Molecular geometry pentagonal bipyramidal

Four crystal modifications of [U02(acac)2(H20)] have been reported in the /3 form the molecular geometry is a pentagonal bipyramid with four oxygen atoms from the acac groups and one from the water molecule in the equatorial plane.225... 

Pentavalent. Protactinium is known to bind sulfate in solutions of H2SO4 however, very limited data are available on the molecular species. Sulfate complexes with the general formula of Np02(S04) " (n = 1 3) have been reported. In most of these complexes, the Np is found in a seven-coordinate pentagonal bipyramid geometry. 

For tin(IV), the most frequent coordination geometries are based on tetrahedral, trigonal-bipyramidal, octahedral, and pentagonal-bipyramidal polyhedra." In organometallic tin(IV) complexes there is a tendency for the tin atoms to enhance their coordination number either via intra-molecular coordination or inter-molecular association. The final coordination number depends strongly on the number of organic substituents attached to the tin atom and the nature of the donor atoms of the ligands. ... 

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