Synthesis and structural characterization of the dichloride complex formed by carb­oxy-functionalized Cu(di­aza­cyclam)2+ cation and its heterometallic coordination polymer with CdCl2

The coordination polyhedra of the Cu^II ions in mol­ecular complex I and coordination polymer II represent tetra­gonally elongated trans-CuN₄Cl₂ and trans-CuN₄(H₂O)Cl octa­hedra, respectively, with the four N atoms of the macrocyclic ligand forming the equatorial plane and monodentate ligands occupying the axial positions. The coordination polyhedron of the Cd^II ion in II is a CdO₄Cl₂ distorted octa­hedron formed by two bidentately coordinated deprotonated carb­oxy­lic groups of different Cu^II macrocyclic cations and two chloride anions, one of which displays a bridging function.

The asymmetric unit of the complex [3,10-bis­(3-carb­oxy­prop­yl)-1,3,5,8,10,12-hexa­aza­cyclo­tetra­decane-κ⁴N¹,N⁵,N⁸,N¹²]di­chlorido­copper(II), [CuCl₂(C₁₆H₃₄N₆O₄)] or [Cu(H₂L)Cl₂] (I), consists of a centrosymmetric macrocyclic Cu^II dication and a chloride anion. The components of the heterometallic compound poly[[aqua­[μ₃-3,10-bis­(3-carb­oxy­prop­yl)-1,3,5,8,10,12-hexa­aza­cyclo­tetra­dec­ane-κ⁴N¹,N⁵,N⁸,N¹²:κ²O,O′:κ²O′′,O′′′]-μ-chlorido-­copper(II)cadmium(II] 1.25-hydrate], {[CuCd(C₁₆H₃₂N₆O₄)Cl₂(H₂O)]·1.25H₂O}_n or {[CuCd(L)(H₂O)Cl₂]·1.25H₂O}_n (II) are [Cu(L)(H₂O)] moieties coordinated to CdCl₂ units via the deprotonated carb­oxy­lic groups of the macrocycle, and four water mol­ecules of crystallization with partial occupancies. In each compound, the Cu^II ion coord­inates in the equatorial plane by the four secondary N atoms of the macrocyclic ligand, which adopts the most energetically stable trans-III conformation, and two mutually trans axial ligands in tetra­gonally elongated trans-CuN₄Cl₂ and trans-CuN₄(H₂O)Cl octa­hedral geometries in I and II, respectively. The coordination environment of the Cd^II ion in II is a CdO₄Cl₂ distorted octa­hedron formed by two bidentately coordinated deprotonated carb­oxy­lic groups of different macrocycles and two chloride anions, one of which displays a μ₂-bridging function between the Cu^II and Cd^II ions. The extended structures of both complexes are distinctly lamellar. In particular, due to hydrogen–bonding inter­actions with participation of carb­oxy­lic groups, chloride atoms and secondary amino groups of the macrocycle, the electro-neutral mol­ecules in crystal of I are arranged in chains running in the [101] direction; hydrogen bonding between the chains leads to layers parallel to the (101) plane. In crystal of II, polymeric chains running along the [101] direction are joined into layers parallel to the (101) plane via formation of Cu—Cl bonds and inter­chain hydrogen bonds. There are no hydrogen-bonding inter­actions between the layers and the three-dimensional structure of II is based on the weak C—H⋯O and C—H⋯Cl contacts.