Synthesis, crystallographic and electrochemical study of ethynyl[2.2]paracyclophane-derived cobalt metallatetrahedranes

A series of alkynyl cobalt complexes [Co2(μ-η2-HCC–PCP)(CO)6−nLn] [n = 0 (2); n = 2, L2 = dppa (3), dppm (4), dcpm (6), 2 P(OPh)3 (7)] and [Co2(CO)4L2]2(μ-η2:μ-η2-HCC–PCP–CCH)] (L2 = dppm (8), dcpm (9); (PCP = [2.2]paracyclophane) has been prepared and characterized. The molecular structures of 3 and 4, as well as that of [Co2(CO)4(μ-CO)2(μ2-dcpm)] (5), have been determined by X-ray diffraction. Electrochemical studies (Cyclic Voltammetry, Rotating Disk Electrode) and luminescence spectroscopy have been used to evaluate the extent of the electronic communication through the PCP motif using the “Co2C2” centres as a probe. No electronic coupling between the Co2(CO)n centres via the bridging PCP-ligand was evidenced neither by electrochemistry nor by luminescence measurements in diyne complexes. A series of alkynyl cobalt complexes [Co2(μ-η2-HCC–PCP)(CO)6−nLn] [n = 0 (2); n = 2, L = dppa (3), dppm (4), dcpm (6), P(OPh)3 (7)] and [Co2(CO)4(L)]2(μ-η2: μ-η2-HCC–PCP–CCH)] (L = dppm (8), dcpm (9)) (PCP = [2.2]paracyclophane) has been prepared and characterized. The new complexes were studied by single crystal X-ray diffraction analysis, electrochemistry and fluorescence spectroscopy. [Display omitted] ► A series of alkynyl cobalt complexes has been prepared and characterized. ► The molecular structures of different compounds have been determined by X-ray diffraction. ► Electrochemical studies and luminescence spectroscopy have been used. ► No electronic coupling between the Co2(CO)n centres via the bridging PCP-ligand was evidenced.