Chemical Transformations of (2,3,9,10‐Tetramethyl‐1,4,5,7,8,11,12,14‐Octa‐Azacyclotetradeca‐1,3,8,10‐Tetraenato)Cobalt(II)Perchlorate

Abstract

AbstractThe monomeric octa‐aza bis‐α‐diimine macrocyclic complex [CoII(C10H20N8)(H2O)](ClO4)2 I, undergoes various reactions on the macrocyclic ligand. Reaction of complex I with triethylamine in double molar proportions, followed by slow aerial oxidation, produces a molecular dimeric complex [CoII(C10H14N8)]2, III, and a novel Co(I) complex [CoI(C10H19N8)], IV. Complex III is a staggered cofacial dimer with a cobalt‐cobalt bond length 2.86(1) Å. The macrocyclic ligand of the complex contains an a‐diimine function in each five‐membered chelate ring, and a three‐atom N‐C‐N− delocalized system in each six‐membered chelate ring. Complex IV has the 5‐5‐6‐6 chelate arrangement because one α‐diimine moiety is rearranged to a syn‐anti configuration. In the structure, the two fused six‐membered chelate rings are fully conjugated and the two fused five‐membered rings are saturated. However, when complex I reacts with excess triethylamine under the similar conditions, a dimeric complex of another type, [CoII(C10Hl6N8)]2, II, was generated, in which one N‐N bond of the macrocyclic ligand is broken. Complex IV can be isolated also from the reaction of complex I with excess hydrazine, followed by slow aerial oxidation. When hydrazine in double molar proportions was used, complex [CoI(C10H17N8)(NHNH)] V, which contains a coordinated diazene ligand, was obtained. Only one six‐membered chelate ring of complex V is deprotonated and oxidized to form a three‐atom N‐C‐N− delocalized system. The structures of octa‐aza complexes I‐V are determined by X‐ray crystallography: I, orthorhombic, C mca, a = 11.646(4), b = 17.049(3), c = 10.706(3) Å, Z = 4, R = 0.045, Rw = 0.047, based on 1024 reflections with I > 2σ(I); II, monoclinic, P 21/c, a = 9.814(3), b = 22.583(6). c = 14.632(9) Å, β = 98.90(5)°, Z = 4, R = 0.085, Rw = 0.101, based on 2033 reflections with I > 2σ(I); III, tetragonal, P 4/nmm, a = 15.614(3), c = 6.498(2) Å, Z = 4, R = 0.081, Rw = 0.115, based on 340 reflections with I > 2σ(I); IV, orthorhombic, P bca, a = 8.484(1), b = 16.662(3), c = 18.760(2) Å, Z = 8, R = 0.029, Rw = 0.024, based on 1441 reflections with I > 2σ(I); V, monoclinic, P 21/m, a = 7.892(3), b = 11.713(6), c = 9.326(4) Å, β = 108.03(3), Z = 2, R = 0.047, Rw = 0.056, based on 948 reflections with I > 2σ(I).