Pentametallic clusters

Figure 8 ORTEP diagram of the pentametallic cluster 149. Reproduced from Richards, A. F. Brynda, M. Olmstead, M. M. Power, P. P. Organometallics 2004, 23, 2841-2844.

In the above compounds, the structural motif is the M4S4 cubane, but these closed structures will not incorporate three //2-sulfide bridges easily. A different self-assembly route leads to MoFe clusters that have a different composition but do contain a sulfur-voided cubane held by three //2-sulfides. The clusters MFe4S6Ls are shown as (15). Their Fe4(//3-S)3(//2-S)3 portions structurally resemble the part of the FeMoco farthest from molybdenum. These pentametallic clusters have been used to calibrate Fe EXAFS of the FeMoco. Another important aspect of these clusters is that three iron atoms have trigonal pyramidal geometry like the belt iron atoms of the FeMoco, with three sulfides in the basal positions and a phosphine in the axial position. A series of basket ... 

Reduction of bulky organohalogermylenes leads to the formation of pentametallic germanium clusters 149 and 150 (Equations (260) and (261), respectively).322 The structure of 149 is shown in Figure 8, and selected structural data are collected in Table 32. The five germanium atoms are held together by six two-center, two-electron bonds, and a lone pair resides on the unsubstituted Ge(5) atom. 

Ytterbium luminescence has also been seen for a nonametallic cluster assembled from hexylsalicylate (hesa) and with overall formula H i o Yb<)(hcsa) i e (/x-0)i o (NO3). The cluster has two fused square-pyramidal pentametallic units assembled via an apical metal ion. The two square pyramids are twisted 45° and the cluster core is stabilized by hydroxide bridges. The luminescence decay of the Ybm cluster is bi-exponential, with lifetimes of 0.2 and 0.6 ps, reflecting the two types of cations (Manseki et al., 2006). 

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