitals are observed. The MO calculations suggest that the t(,2g)-like Os(CO)(,3) orbitals interact with the bridging H and halogen atoms to produce these observed shifts. The MO calculations suggest that the only direct Os-Os bond in both series are the two (CO)(,4)Os-Os(CO)(,3) bonds and that the (CO)(,3)Os-Os(CO)(,3) interaction in the (HX) series is weakly bonding, while that in (X)(,2) series is weakly antibonding.
Description
Typescript (photocopy).Subject
Chemistry1983 Dissertation C524
Chemistry, Physical and theoretical
Molecular theory
Transition metals
Sulfur bonding
Collections
Citation
Chesky, Peter Thoma (1983). Photoelectron spectra and molecular orbital calculations of tricobalt alkylidyne and tri-cobalt, iron, ruthenium, and osmium sulfide nonacarbonyl and triosmium decacarbonyl clusters. Texas A&M University. Texas A&M University. Libraries. Available electronically from https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -551152.
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