Pentanuclear clusters

As for tetranuclear clusters, pentanuclear transition metal clusters are only capable of partially encapsulating a main-group heteroatom. The c/o5o-pentanuclear cluster, the trigonal bipyramid, has an interstitial cavity of similar dimension to that of the tetrahedron, and must therefore open-up if it is to accommodate a semi-interstitial atom. The most commonly observed M5E clusters (E = main-group atom) adopt square based pyramidal structures, which can be derived from the trigonal bipyramid by M-M bond cleavage or can, alternatively, be viewed as /i/Jo-octahedral species (Scheme 2). 

There is only one example of a pentanuclear cluster, namely [Au5(dppm)3(dppm-H)](N03)2 (622), where the metal core adopts a spiked-tetrahedral geometry of gold atoms. 3... 

HEXACYANOMETALLATES AS TEMPLATES FOR DISCRETE PENTANUCLEAR AND HEPTANUCLEAR BIMETALLIC CLUSTERS... 

The cluster Ru6C(CO)17 was first prepared by pyrolysis of Ru3(CO)12 in nonane, a route which gave, at best, 19% yields.2 A later preparation, of which a modified version appears here, involves pyrolysis of RujtCO), 2 in hydrocarbon solvents under a moderate pressure of ethylene this gives much higher yields.3 The pentanuclear cluster Ru5C(CO)15 is prepared in > 90% yield by the carbonylation of Ru6C(CO)17.4... 

We describe herein its conversion into the tetranuclear cluster anion [Co3Ru(CO)12] itself leading to the pentanuclear species Co3RuCu(CH3CN)(CO)12 in good yield. 

A crystal structural analysis of the pentanuclear cluster l(MeZn)s(ButS)s] (115) has also been reported once again there is little evidence for direct Zn—Zn or S—S interactions.821 The structure is clearly based upon a square pyramid of zinc atoms. Further work in this area is surveyed in references 1468c-h. 

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