Hydrothermal synthesis, crystal structure and third-order non-linear optical property of a discrete decanuclear iodocuprate(I) [Cu10H2I16] with [Ni(phen)3] as a template

The title compound Ni^II(phen)₃]₂Cu₁₀H₂I₁₆] 1 (phen=1,10-phenanthroline, C₁₂H₈N₂) was hydrothermally synthesized from a simple reaction of CuI-NiCl₂·6H₂O-phen·H₂O-H₂O. X-ray analysis revealed that it consists of NiN₆²⁺ core cation and decanuclear iodocuprate(I) anion together with two dissociative H⁺ ions. In anionic unit, the discrete decanuclear iodocuprate(I) is formed by crystallographically independent five monovalent copper atoms and eight iodine atoms via an inversion center. There exist two types of Cu(I) coordination sites; only one copper(I) atom is in a highly distorted triangular planar site, and the other four copper(I) atoms display the tetrahedral geometries. It deserves to be noted that four types of bridging modes of I⁻ ions in which two are ordinary μ₂- and μ₃-bonding modes can be found. But the other two are the rectangle planar geometry and the novel μ₄-bridge like an “umbrella”, and both of them are rather rare in the halocuprates(I). Compound 1 was crystallized in triclinic space group with a=11.6861(17), b=14.590(2), c=14.649(2) Å, α=76.370(2), β=70.830(2), γ=81.320(3)^o, R=0.075, and was characterized by elemental analysis, IR spectrum and UV-VIS spectrum. The third-order non-linear optical property of 1 was also investigated and the compound exhibits the reverse saturable absorption and self-defocusing performance.