Third-Generation Scorpionates [RBpz3]- - How Influential Is the Nondonor Substituent R?

Five pairs of perfluorophenyl- and phenyl-substituted tris(pyrazol-1-yl)borate complexes have been prepared and thoroughly investigated, namely, [(C(6)R(5)Bpz(3))(2)Fe], [(C(6)R(5)Bpz(3))(2)Cu], [(C(6)R(5)Bpz(3))Mn(CO)(3)], K[(C(6)R(5)Bpz(3))Mo(CO)(3)], and [(C(6)R(5)Bpz(3))Mo(CO)(2)(2-methallyl)] (R = F, H; pz = pyrazol-1-yl). X-ray crystal structure analyses and IR spectroscopical measurements reveal only a minor influence of the spectator substituents on the corresponding parameters. In contrast, significant differences between the redox potentials of the fluorinated and non-fluorinated species are evident in their cyclic voltammograms. Large differences have been found between the crystal packings of the complexes with perfluorinated and non-fluorinated phenyl rings.