Fluxionality, collective oscillations and the low-energy spectra of transition metal cluster carbonyls

Abstract

Some spectroscopic consequences of Johnson's hard sphere structural model for polynuclear transition metal carbonyls are investigated. The fluxional motions of the carbonyl ligands are interpreted as collective surface oscillations and the liquid droplet model in nuclear physics is used to calculate the excitation spectrum of these collective modes. According to this conjecture metal cluster carbonyls should have distinctive spectra in the range 10 cm^-1–100 cm^-1, this being the energy régime where the Born-Oppenheimer rigid-rotor, small-amplitude vibrator model breaks down and highly excited rigid rotor rotational excitations begin to couple strongly with vibrational excitations so as to produce collective excitations that classically are interpretable as large amplitude concerted motions of the ligands about the metal cluster core.

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Notes on contributors

R.G. Woolley

SRC Advanced Fellow