Triple ring contraction of a [2+2] macrocyclic ligand
Schiff base condensation of 2,6‐diformylpyridine and 1,3‐diaminopropan‐2‐ol in the presence of a BaII template ion yields a complex containing a [2+2] macrocycle, [Ba2(μ1,2‐ClO4)2(H2 L1)2], where H2 L1 is 3,7,15,19,25,26‐hexaazatricyclo[126.96.36.199,13]hexacosa‐1(25),2,7,9(26),10,12,14,19,21,23‐decaene‐5,17‐diol. On transmetallation with CuII cations, the macrocycle undergoes three successive ring contractions, yielding crystals of (acetato‐κO)[26,28‐dioxa‐3,7,15,19,25,27‐hexaazahexacyclo[188.8.131.52,5.19,13.117,10.03,8]octacosa‐1(25),9(27),10,12,14,21,23‐heptaene‐κ5 N]copper(II) perchlorate, [Cu(CH3COO)(C20H22N6O2)]ClO4 or [Cu(CH3COO)(L2)]ClO4, in which the macrocycle ring size has been reduced from 20 members in H2 L1 to 16 in L2.
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Document Type: Research Article
Affiliations: Chemistry Department, Loughborough University, Loughborough LE11 3TU, England
Publication date: August 15, 2013