Chemical Reactions of Hydride Ligands

On the other hand, [HRu6(CO)ig] shows a proton singlet at 5 16.43 ppm (the [(Ph3P)2N] salt in CD2CI2 at 40°C) or at S 16.49 ppm (the [Me4N] salt in THF-dg at 40 °C). However, the behavior of the interstitial H atom in the Ru cluster is different from that in the Co cluster. Neither excess KOH in methanol nor excess KH in THF could deprotonate the Ru cluster, a large excess of base causing decomposition with loss of the carbonyl IR spectrum.  

6 Metal Clusters Including an Interstitial light Atom Other than Hydrogen 

In recent years a great number of transition metal clusters containing an interstitial carbon atom has been prepared and now they constitute a growing field of metal carbide clusters . A far less number of nitride clusters and several compounds containing a naked P, As, or S atom embedded within metal clusters have been reported, such as 

There are, however, profound differences between the chemical behaviors of interstitial H and other atoms. In particular, no reaction analogous to the easy exchange of protons between the [HCo6(CO)i 5] anions and their surroundings is found in other interstitial complexes. Many more interstitial-hydride clusters would be desirable. 

As to the hydride-protonic preference of hydride compounds, those of the representative metals are hydridic, while those of the non-metals are protonic. The transition metals are in a boarderline situation. In general, hydrides which are good proton donors, are poor hydride donors. The best hydride donors are found to the left in the periodic table. Thus, the hydrides of Ti, Zr, and Hf show no acid properties, but behave as typical hydride ion donors.  

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