Synthesis and Characterization of 6,6′-(2,4,6-Triisopropylphenyl)-2,2′-bipyridine (tripbipy) and Its Complexes of the Late First Row Transition Metals

The synthesis of tripbipy, a new substituted bipyridine ligand (6,6′-(2,4,6-triisopropylphenyl)-2,2′-bipyridine), and the syntheses, structures, and magnetic properties of the first coordination compounds based on this ligand are described. Tripbipy was synthesized by the Suzuki coupling of 2,4,6-triisopropylphenyl boronic acid and 6,6′-dibromo-2,2′-bipyridine. Reported here are the tripbipy complexes of five late first row transition metal chlorides (MCl2; M = Fe, Co, Ni, Cu, Zn). Four of the complexes MCl2tripbipy (M = Fe, Co, Ni, Zn) crystallize in the space group P21/c and are isomorphous with one solvent molecule of crystallization. The complex CuCl2tripbipy crystallizes in the space group P212121 with two solvent molecules of crystallization. All MCl2tripbipy complexes are four coordinate and contain distorted tetrahedral metal centers. CuCl2tripbipy shows a pseudo Jahn−Teller distortion, and X-band electron paramagnetic resonance (EPR) in a toluene glass gives approximate g⊥,∥ values of 2.2 and 2.1. Magnetic measurements (M = Fe, Co, Ni, Cu) are consistent with high spin dn configurations (n = 6−9, S = 2, 3/2, 1, 1/2) tetrahedral complexes and give χMT values at 300 K of 3.56, 2.10, 1.01, and 0.37 cm3 M−1 K, respectively.