Dodecahedral geometries

Uranium tetrachloride [10026-10-5], UCl, has been prepared by several methods. The first method, which is probably the best, involves the reduction/chlorination of UO [1344-58-7] with boiling hexachloropropene. The second consists of heating UO2 [1344-57-6] under flowing CCl or SOCI2. The stmcture of the dark green tetrachloride is identical to that of Th, Pa, and Np, which all show a dodecahedral geometry of the chlorine atoms about a central actinide metal atom. The tetrachloride is soluble in H2O, alcohol, and acetic acid, but insoluble in ether, and chloroform. Industrially the tetrachloride has been used as a charge for calutrons. 

Crown ether complexes of bismuth nitrate were prepared by reacting Bi(N03)3 5H20 in 3 1 MeCN MeOH with a stoichiometric amount of the crown ether (101). Bi(N03)3(12-croum-4) has bismuth in a 10-coordinate Cs 4A,6B-expanded dodecahedral geometry 31, in which all four ether oxygen atoms are bound to the bismuth center... 

Dodecahedral geometry, for metal coordination numbers, 7 574, 575t Dodecanedioic acid, 4 374 Dodecanoic acid, physical properties, 5 29t 1-Dodecanol, physical properties of, 2 3t n-Dodecanol... 

The tetrakis- 8-diketonate complexes of the lanthanides constitute an important stereoisomer in the dodecahedral geometry. The four diketonate ligands are found to span the four g-edges of the dodecahedron (Fig. 22) (146, 147). In other do-... 

Diperoxo Nb(V) complexes have been synthesized and, in some cases, strnctnrally characterized in the presence of oxidized polyaminocarboxylato ligands . With this metal, the distorted dodecahedral geometry is common for the few species known 18 is an example. 

Tetrakis O, O -dialkylthiophosphates have been obtained for niobium starting from oxidation states +V or +IV (Table 40). These chelates display a distorted dodecahedral geometry in the solid (X-ray) as well as in solution (ESR).561 An unusual cation, [ Nb(Cp)2 2(PS4)]+, in which a PS4 moiety is doubly bridging the terminal NbCp2 units, has been obtained from [NbCl2(Cp)2] and P4Si0. The metal has a distorted tetrahedral environment of approximate symmetry, while symmetry at phosphorus is reduced to C. ... 

The tantalum(IV) hydrides [TaH2Cl2(PMe3)4] (51) and [TaH2Cl2(dmpe)2] (50) were characterized by low temperature X-ray crystallography. SSS,69Z Complex (51) adopts a distorted dodecahedral geometry in the solid state, while (50) is better described as a distorted square antiprismatic complex. The hydrogen atoms have been located. 

A number of isocyanide complexes, [Mo(CN)4(CNR)4] (R = Me, Pr, Bu allyl, NCPh2), have been made by the action of RI on Ag4[Mo(CN)8]. The crystal structure of [Mo(CN)4(CNMe)4] shows a dodecahedral geometry, with the CN- ligands at 2.177(8) A and the MeNC ligands at 2.148(8) A from the molybdenum.207 Both 13C NMR and vibrational spectroscopy indicate that only one isomer is present in solution. 

Although very high coordination numbers are rare for iron(II), eight-coordination is well characterized in the red-orange high-spin complex with 1,8-naphthyridine, [Fe(naph)4]2+, which in the perchlorate salt has a distorted dodecahedral geometry.40 41 Seven-coordination is more common than eight-coordination, and is known in several macrocyclic complexes.42... 

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