PBP geometry

In these structures, the cupf assumes its typical chelating coordination pattern and is nearly symmetrically bound to the [Me2Sn(IV)] center. In complex (4) a pentagonal bypiramidal (PBP) geometry containing C2SnOs moiety was found by XRD method. The Bu2Sn(IV)-cup complex proved to be... 

Bis(dicyclohexylammonium) bis(2,6-pyridinedicarboxylato)dibutylstannate is concluded to have sevenfold coordination at the Sn on the basis of its Sn CP/ MAS NMR chemical shift ((5 = —424.9 ppm). The assignment has been corroborated by crystal structure determination of its monohydrate, in which the Sn atom has frflMS-C2SnN04 PBP geometry (Sn-C = 204.0,206.7pm, C-Sn-C = 168.9°). One 2,6-pyiidinedicarboxylato group chelates to the Sn atom (Sn-O = 223.4,226.0 pm Sn-N = 227.9 pm), whereas the other binds through only one carboxyl end (Sn-O = 241.6, 244.1pm). The anhydrous compound displays higher in vitro antitumor activity than those of cisplatin and carboplatin (Table 7). ... 

An interesting structural feature of [Fe(dapsox)(H20)2l is its pentagonal-bipyramidal (PBP) geometry with kinetically labile solvent molecules coordinated in the axial positions and the completely planar pentadentate chelate in the equatorial plane, which generally facilitates easy access of nucleophiles to the metal center without any steric hindrance above and below the pentadentate plane. 

The remaining two hepta-coordinate structures of Fe(III) are p-oxo dimers. The first of them [(H20)BFe-0-FeB(H20)](C104)4 includes a macrocyclic ligand (Table I), and the other one [Fe20(N03)4(bpy)2] (bpy = 2,2 -bipyridine), bidentate ligands (100,101). The PBP geometry of the p-oxo-diiron(III) complexes is unusual since these complexes have square-pyramidal or octahedral structures with the exception of the above-mentioned two complexes. 

A schematic presentation of the complex structures synthesized is presented in Scheme 11. The stability of complexes with PBP geometry of ions with spherically symmetrical electron distribution has been observed earlier (23,45), as in the case of high-spin Fe(III) 9 and... 

The first example of a PBP geometry in which a bidentate ligand spans one of the pentagonal edges is furnished by the structure of [W(CO)3I2(Ph2PCH2PPh2)].325... 

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