137678-86-5Relevant articles and documents
Divergent Solution and Solid-State Structures of Mono- And Dinuclear Nickel(II) Pyridone Complexes
Goralski, Sean T.,Manes, Taylor A.,Lumsden, Simone E. A.,Lynch, Vincent M.,Rose, Michael J.
, p. 1070 - 1079 (2020)
The chelating 2-pyridone ligand (E)-6-(1-((2-(methylthio)phenyl)imino)ethyl)pyridin-2(1H)-one (1) has been used to synthesize five nickel(II) complexes that have been characterized by single-crystal X-ray diffraction, UV/vis and IR spectroscopies, and benchtop magnetometry. Reaction of NiX2 (X = BF4, Cl) with 1 yielded the C2-symmetric halide-bridged Ni dimers [(μ-F)Ni2(κN,N,O-1-)2(κN,N-1)2](BF4) (2) and [(μ-Cl)Ni2(κN,N,O-1-)2(κN,N-1-)(κN,N-1)] (3), where 2 is formed via a rare example of fluoride abstraction from BF4 - by a transition metal. Remarkably, the reaction of Ni(OAc)2 with 1 followed by different methods of crystallization yielded three different products: the dimer [(μ-OH2)Ni2(κN,N,O-1-)(κN,N-1-)(κN,N-1)(OAc)2] (4), as well as the monomers [Ni(κN,N-1-)2(MeOH)2] (5) and [Ni(κN,N-1-)(κN,N-1)(OAc)(OH2)] (6). This observation is emblematic of the soft energy landscape of coordination motifs and nuclearity that pyridone ligands provide with late 3d transition metals. To better understand the solution versus solid-state speciation, solid-state UV/vis reflectance and solution-state UV/vis absorbance spectra were obtained. Surprisingly, the solution-state UV/vis spectra of 4 and 6 each provided nearly identical absorption spectra (λmax ≈ 360 nm), which matched neither of the solid-state reflectance spectra of 4 or 6 (λ ≈ 590, 790, 970 nm; 3A2g → 3T1g 3A2g →1E2g, and 3A2g → 3T2g, respectively). Rather, the solution spectra are consistent only with the spectroscopic features (MLCT) of a conventional square-planar Ni(II) species.