Abstract

The crystal structure of the new double CuII complex salt, [Cu(L)(H2O)2][Cu(L)]Br4·2H2O (L = 3,14-diethyl-2,6,13,17-tetra-aza-tri-cyclo-[16.4.0.07,12]docosane, C22H44N4) has been determined using synchrotron radiation. The asymmetric unit contains one half of a [Cu(L)(H2O)2]2+ cation, one half of a [Cu(L)]2+ cation (both completed by crystallographic inversion symmetry), two bromide anions and one water solvent mol-ecule. The CuII atom in the first complex exists in a tetra-gonally distorted octa-hedral environment with the four N atoms of the macrocyclic ligand in equatorial and two aqua ligands in axial positions, whereas the CuII atom in the second complex exists in a square-planar environment defined by the four nitro-gen atoms of the macrocyclic ligand. The two macrocyclic rings adopt the most stable trans-III configuration with normal Cu-N bond lengths from 2.016 (3) to 2.055 (3) Å and an axial Cu-O bond length of 2.658 (4) Å. The crystal structure is stabilized by inter-molecular hydrogen bonds involving the macrocycle N-H or C-H groups and the O-H groups of water mol-ecules as donor groups, and the O atoms of water mol-ecules and bromide anions as acceptor groups, giving rise to a one-dimensional network extending parallel to [100].

Highlights

  • According to recent investigations, 1,4,8,11-tetraazacyclotetradecane derivatives and their transition-metal complexes show antiviral, antimicrobial and antibacterial activities (Ronconi & Sadler, 2007; Ross et al, 2012; Alves et al, 2017, 2019; De Clercq, 2019)

  • The design of new drugs with these moieties depends on the configuration, substituent and coordination behavior of the cyclam-based macrocycle (Valks et al, 2006)

  • We report on the synthesis and structural characterization of the new double CuII complex, namely, [Cu(L)(H2O)2][Cu(L)]Br4Á2H2O, (I), to determine the configuration of the macrocycles and the bonding properties of the water molecules and bromide anions in the crystal

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Summary

Chemical context

1,4,8,11-tetraazacyclotetradecane (cyclam) derivatives and their transition-metal complexes show antiviral, antimicrobial and antibacterial activities (Ronconi & Sadler, 2007; Ross et al, 2012; Alves et al, 2017, 2019; De Clercq, 2019). Novel cyclams and their CuII and FeIII complexes have been studied as anticancer agents (Pilon et al, 2019). The design of new drugs with these moieties depends on the configuration, substituent and coordination behavior of the cyclam-based macrocycle (Valks et al, 2006). To the best of our knowledge, the preparation and crystal structure for any double metal complex containing the macrocycle L have not been reported. We report on the synthesis and structural characterization of the new double CuII complex, namely, [Cu(L)(H2O)2][Cu(L)]Br4Á2H2O, (I), to determine the configuration of the macrocycles and the bonding properties of the water molecules and bromide anions in the crystal

Structural commentary
Supramolecular features
Database survey
Synthesis and crystallization
Refinement
Findings
C22 H22A H22B H22C
Full Text
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