1. Pecoraro, V. L.; Stemmler, A. J.; Gibney, B. R.; Bodwin, J. J.; Wang, H.; Kampf, J. W.; Barwinski, A.Progress in Inorganic Chemistry; Karlin, K. D., Ed.; John Wiley & Sons: New York, 1997; Vol. 45, p 83.
2. Synthesis and Crystal Structure of the First Inverse 12-Metallacrown-4
3. Structural characterization of [VO(salicylhydroximate)(CH3OH)]3: Applications to the biological chemistry of vanadium(V)
4. Development of Metallacrown Ethers: A New Class of Metal Clusters
5. Metallacrown Nomenclature. The nomenclature for metallacrowns is as follows: M‘mAa[X-MCMn+H(Z)-Y], whereXandYindicate ring size and number of oxygen donor atoms, MC specifies a metallacrown, M andn+ are the ring metal and its oxidation state, H is the identity of the remaining heteroatom bridge, and (Z) is an abbreviation for the organic ligand containing the NO functionality. There are m‘ captured metals (M‘) and a bridging anion (A) bound to the ring oxygens and metals, respectively. A metal-encapsulated metallacrown is represented by [Ni(AcO)2][12-MCNi(II)N(shi)2(pko)2-4]. This molecule has the core structure of 12-crown-4 with the carbon atoms replaced by Ni(II) and N atoms throughout the ring. The trianion of salicylhydroxamic acid (shi3-) confers stability to the ring. A single Ni(II) is captured by the hydroxamate oxygens, and there are two bridging acetates linking two ring metals to the captured metal. While not discussed here, a full treatment of additional descriptors of chirality for the ring and captured metal ions are given n refs 1 and 4.