Dodecanuclear clusters

Mixed O, N donor molecules are truly extensive and structurally diverse, and only a few selected examples will be presented. In line with other 2-substituted pyridine analogs reported in this chapter, it is worthwhile noting the chemistry of 2-pyridone (or 2-hydroxypyridine, Hopy), which can form O-bonded monodentate complexes such as Co(Hopy)4(N03)2, but as the monoanion is an effective chelate ligand, forming Co(opy)2 and Co(bpy)(opy)2 compounds.454 An unusual solid state melt reaction with Co(OAc)2 yields the dodecanuclear cluster Co12 (OH)6(OAc)6(opy )12.455... 

It is possible to use ancillary ligands in addition to phosphonic acids in building up nanosized cluster compounds of late transition metal ions. Thus, the reaction of CuCl2 with tert-butylphosphonic acid in the presence of 3,5-dimethylpyrazole affords a dodecanuclear copper phosphonate with an interesting cage structure,3 Similarly, large vanadium phosphonate clusters with up to 18 vanadium atoms have been assembled from phosphonic acids.35... 

Figure 6.31 The structures of (a) dodeca-, (b) pentadeca-, and (c) octadeca-nuclear clusters templated by two IX4-H ions, a X5-X (X = C1, Br) ion, and Xe p r r r r r COj , respectively. Formal assembly of a 60-metal hydroxide complex featuring 26 vertex-sharing [Ln4(ti3-OH)4] cubane units. These cubane building blocks form six dodecanuclear squares and eight octadecanuclear hexagons [102]. (Redrawn from X. Kong et al, A chiral 60-metal sodaUte cage featuring 26 vertex-sharing [Er4(p.3-OH)4] cubanes, Journal of the American Chemical Society, 131, 6918-6919, 2009.)...

Andrews, P.C., Beck, T., Forsyth, C.M., Fraser, B.H., Junk, PC., Massi, M. et al. (2007) Templated assembly of a p-g-COj" dodecanuclear lanthanum dibenzoylmethanide hydroxide cluster with concomitant formation of phenylglyoxylate. Dalton Transactions, 5651-5654. 

The first, and most studied family of SMMs are the dodecanuclear complexes of general formifla [Mni20i2(02CR)i6(H20)xl (n = 0, 1, 2 x = 3, 4). Of the more than 100 different Mn clusters known to display SMM behaviour more than half the members belong to the [Mn j family. This class of compounds retains the record for the largest energy barrier for the reorientation of the magnetisation and this, combined with the fact that [Mn OAc] is the prototype SMM and is extremely easy to make, has led to numerous... 

S-5 Complex 154 was the first example of a dodecanuclear heterobimetallic cage cluster with a central S ligand. Three Ag—Ag pairs are bound to the central S atom in a propeller-like disposition and three M—M pairs are bound to the Ag—Ag pairs through SCH2CH2S... 

Using a lanthanide ion of intermediate size, for example Nd(III), whose preferred coordination number is 9, an interesting and unexpected dodecanuclear complex [Na(H20)2]4[Ndi2(/t3-0H)i6(EDTA)g] was obtained (Figure 93). Its core structure is the same as for the dodecanuclear cluster templated by iodo ligands in the aforementioned Tyr-R coordination studies (Figure 88), but no iodide was employed in the present case. One salient feature of this cluster is the two t) es of Nd... 

The pyrolysis of 2, even if conducted under relatively moderate conditions (in MeOH, MeCN, /-PrOH or DGM, not exceeding 80 °C), never gives evidence for an octahedral 86 CVE species analogous to the cobalt one. Indeed, the first IR detectable species in solution have been all identified as dodecanuclear clusters, namely... 

Toma, H.E., K. Araki, and E.O. Silva (1998). Synthesis and characterization of a novel dodecanuclear porphyrin ruthenium cluster. Monats. Chem. 129, 975-984. 

Liu X, Huang K-L (2009) A 12-connected dodecanuclear copper cluster with yellow luminescence. Inorg Chem 48 8653-8655... 

---