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Macrocyclic complexes of transition and inner-transition metal ions in identical ligand framework: Synthesis of cobalt(II), nickel(II), copper(II), lanthanide(III), and uranyl(VI) complexes of a 16-membered tetraaza macrocycle
| Content Provider | Semantic Scholar |
|---|---|
| Author | Alexander, V. Furduev Angelo, A. N. Paul |
| Copyright Year | 1996 |
| Abstract | The [16]-membered tetraaza macrocycle 2,3:6, 7:10, 1 !: 14,15-tetrabenzo-l,4,9,12tetraazacyclohexadeca-4,8,12,16-tetraene (L4) has been synthesized in the free form by the metal template Schiff base condensation. The formation of the metal free '2 + 2' macrocycle as the sole product by the metal template reaction is referred to as 'pseudocoordination template effect'. Our results suggest that free macrocycle can be prepared by the metal template method. Pseudooctahedral cobalt(II) complexes [Co(L4)X 2 ] (X = CI-, NCS-, or NO~-), nickel(II) complexes [Ni(L4)X2 ] (X = CIor NO~-), square pyramidal copper(II) complexes [Cu(L4)X ] X (X = Ci-, Br-, or N O r ), and [Cu(L4)] (C104) 2 have been synthesized. The cobalt complexes represent the rarest examples of cobalt(II) macrocyclic complexes and exhibit spin cross-over with change in axial ligands. The lanthanide(III) complexes [Ln(L4)(HzO)z(NO3) ] (Ln = Pr 3 +, Nd 3 +, Sm 3 +, Eu 3 +, Gd 3 +, Tb 3 +, Dy 3 +, Ho 3 +, Er 3 +, and Tm 3 + ) and the uranyl(VI) complex [UO2(L4)] (NO3)2 have been synthesized either by the reaction of L 4 with the metal nitrate or by the template method. The ability of L 4 to coordinate with lanthanide(III) cations of varying sizes is due to its ability to fold according to the electronic requirements of the central metal ion and to the steric demands of the coordinated exocyclic ligands. The lanthanide(III) and uranyl(VI) complexes exhibit exceptional inertness towards the release of metal ions in solution. |
| Starting Page | 302 |
| Ending Page | 302 |
| Page Count | 1 |
| File Format | PDF HTM / HTML |
| DOI | 10.1007/BF02870069 |
| Volume Number | 108 |
| Alternate Webpage(s) | https://www.ias.ac.in/article/fulltext/jcsc/108/03/0302-0302 |
| Alternate Webpage(s) | https://doi.org/10.1007/BF02870069 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
