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) A, Z = 2. The reaction of tellurium containing macrocyclic Schiff base 2 with Pd(C6H5CN)(2)Cl-2 gives the expected 1: 1 product [Pd(II) 2] Cl-2 (9). Complex 9 was treated with excess of NH4PF6 in methanol to give the analogous PF6- salt [Pd(II) 2] (PF6)(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 organoplatinurn 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(11) complex 12 was prepared by the reaction of NiCl2 . 6H(2)O with 2 and NH4PF6 under an inert atmosphere. For 12: triclinic, space group P (1) over bar; Z = 2; a = 10.800(8), b = 13.468(9), c = 13.918(11), alpha = 89.67(6)degrees, beta = 101.53(7)degrees, gamma = 81.49(3)degrees and V = 1961(3). Cyclic voltammetry of 12 in MeCN solution shows a well-behaved quasi-reversible (DeltaE = 100 mV) Ni(Ill) <----> Ni(11) couple. (C) 2004