Photoelectron spectra of some silyl and germyl transition-metal carbonyls and related species

Abstract

The He l (21·22 eV) photoelectron spectra of six silyl and germyl (M¹H₃) derivatives of Mn, Re, and Co (M²) carbonyls show bands attributable to (a) transition-metal unshared d-electrons (M²n′d) in the range 8–10 eV binding energy; (b) to the M¹H σ-bonding levels derived from M¹np orbitals (11–12 eV), and (c) the carbonyl groups (13–19 eV). Correlation with related hydride and methyl derivatives, where known, suggests that the M¹M²σ-bonding level gives rise to a band in the 9–10 eV region, where it is obscured by the M²n′d bands. No evidence for any π-interaction between the M²n′d orbitals and the M¹H₃ group is observed; it is concluded that the observed shifts in M²n′d reflect the varying σ-acceptor powers of the M¹H₃ groups, methyl being a poorer σ-acceptor than silyl or germyl.