Macropolyhedral clusters

Metal atoms have fewer valence electrons than orbitals available for bonding and in this they resemble boron. The consequences of this idea are examined and it is shown that many metals with electronegativities in the range 1.6-2.4 (B = 2.0) can subrogate boron atoms as vertices in polyhedral clusters. Such metalloboranes are often much more stable than the parent boranes or borane anions. Not only can metals mimic boron in known cluster geometries but the flexibility thus introduced can lead to novel and previously unsuspected cluster geometries. The construction of macropolyhedral clusters containing 17-20 vertices is also described. 

The fused deltahedra need not be connected at four vertices, nor closed, nor of the same size. Thus, the number of fused compounds possible is large and the number of macropolyhedral clusters, as they are sometimes described, is growing. 

Even more complex macropolyhedral clusters can be obtained by appropriate thermolysis of [PtCTj -BgH 12)1-2] = PMe2Ph), e,g, the red 17-vertex [LP ii -... 

The first structurally characterized macropolyhedral carborane was 8-NC-9- BuNH2-rz //-9-C B17111 synthesized in 12% yield from HuNG and anti-B18H22 in benzene.664 The molecule can be viewed as a fusion of two 10-vertex nido-type clusters each sharing an edge on the open face with its partner (Figure 14). 

The oxaplatinaborane cluster [9,9-(PMe2Ph)2- rastructure analysis.158 An improved synthesis for oxa- 7spectroscopical data were discussed.1 - The macropolyhedral oxaborane [OB18H2i] was synthesized in moderate yield from [anti-B18H22] and the structure was crystallographically determined.163... 

MtfBy, M Bg, M B10, 3, 165 Group 10 complexes, 3, 167 lanthanide and actinide complexes, 3, 137 macropolyhedral metallaboranes, 3, 168 main group complexes, 3, 139 main group and lanthanide metal complexes, 3, 139 monoboron clusters, 3, 146... 

For a closo macropolyhedral borane cluster, the rule giving the required number of electron pairs is N = m + n. 

Macropolyhedral Boron-containing Cluster Chemistry. Further Progress Beyond the Icosahedron. July 1999... 

Some interesting clusters are known which combine the features of coinage metal clusters and metal carbonyls. Such heterobimetallic clusters can often be obtained from various reactions of Cu(I) or Ag(I) compounds with the Fe(CO)4 dianion. Thus, a series of clusters is known (Figure 14) having structures constructed from macro-polygonal or macropolyhedral networks with Fe-M -Fe edges (M = Cu, Ag) and typically Fe(CO)4 vertices such as the triangular cluster " Cu3(Fe(CO)4)3 , the but-... 

This approach has been particularly developed for application to macropolyhedral structures, clusters involving linked polyhedra, and many examples have been described." This approach is best illustrated by some examples. 

Macropolyhedral Condensed Boranes and Supra-icosahedral Clusters... 

Half-sandwich complexes have also been reported with macropolyhedral boranes, but the Ni-borane bonding in these complexes does not involve 7r-interactions. For instance, reacting nickelocene with anti- > zz results in the elimination of CpH and formation of the 19-vertex conjuncto- xxwQXm anions [Bi8H2oNiCp] , 231 subtle differences in the reaction conditions lead to the oxidation of 231 to give 232. Structural studies of these compounds have shown that their overall structures consist of two edge-fused cluster subunits (a 10-vertex and a ////To-10-vertex)... 

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