Synthesis, structures, photophysical properties, and catalytic characteristics of 2,9-dimesityl-1,10-phenanthroline (dmesp) transition metal complexes

The syntheses of the 2,9-dimesityl-1,10-phenanthroline (dmesp) metal complexes, [Cu(dmesp)(MeCN)]PF₆ (1), [Cu(dmesp)₂]PF₆ (2), Fe(dmesp)Cl₂ (3), Co(dmesp)Cl₂ (4), Ni(dmesp)Cl₂ (5), Zn(dmesp)Cl₂ (6), Pd(dmesp)MeCl (7), Cu(dmesp)Cl (8), and Pd(dmesp)₂Cl₂ (9), in good to high yields are described. These complexes were characterized by ¹H and ¹³C NMR spectroscopy, HR–MS (ESI and/or APPI), and elemental analysis (CHN). The solid-state structures of complexes 1–8 were determined by single-crystal X-ray analysis and their photophysical properties were also characterized. To demonstrate the versatility of this new platform, complexes 3–5, 8, and 9 were employed in the catalytic oligomerization of ethylene using modified methyl aluminoxane (MMAO) as the cocatalyst, where Co(II) and Ni(II) complexes (4 and 5, respectively) were found to exhibit moderate selectivity for catalytic dimerization of ethylene to butenes over tri- or tetramerization. Complex 8 is an effective catalyst of both the commonly encountered “click” reaction and amine arylation chemistries. Complexes 6 and 9 were found to be excellent catalysts for Friedel-Crafts alkylation and Suzuki-Miyaura coupling, respectively.