Solvothermal Syntheses and Physical Properties of Noncentrosymmetric Olefin–Copper(I) Coordination Compounds

Solvothermal reactions of CuX (X = Cl, Br) and the organic olefin ligand 1,3,5-tris­(diallylaminomethyl)-2,4,6-trimethylbenzene (TTB) in the presence of acid offered two novel olefin–copper­(I) coordination compounds with unprecedented CuX cluster structures. The <i>C</i>₃ symmetry of TTB leads to the formation of a novel <i>C</i>₃-symmetric CuX cluster in oligomer compound <b>1</b> (H₃TTB­[Cu₄Cl₃]) and CuX framework in the two-dimensional compound <b>2</b> (H₃TTB­[Cu₈Br₁₁]). However, the flexibility and kink of H₃TTB induce olefin–copper­(I) coordination compounds to crystallize in noncentrosymmetric space groups <i>R</i>3<i>c</i> and <i>R</i>3 for compounds <b>1</b> and <b>2</b>, respectively. In addition to the bowl-like structure of the olefin ligand and <i>C</i>₃-symmetric CuX cluster found in compound <b>1</b>, such bowl-like moieties are connected by another kind of <i>C</i>₃-symmetric CuX cluster to form a novel two-dimensional framework in compound <b>2</b>. The electron cloud distributions and energy levels of the frontier orbitals in both compounds have been calculated by a DFT program. Nonlinear optical property measurement results show that both compounds are second-harmonic generation (SHG) active. Compounds <b>1</b> and <b>2</b> display no phase transition according to the measurement of the temperature dependence of dielectric properties in the temperature range 100–300 K. The close packing and large density from the high CuX/ligand ratio in compound <b>2</b> correspond to the higher dielectric constant