Coordination spheres square pyramidal

Like their Fe analogs, Co porphyrins are aerobically stable. Co , being a if ion, favors a square pyramidal coordination sphere, and simple Co porph5Tins t)q)ically have fairly low affinity to axial hgands. As a result, many simple Co porphyrins are aerobically quite stable in the sohd state, but oxidize slowly if dissolved in a coordinating solvent. Simple Co porphyrins are typically stronger oxidants than the Fe ... 

It may be noted that, as expected, the equatorial distances are shorter than the axial. There is, of course, a close relationship between the square-pyramidal and the F-trigonalbipyramidal coordination sphere which are often difficult to discriminate when the tin-ligand bond distances in equatorial and axial positions do not differ significantly. 

The complexes of Tc(V) and Re(V) containing an M=0 core in the coordination sphere exhibit a square pyramidal structure, while those containing an 0=M=0 core are octahedral. 

Assume that the complex MLX2Y2 has a square-base pyramid structure with all ligands able to bond in all positions in the coordination sphere. How many isomers are possible ... 

The analogous cationic pyridylbis(oxazoline)-copper complexes exhibit square pyramidal geometries in the solid state. As in the bis(oxazoline) series, the triflate is closer to the metal than the SbF6 counterion (2.36 and 2.49 A vs 2.90 A). A single molecule of water is bound to the copper center in the triflate complex 267b, whereas the SbF6 complex 268b accommodates two water molecules in the coordination sphere, Fig. 24 (197). 

The yellow Co(II)-cyanide solid complex contains square-pyramidal five-coordinated Co(CN). The green ion in solution is possibly Co(CN)5H20 with very weak H2O coordination in the sixth axial position. It is an important inner-sphere reductant (Prob. 8 of Chap. 5, and Tables 5.3 and 5.7). Generally... 

The crystal structures of two isomeric 15-membered ring macrocycles containing the donor groups ON2S2 (70) and OS2N2 (71) have been determined as their silver thiocyanate salts.468 469 In the first, the coordination sphere around the Ag1 ion embedded in the cavity was approximately square pyramidal, with a weak interaction between the Ag ion and the O atom (Ag—O 288.3 pm). In the second, a square pyramidal structure was again obtained, although in this case there was no interaction with the O atom (Ag—O 371.9 pm). 

The synthesis of the X2M(Et2Dtc) complexes (X = Cl, Br, I M = As, Sb, Bi) is accomplished by the reaction of the M(Et2Dtc)3 complexes with MX3 in a 1 2 molar ratio in CHC13 (170). The structure of the Br2 As(Et2 Dtc) complex, which is monomeric and a nonelectrolyte in solution, in the solid state shows a loosely held centrosymmetric dimer with bridging bromide ions. The coordination geometry of the five-coordinate As(III) is intermediate between a square pyramid and a trigonal bipyramid, with a stereochemically active lone pair occupying a site of a distorted octahedral coordination sphere (Fig. 9). 

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