Metal cluster superconductors structure

The individual structural features of the high-tem-perature superconductors are found in other substances. A substance with alternating metal-salt layers is Ag2F, with sequence FAgAgFAgAgF . Resonance between a covalent bond and a no-bond is found in B (l =3,Z. 6) and in metals and organometallic clusters. Hyperelectronic-hypoelectronic electron transfer occurs... 

X-ray crystallography, 40 20-21 synthetic models, 40 23-48 xanthane oxidase, 40 21-23 chalcogenide halides, 23 370-377, 413 Chevrel phases, 23 376-377 metal-metal bonding, 23 330, 373 structural data, 23 373-376 as superconductors, 23 376 synthesis, 23 371-372 chloride, 46 4-24, 35-44 heterocations of, 9 290, 291 cluster compounds, 44 45-46 octahedral, 44 47-49, 53-63 electronic structure, 44 55-63 molecular structure, 44 53-54 synthesis, 44 47-49 rhomboidal, 44 75-82 solid-state clusters and, 44 66-72, 74-75, 80-82, 85-87 tetrahedral, 44 72-75 triangular, 44 82-87 cofactor, 40 2, 4-12 anaerobic isolation, 40 5 molybdopterin and, 40 4-8 reduced form, 40 12 synthesis, 40 8-12 xanthine oxidase, 45 60-63 complexes... 

We have utilized the embedded cluster DV scheme to study the electronic structure of the Y(Ni] IMI)B2C superconductors (M=Fe, Co, and Ru), with 71 atom variational clusters centered on the substitutional site [109] as shown in Fig. 13. Bonding within the RC plane is found to be highly ionic, while B-C and Ni-B bonding structures are analyzed as typically covalent. In addition, the strong overlap between atoms in the transition metal plane has typical metallic character. Thus the entire spectrum of chemical bonding including ionic, covalent, and metallic structures is found within this peculiar crystal structure. The Ni-B slab is found to be electron-rich, as the result of charge transfer from the RC planes. 

---