Inorganic Chemistry, Vol.54, No.24, 11669-11679, 2015
Heterobimetallic Complexes That Bond Vanadium to Iron, Cobalt, and Nickel
Zero-valent iron, cobalt, and nickel were installed into the metalloligand V[N(o-(NCH2P(Pr-i)(2))C6H4)(3)] (1, VL), generating the hetero-bimetallic trio FeVL (2), CoVL (3), and NiVL (4), respectively. In addition, the one-electron-oxidized analogues [FeVL]X ([2(ox)]X, where X = BPh4 or PF6) and [CoVL]BPh4 ([3(ox)]BPh4) were prepared. The complexes were characterized by a host of physical methods, including cyclic voltammetry, X-ray crystallography, magnetic susceptibility, electronic absorption, NMR, electron paramagnetic resonance (EPR), and Mossbauer spectroscopies. The CoV and FeV heterobimetallic compounds have short M-V bond lengths that are consistent with M-M multiple bonding. As revealed by theoretical calculations, the M-V bond is triple in 2, 2(ox), and 3(ox), double in 3, and dative (Ni -> V) in 4. The (d-d)(10) species, 2 and 3(ox), are diamagnetic and exhibit large diamagnetic anisotropies of -4700 X 10(-36) m(3)/molecule. Complexes 2 and 3(ox) are also characterized by intense visible bands at 760 and 610 nm (epsilon > 1000 M-1 cm(-1)), respectively, which correspond to an intermetal (M -> V) charge-transfer transition. Magnetic susceptibility measurements and EPR characterization establish S = 1/2 ground states for (d-d)(9) 2(ox) and (d-d)(11) 3, while (d-d)(12) 4 is S = 1 based on Evans' method.