Distortion tetragonal

In fact the vast majority of 6-coordinate complexes are indeed octahedral or distorted octahedral. In addition to the twist distortion just considered distortions can be of two other types trigonal and tetragonal distortions which mean compression or elongation along a threefold and a fourfold axis of the octahedron respectively (Fig. 19.8). 

Figure 28.4 The anions of the chlorocomplex of stoichiometry, CsAuCl3, showing linearly coordinated Au and (4 + 2) tetragonally distorted, octahedral Au , i.e. Cs2[Au Cl2][Au CLt]-...

M3Ta02F4 and M3Nb02p4, where M = K, Rb, Cs, form ciystal structures similar to that of Rb3TiF6, which is described by Bode and Voss [189]. The structure of the compounds can be described as a tetragonally distorted cubic cell of the (NFL )3FeF6 type, the structure of which is described by Steward and Rockby [190]. 

Both compounds Mn304 (i.e., hausman-nite) and /-Mn203 crystallize with a tetragonally distorted spinel-type structure (see Fig. 17). 

Complexes of the divalent metals [M(ttcn)2]2+ undergo electrochemical oxidation to paramagnetic [M(ttcn)2]3+. Red [Pd(ttcn)2]3+ has a tetragonally distorted octahedral structure (d7, Jahn-Teller distortion) with Pd—S 2.356-2.369 A (equatorial) and 2.545 A (axial) in keeping with the ESR spectrum (gj = 2.049, gy = 2.009) which also displays 105Pd hfs. Similarly, electrochemical oxidation of the palladium(II) tacn complex (at a rather lower... 

Silver(II) fluoride AgF2 is a genuine silver(II) compound exhibiting Jahn-Teller tetragonal distortion (4F at 2.07 A 2F at 2.59 A) it exhibits a low... 

Environment Distorted tetrahedral Tetragonally distorted octahedron Strongly tetragonally distorted octahedron... 

A crystal-structure determination on [Ni(PhCH2CS2)2] showed evidence of a Ni-Ni bond (Ni—Ni distance, 256 pm) in a bridging, acetate-cage, binuclear complex (363). Each nickel atom is 5-coordinate and is in a tetragonally distorted, square-pyramid spectroscopic evidence for a Ni-Ni bond has been obtained (364). The polarized crystal spectra showed more bands than predicted for a mononuclear, diamagnetic, square-planar nickel(Il), and the spectra are indicative of substantial overlap of the d-orbitals between the two nickel atoms. The bis(dithiobenzation)nickeKII) complex was found to exhibit unusual spectrochemical behavior (365). 

The tetragonal distortion of the ccp structure also leads to the bcc structure. 

In the tetragonal transformation, the bcc structure is not the local maximum of the D parameter. Although the bcc stracture has a higher density if it is compressed along the tetragonal axis, many elements take this structure. On the other hand, the bet structure is the local maximum of the D parameter in the tetragonal distortion but no metal takes this structure. These results indicate that density is not an important factor for the choice of crystal stracture. 

A quantitative consideration on the origin of the EFG should be based on reliable results from molecular orbital or DPT calculations, as pointed out in detail in Chap. 5. For a qualitative discussion, however, it will suffice to use the easy-to-handle one-electron approximation of the crystal field model. In this framework, it is easy to realize that in nickel(II) complexes of Oh and symmetry and in tetragonally distorted octahedral nickel(II) complexes, no valence electron contribution to the EFG should be expected (cf. Fig. 7.7 and Table 4.2). A temperature-dependent valence electron contribution is to be expected in distorted tetrahedral nickel(n) complexes for tetragonal distortion, e.g., Fzz = (4/7)e(r )3 for com-... 

The high lability of cP [Cu(H20)6]2+ is coincident with the operation of a dynamic Jahn-Teller effect which causes its tetragonal distortion to randomly reorientate, or invert, about the x, y, and z axes very rapidly (Fig. 8) so that the lifetime of a given distortion, r, is much less than the lifetime of a given coordinated H20 molecule, THa0 (99,... 

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