Tellurium azamacrocycles: synthesis, characterization and coordination studies

Abstract

The metal-free condensation of bis(2-formylphenyl) telluride ( 1) with a series of diamines affords macrocyclic tellurium ligands 2– 7. Crystals of the protonated macrocycle 8 are monoclinic, space group P2/ n with a=10.890(5), b=7.414(4), c=24.334(13) Å, Z=2. The reaction of tellurium containing macrocyclic Schiff base 2 with Pd(C 6H 5CN) 2Cl 2 gives the expected 1:1 product [Pd(II) 2] Cl 2 ( 9). Complex 9 was treated with excess of NH 4PF 6 in methanol to give the analogous PF 6 − salt [Pd(II) 2] (PF 6) 2 ( 10). The crystals of 10 are monoclinic, space group P2 1/ n, a=8.2250(10), b=21.280 (4), c=21.150 (4), Z=4. However, the reaction of 2 with Pt(COD)Cl 2 proceeds via novel transmetallation to yield an organoplatinum complex ( 11). The crystals of 11 are also monoclinic, space group P2 1/ n, a=12.3253 (14), b=14.6557 (14), C=13.4054 (11), Z=4. The octahedral Ni(II) complex 12 was prepared by the reaction of NiCl 2 · 6H 2O with 2 and NH 4PF 6 under an inert atmosphere. For 12: triclinic, space group P 1 ̄ ; Z=2; a=10.800(8), b=13.468(9), c=13.918(11), α=89.67(6)°, β=101.53(7)°, γ=81.49(3)° and V=1961(3). Cyclic voltammetry of 12 in MeCN solution shows a well-behaved quasi-reversible (Δ E=100 mV) Ni(III) ↔ Ni(II) couple.