Complexes of ligands providing endogenous bridges. Part 7. The concurrent formation of 1 + 1 and 2 + 2 oxa-azamacrocycles; the X-ray crystal structure of an exocyclic dinuclear copper(II) complex

Abstract

A series of oxa-azamacrocycles derived from the non-template condensation of 1,3-diamino-2-propanol and acyclic dialdehydes followed by in situ reduction with tetrahydroborate has been prepared. Fast atom bombardment mass spectrometry (f.a.b.m.s.) showed the presence of 1 + 1 and 2 + 2 condensates and these were separated using medium pressure liquid chromatography. Metal complexes of the 1 + 1 macrocycles (HL) were prepared and characterised. Mononuclear complexes, M (HL)X₂, were recovered for M = Co^II, N^II, Zn^II, Cd^II, or Hg^II and X = Cl or Br and homo-dinuclear complexes, Cu₂LCl₂(OH)·nH₂O, for CuCl₂. The salts M(ClO₄)₂ and M(NO₃)₂(M = Co^II, Ni^II, Cu^II, Zn^II, or Cd^II) gave complexes [M(L)X] and f.a.b.m.s. provided evidence for oligomer formation. Mononuclear complexes were recovered from the reaction of one 2 + 2 macrocycle with M(ClO₄)₂(M = Co^II, Ni^II, or Zn^II) and CdCl₂, whereas a homodinuclear complex was obtained for Cu(ClO₄)₂. The crystal structure of [Cu₂(µ-C₁₉H₂₃N₂O₃)(µ-O₂CPh)(OH₂)Cl₂]·2PhCH₂OH reveals a dimeric structure in which the dinuclear units are linked by chloride bridges. The compound crystallises in monoclinic space group P2₁/c(C_2h⁵ no. 14) with unit-cell dimensions a= 13.460(15), b= 14.608(16), c= 17.096(8)Å, β= 96.227(9)°, and Z= 2; 3 678 independent reflections with I/σ(I) > 3.0 gave R= 0.0532.