Metal clusters electron counting procedures

The foregoing examples show the relevance to metal-carbonyl cluster chemistry of the borane-oarborane structural and bonding pattern. Its relevance to other areas of chemistry may be explored readily using a systematic skeletal electron-counting procedure (161, 201). 

For mixed main group-transition element clusters containing but one transition element, modifying the above electron-counting procedure to include the 6 nonbonding electron pairs on the transition metal has been advocated (128) as a way of bringing the electron count into line... 

For a description of the electron-counting procedure as applied to metal clusters, see Ref 37.) The paramagnetism of the nickel cluster, in principle, could be detected directly by neutron diffraction with a polarized beam and an external magnetic field. However, such measurements were not undertaken, and the effects of paramagnetism on the observed diffraction intensities, that are small in the present experiment, were ignored. 

A division into Wade s systems, belonging the 2n + 2 rule and non-Wade s clusters has been discussed by Struchkov125b with the aim to extend the electron counting procedure to conjuncto-clusters. An additional concept of structural rules for transition metal clusters has recently been presented by Xu125. Lauher126,127 used extended... 

A classical example of correlation of structure with valence electron count of transition-metal clusters is shown in Fig. 19.4.2. There the structures of a series of osmium clusters are systematized by applying the capping and decapping procedures. 

A convenient procedure for electron counting in metal clusters is achieved by making a balance between the number of electrons in the system and the atomic orbitals to which they can be assigned. 

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