2,2 ,2"-Tris amine. ligand

The formation of relatively stable species of the type (ArN)3N Mo N = N—MoN(NAr)3], in which further reduction of the N2 moiety is not very favored, can be prevented by the use of larger (ArN)3N triamido ligands. This led to the development of tris(amido)amine ligands... 

Figure 5 General formula of the tris(l-pyrazolylethyl)amine ligands...

Chromium(II) complexes of bipyridyls, terpyridyl and the phenanthrolines have been discussed in Section 35.2.2.1. Complexes of the ligands 2-aminomethylpyridine (pic, 2-picolyl-amine) and 8-aminoquinoline (amq), which have one heterocyclic and one amino nitrogen donor atom, have been prepared by methods similar to those in Scheme 10. The bis(amine) complexes are typical high-spin, distorted octahedral complexes, and the mono(amine) complexes, from their antiferromagnetic behaviour and reflectance spectra, are six-coordinate, halide-bridged polymers (Table 15).103 No tris(amine) complexes could be prepared so the attempt to find spin isomeric systems in octahedral chromium(II) systems was unsuccessful ([Cr(en)3]X2 are high-spin and [Cr(bipy)3]X3 and [CrX2(bipy)2] low-spin). 

There are certain classes of coordination complexes that are particularly well characterized with amine ligands. Among these are the /r-peroxo and /r-superoxo Co111 complexes with general formula (N5)Co(02)Co(N5)"+, where Ns can be a variety of amine nitrogen donors3 42 and the tri-/r-hydroxo Co111 systems (N3)Co(OH)3Co(N3)3+.43... 

All the linear triamines (27)-(31) are commerically available and there are others, such as 6,6-tri, which, as yet, do not appear to have been used in the preparation of coordination complexes. These linear polyamine ligands can coordinate in either meridional or facial topology and both bis(tri-amine) and mono(triamine) complexes are possible for octahedral central metal ions. 

The topology of the complexes of these ligands is discussed extensively in a review [28 5e] and in a monograph [263]. In addition to the ligands described above, the aniline derivative may participate as tri-, tetra-, and penta-amine ligands, as for example 181 and 182 [285e] ... 

Markus Albrecht and co-workers synthesised three M4L4 tetrahedra based on different C3-symmetric imine type ligands. The ligands are shown in Fig. 16. For the formation of these ligands, 2,3-dihydroxybenzaldehyde was reacted with the product of the reduction of the corresponding trinitro derivative (L21) or with a tris-amine derivative (L22, L23) [30, 135-141]. 

Fig. 16 Structures of the redox catalyst tris(l,10-phenanthroline-5,6-dione) ruthenium(II) perchlorate 1 and the mixed ligand system consisting of l,10-phenanthroline-5,6-dione and one N,N, A-tris(aminoethyl)amine ligand 2...

Luminescence of the Eu + complex of the tetradentate tris(2-pyridylmethyl)amine ligand shown in Figure 5.12 (R = Me) shows a particular sensitivity for nitrate (over other ions such as chloride, sulfate, and acetate), greatest enhancement of the luminescence spectrum being for the hypersensitive Dq ->- F2 transition at 618 nm, as might be expected (see T. Yamada, S. Shinoda, and H. Tsukube, Chem. Commun., 2002, 218). 

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