Metal-core, structure

Metastable solutions of GaX (X = C1, Br) as well as conventionally prepared Gal react with lithium or sodium organometallics in standard salt metathesis reactions with formation of M2R4 (Section 3.07.4.1) as well as neutral and anionic clusters of the type MnRm]x m > n) (chapter 4.1). Moreover, metalloid clusters [MnRm]x (m < n), which feature different types of metallic core structures, have been obtained. Their formation strongly depends on the reaction conditions, in particular the reaction temperature, and the (donor) solvent. 

Fig. 30. Metal core structure of the anions [Rh Pti/is-NK -COJ fCO),]3- (126) [Reproduced with permission from Martinengo el al. (176)] and [Rh1HPt4(/j-CO)21(CO)l4]4 (Pt atoms shaded).

A few illustrative examples dealing with bimetallic cluster compounds will now be presented. For example, mixed cluster compounds [MjRu -CO CO qCPPI J where M = Cu, Ag, and Au have been prepared and structurally characterized. ) Metal core structures consist of a Ru4 tetrahedron with M-PPh3 groups capping two... 

The NMR spectra of the cluster suggest that two skeletal isomers are present in solution at ambient temperature. It seems likely that these two isomers exhibit metal core structures similar to those which the two isomeric forms of the very closely related cluster [Au2Re2H6(PMe2Ph)4(PPh3)2] are thought to adopt (Fig. 11) (52). 

The clusters [Cu2Ru4(/i-H)2(CO)12 P(CHMe2)3 2], [Au2Ru6C(CO)16-(PEt3)2], and [Au2Ru5M(CO)17(PEt3)2] (M = Cr, Mo, or W) exhibit only one metal core structure in the solid state, but two skeletal isomers exist in solution at low temperatures. Interestingly, at ambient temperature in... 

The cluster is thought to exhibit a similar metal core structure to that adopted by [Au3Ru3-(ju3-C12H15)(CO)g(PPh3)3](2S)1 although the IR spectra of the two compounds differ significantly. 

Cluster Ground state metal core structure 1 Number of structurally inequivalent CuL (L = two-electron donor ligand) units NMR evidence for dynamic behavior at ambient temperature Low temperature NMR spectrum consistent with ground state structure observed Ref. 

The solid state metal core structure is given, unless otherwise stated. 

Many dusters incorporate heteroatoms such as H, C, N, or even As, Sb, P, S, Ge, etc. inside their metallic cores (see Chapter 3.2). [189] The metal core structure usually forms a cavity in which the heteroatom is accomodated. The metallic core can be fundamentally cubic or pentagonal. The number of interstitial atoms embedded within the metal core depends on the geometry and the dimendons of the cluster. In some cases a small molecule is encapsulated in the metal duster, for example, in the dusters [Co6Ni2C2(CO)i4p [190] and [Nii6(C2)2(CO)23] " [191]... 

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