Cobalt, tris complexes structure

Cobalt, tris(l,2-propanediamine)-complexes structure, 1, 25 conformation, 1,25 nomenclature, 1, 129 stereonotation, 1,129... 

It has been shown that mononuclear cobalt superoxo complexes react with 2,4,6-tri-t-butyl-phenol. The anion [Co(CN)5(02)]3 acts as a base in the oxidation of the phenol. The neutral complex Co(salptr)(Oz) forms a peroxy adduct with 2,4,6-tri-t-butylphenol. An X-ray study on this adduct has revealed the structure shown in (10).m... 

Figure 7-2. A representation of the cobalt(m) complex 7.1 formed from the reaction of tris(di-methylglyoximato)cobaltate(in) with BF3 Et20. The three-dimensional structure observed in the crystal lattice of the tetrafluoroborate salt is also shown. The final view emphasises that the co-ordination geometry about the metal centre is distorted towards trigonal prismatic in these complexes.

FIGURE 9-20 The Cotton Effect in ORD and CD, (a) Idealized optical rotatory dispersion (ORD) and circular dichroism (CD) curves at an absorption peak, with a positive Cotton effect, (b) Structures of tris-(S-alaninato) cobalt(IIl) complexes, (c) Absorption and circular dichroism spectra of the compounds in (b). (Data and structures in (b) adapted with permission from R. G. Denning and T. S. Piper, Inorg. Chem., 1966, 5, 1056. 1966 American Chemical Society. Curves in (c) adapted with permission from J. Pujita and Y. Shimura, Optical Rotatory Dispersion and Circular Dichroism, in K. Nakamoto and P. J. McCarthy, eds.. Spectroscopy and Structure of Metal Chelate Compounds, John Wiley Sons Inc., New York, 1968, p. 193. 1968 John Wiley Sons, Inc. Reprinted by permission of John Wiley Sons, Inc.)... 

A great number of papers deal with the stereospecificity of the interaction of optically active [CoNe] + complex cations with optically active anions and the stereospecificity depending on the structures of these cations and anions. A variety of tris-diamine cobalt(HI) complexes with different structures, clathrochelates with diverse capping groups, and the semiclathrochelate [Co(sen)]3+ cation have been investigated. Many investigators have employed d- and Z-tart -[Sb2(d-,Z-tart)2]2, and [As2(d-,Z-tart)2] dianions as optically active reagents [307, 310-312]. 

The fell values for most macrobicyclic tris-dioximates and Ne-nSn-sarcophaginates (n = 2, 3) increase with decreasing E values. The cobalt Se-sarcophaginates and boron-capped tris-benzyldioximates drop out of linear correlation for both low-spin cobalt(II) and cobalt(III) complexes. The lack of this correlation in the first case may be attributed to the absence of structural changes in passing from the cobalt(III) complex to the cobalt(II) complex. In the second case, an increased fen value may be attributed to the special rigidity of hexaphenyl-substituted cobalt clathrochelates. 

The next example (see Figure 13) is the tris(ethylenedia= mine)cobalt(III) complex. The site symmetry term is octahedral, six coordinate or OC-6, and the configuration number is 11. The nitrogen atoms are all equivalent, and the chelation defines a right-handed or A helix to give the complete notation 0C-6-11-A. I have indicated the primes on the chelating ligands in this structure to illustrate how to determine the... 

A hydroxy group attached to a metal chelate ring would also be expected to undergo ready acylation. An investigation of the cobalt(III) complex of AT-hydroxyethylethylenediamine (structure XXVI) gave the unexpected result that the tris complex was extremely stable and that the hydroxy groups in the complex were quite unreactive (111). 

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