An infinite zigzag chain and the first linear chain of four copper atoms;: Still no copper-copper bonding

We have prepared and characterized ionic compounds containing linear or zigzag chains of copper inns. For [Cu-3(DPhIP)(2)](CuCl2) (1), in addition to the well-known [ClCuCl](-) anion, there is a cation with a linear chain of three Cu atoms bridged by two DPhIP anionic ligands (DPhIP represents the anion of 2,6-diphenyliminopiperidine). Each cation has weak interactions with two adjacent CuCl2- anions, and each anion interacts with two neighboring [Cu-3(DPhIP)(2)](+) cations farming an infinite zigzag chain of CUT atoms. Also reported here is the linear tetracopper chain cation in [Cu-4(DPhIP)(4)][CuCl2](2) (2). The [Cu-4(DPhIP)(4)](2+) cation has approximate D-2d symmetry. There are three Cu ... Cu distances of 2.518(2), 2.479(2), and 2.525(2) Angstrom. The terminal Cu atoms are 2-coordinate Cu-I while the two inner Cu atoms are 4-coordinate Cu-II. In spite of the diamagnetic nature of this compound, molecular orbital calculations (by various DFT techniques) indicate that no direct Cu-Cu bonds are present; instead the bridging ligand effects a strong coupling of the spins.