Cluster pentanuclear clusters

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... 

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... 

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. 

Similarly, thermolysis of the triosmium NHC cluster Os3(ImMe2)(CO)n affords the edge-bridged (24, M — Os) and derivatives (21, M = Os), resulting from sequential oxidative addition of one and two C-H bonds, respectively the ruthenium analogue 21 is prepared from a similar reaction, which affords as minor products the pentanuclear clusters 25 and 26 containing p4-q2-CO ligands.29... 

The reactions of HNCC with Hj, I2, or HX (X = Cl, Br, I, SEt, SH, SeH) to give products of unchanged nuclearity may result in the oxidative addition of these molecules to M—M bonds. For example, the pentanuclear clusters... 

Bonding mode M18 is found in the pentanuclear cluster Ru5(CO)13(p-PPh2)(C=CPh) (431), shown in Fig. 37. The alkyne-derived ligand which may be considered to be an acetylide is formally a bonded to two adjacent Ru atoms of the rectangle and involved in a n interaction with the other two the acetylide C-C bond length is 1.34(1) A. The acetylide... 

Despite the interest in group 2 bis(alkoxides) and bis(/3-diketonates) as precursors to metal oxides via CVD routes, systematic studies that correlate their structure and volatility still are few. The solid-state structures of many bis(alkoxides) used for CVD work are not known, and the identity of the materials may vary greatly depending on then-mode of preparation. As shown above, the widely used bis(/3-diketonate) derivative Ba(tmhd)2 for example, has that formula only if prepared under rigorously anhydrous conditions in the presence of moisture the pentanuclear cluster Ba5(tmhd)9(H20)3(OH) can form. Such uncertainties make the identification of trends in volatilities difficult. 

Scheme 11 illustrates the geometrical architectures assumed by the pentanuclear cluster compounds examined from an electrochemical viewpoint. 

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