Square planar complexes structure

Structural assignments are now usually made on the basis of physicochemical techniques such as X-ray diffraction and spectroscopy. Another relatively simple technique involves measurements of dipole moments. The dipole moments of cis and trans isomers are often markedly different. This seems to be particularly true for certain square planar complexes, structure (45). 

Various bidentate ligands like dithiocarbamate afford monomeric square planar complexes specific examples are Pt(S2CNEt2)2 and Pt(Se2CNBu)2 (confirmed by X-ray). A similar structure is found for the dithiobenzoate Pd(S2CPh)2 one form of the dithioacetate is dimeric, a second form is a mixture of monomers and dimers. 

Spot tests, 1, 552 Square antiprisms dodecahedra, cubes and, 1, 84 eight-coordinate compounds, 1,83 repulsion energy coefficients, 1, 33, 34 Square planar complexes, 1,191, 204 structure, 1, 37 Square pyramids five-coordinate compounds, 1,39 repulsion energy coefficients. 1,34 Squares... 

In addition to the indications of an octahedral trans effect presented, there exists structural information in the form of bond lengths and spectral data similar to that described earlier for square planar complexes. Although the trans effect in octahedral complexes is not the dominant influence that it is in square planar complexes, there is no doubt that there is such an effect. 

In order to give the usual overview of nickel complexes at increasing coordination numbers we begin with the usual square planar complexes of the Schiff bases salen and saloph.149,150 As an example, Figure 98 shows the molecular structure of [Nin(salen)]. 

Based on these findings, new pentacoordinated Ir complexes [lr(cod) (S)-(+)-(NNR )1] were synthesized and characterized also by X-ray crystal structure determination by the same authors (NNR = 2-pyridinal-l-phenyhethylimine, PPEI, 77a 2-acetylpyridine-l-phenylethylimine, APPEl, 77b Scheme 4.32). The complexes were tested in the ATH of ketones in isopropanol and the data compared with results obtained using the corresponding square planar complexes [Ir(cod) (R) -(-)PPE1 ]C104 (76d) [67]. 

Square-planar complexes of platinum(II) and palladium(II) have been known for a long time the comparatively simple unit cells of compounds such as K2PdCl4, K2PtCl4, and Pd(NH3)4Cl2H20 led to early elucidation of the structures (257) and they all contain square-planar ions. The simple halides PdCl2 and Pt,Cl2 (71) consist of chains in which the metal is bonded from the corners of a square. Nickel chloride, on the other hand, has a layer lattice in which the nickel is octahedrally coordinated, and in the halide complexes the coordination is tetrahedral, as described in Section IV,B. 

The Ni—N bond distances, N-N bite distances, and N-M-N bite angles of Ni(II) macrocyclic complexes depend on the coordination number of the metal ion and the type of macrocycle. These structural parameters influence the electronic spectra and the electrochemical data. In general, Ni—N bond distances of square-planar complexes are shorter than those of the octahedral complexes because of the absence of electrons in dx2 . Furthermore, as the Ni—N bond distance in-... 

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