1.4.7- Tris hexaamines

The [Co(phen)3]3+ complex is photoactive and a powerful oxidant in its excited state. The ion has no H-bonding groups and hence is considerably more hydrophobic1279 than hexaamine relatives. These properties have proven particularly useful. Aryl and alkyl substituted [Co(phen)3]3+ complexes have received a great deal of attention due to their ability to intercalate within the helical structure of DNA through a combination of electrostatic and hydrophobic forces. The chirality of the tris-chelate complex is crucial in determining the degree of association between the complex and... 

Multiple arylations of polybromobenzenes have also been conducted to generate electron-rich arylamines. Tris(4-bromophenyl)amine and 1,3,5-tribromobenzene both react cleanly with N-aryl piperazines with either P(o-tolyl)3 or BINAP-ligated catalysts to form hexaamine products [130]. Reactions of other polyhalogenated arenes have also been reported [189]. 

The two cobalt(III) hexaamines with relatively short metal-donor distances considered here are [Co(7ra s-diammac)]3+ trans-diammac is trans-1,4,8,11 -tetraazacy-clotetradecane-6,13-diamine, see Fig. 17.11.1) and [Co(trap)2]3+ (trap is 1,2,3-tri-aminopropane, see Fig. 17.11.2). There are three conformers of [Co(taa s-di-ammac)]3+ (35, 51,15 where 5 and 1 refer to the conformation of the five-mem-bered chelate rings in the complex - see also Section 17.3). The A<5-conformer is the most stable form and has been characterized by an X-ray diffraction study. 15-[Co(fra .v-diammac)]3+ has very short Co-N bonds (1.937A (four equatorial bonds), 1.946 A (two axial bonds)), and the experimentally determined high ligand field and the strongly negative redox potential confirm that these structural features are conserved in solution190 231,2811. 

The vNiN vibrations were assigned in 2,6-diacetylpyridine dioxime at 416, 341 and 276 cm and at 370 and 265 cm in hexaamine complexes, at 410 and 334 cm in triethylendiamine derivatives, around 240 cm" in pyridine derivatives and in imidazol complexes between 325 and 210cm"Gobemado-Mitre et al attributed the vCuN mode in copper complex of naphthalocya-nine to those bands observed at 341 and 221 cm" In Cu(II) tri-azamacrocycles it has been proposed the bands at 383 and 314 cm" as due to vCuN. This mode was observed in copper complexes of cyclam at 437 cm" and in Cu(II) hexaazacyclophane at 390 and 280 cm" In phenantroline Cu(II) complexes the vCuN vibration was identified with the bands at 300 and 430 cm" In the case of the Zn complexes, some tetraamine derivatives display the vZnN band at 432cm" and in triethylendiamine complexes were observed at 405 and 291 cm" in imidazole complexes the vZnN mode was assigned to the bands between 325 and 210 cm" The vZnN mode of bis(phenylhydrazine)-l, 10-phenantroline Zn(II) was attributed to the bands at 376 and 267cm" ... 

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