Synthesis and Characterization of Some New 22‐Membered Chalcogenoaza Macrocycles and Their Co II and Ni II Complexes

The [2+2] cyclocondensation of bis( o ‐formylphenyl)chalcogenides ( 9 , 10 ) with trans ‐1,2‐diaminocyclohexane affords novel macrocyclic ligands 11 and 12 in very good yields. Crystals of 11 are triclinic, space group P $\bar {1}$ with a = 11.4037(11), b = 11.8184(12), c = 14.6835(14) Å, Z = 4 and those of 12 are triclinic, space group P $\bar {1}$ with a = 11.2692(9), b = 12.8612(11), c = 15.2439(12) Å and Z = 2. Reduction of 11 with sodium borohydride affords macrocycle 13 . The coordination chemistry of 11 has been studied with the “hard” metal ions Ni II and Co II . Reaction of NiCl 2 · 6H 2 O with one molar equivalent of 11 in refluxing methanol followed by addition of NH 4 PF 6 affords Ni II complex 14 . The assignment of an octahedral geometry to 14 follows from its paramagnetism ( μ eff = 2.50 μ B ) and UV/Vis spectrum and was further confirmed by single‐crystal X‐ray diffraction studies. The crystal structure of 14 consists of a distorted octahedral nickel center coordinated by two selenium and four nitrogen atoms. Complex 14 : hexagonal, space group P 6 1 , a = 17.0747(16), b = 17.0747(16), c = 29.958(4) Å, Z = 6. Co II complexes 15 and 16 of selenaaza macrocycles were prepared by the reaction of Co(ClO 4 ) 2 · 6H 2 O with 11 and 3 , respectively. Complex 16 : monoclinic, space group C 2 , a = 17.160(2), b = 10.9660(14), c = 9.4941(12) Å, Z = 2. The cyclic voltammograms of 15 and 16 in MeCN solution show well‐behaved quasi‐reversible couples.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)