Di- and trinuclear olato-bridged copper(II) compounds of 3,7-bis(3-olatopropyl)-1,3,5,7-tetraazabicyclo[3,3,1]nonane (protan 2−); the structures of [{Cu(μ-protan)} 2Cu](ClO 4) 2·H 2O and [{Cu(μ-protan)}Cu(OH) 2](ClO 4) 2·0.5(EtOH)

Abstract

A compound with a linear trinuclear copper(II) cation, [Cu 3(μ-protan) 2](ClO 4) 2·H 2O (protanH 2 = 3,7-bis(3-hydroxypropyl)-1,3,5,7-tetraazabicyclo[3,3,1]-nonane) is formed by reaction of copper(II) perchlorate, 3-aminopropanol, ammonia and methanal. The cation is approximately centrosymmetrical with Cu⋯Cu = 2.9870(5) and 2.9485(5) Å. The terminal copper(II) ions are coordinated by nitrogen atoms 3 and 7 of the tetraazabicycle (Cu–N mean = 2.021(5) Å) and the two oxygen atoms of the 3,7-bis(3-olatopropyl) substituents (Cu–O mean = 1.911(3) Å), which also act as bridging groups to the central copper(II) ion (Cu–O mean = 1.926(4) Å). The cation is both helically twisted (dihedral angle N3⋯N7⋯N3′⋯N7′ = 20(1)°) and bent (angle Cu⋯Cu⋯Cu = 171(1)°). The copper(II) ions have tetrahedrally twisted square planar primary coordination, with perchlorate ion oxygen atoms weakly coordinated axially to the two terminal copper(II) ions, on opposite sides of the “plane” of the molecule, while the central copper(II) ion is weakly coordinated axially by a water molecule, with all axial Cu–O distances ca. 2.9 Å. One N·CH 2·CH 2·CH 2·O chelate ring for each protan 2− ligand shows conformational disorder and the perchlorate ions show rotational disorder. Partial hydrolysis of the protan 2− compound gave a compound [{Cu(μ-protan)}Cu(OH) 2](ClO 4) 2·0.5(EtOH) which has a dinuclear cation, with one copper(II) ion in square-planar coordination by tetradentate protan 2− and the other in square-planar coordination by the two bridging oxygen atoms of the protan 2− ligand and by two hydroxide ions, with Cu⋯Cu = 3.045(1) Å. With differing mole ratios of the same reactants compounds of the dinuclear cation [{Cu(μ-pta)} 2] 2+ (ptaH = 3(3-hydroxypropyl)-1,3,5,7-tetraazabicyclo[3,3,1]nonane) are formed.