Ionic hydride definition

The hydrides HM(PF3)4, M = Co, Rh, Ir, possess a structure simUar to that of HCo(CO)4. In C3v skeletal symmetry the filled metal orbitals are of symmetry e(2), the Rh-H a bond transforms as a, and the metal-phosphorus a bonds span the irreducible representations a,(2) + e. Three low-energy peaks (Table XXIX) (169, 227) have been detected in the UPS of HCo(PF3)4, and overlapping of ionization occurs with the Rh and Ir compounds (Fig. 28). While the assignments cannot be regarded as definitive at the present time, the first two peaks in the UPS of HCo(PF3)4 probably correspond to the two 2E ionic states of predominant metal character. 

Since in electron spectroscopy the time scale of the measured ionization processes is on the order of 10 16 sec, definite ionic species are characterized, regardless on their possible intra- and intermolecular interactions (e. g., Wagner-Meerwein rearrangements, hydride shifts, proton exchange, etc.). Thus, electron spectroscopy gives an undisputible, direct answer to the long debated question of the non-classical nature of the norbornyl cation independent of any possible equilibration process. 

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