Distorted tetrahedral nickel-nitrosyl complexes: spectroscopic characterization and electronic structure

Abstract

The linear nickel-nitrosyl complex [Ni(NO)(L3)] supported by a highly hindered tridentate nitrogen-based ligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate (denoted as L3), was prepared by the reaction of the potassium salt of the ligand with the nickel-nitrosyl precursor [Ni(NO)(Br)(PPh 3 ) 2 ]. The obtained nitrosyl complexes as well as the corresponding chlorido complexes [Ni(NO)(Cl)(PPh 3 ) 2 ] and [Ni(Cl)(L3)] were characterized by X-ray crystallography and different spectroscopic methods including IR/far-IR, UV-Vis, NMR, and multi-edge X-ray absorption spectroscopy at the Ni K-, Ni L-, Cl K-, and P K-edges. For comparative electronic structure analysis we also performed DFT calculations to further elucidate the electronic structure of [Ni(NO)(L3)]. These results provide the nickel oxidation state and the character of the Ni-NO bond. The complex [Ni(NO)(L3)] is best described as [Ni (II) (NO (-) )(L3)], and the spectroscopic results indicate that the phosphane complexes have a similar [Ni (II) (NO (-) )(X)(PPh 3 ) 2 ] ground state.

Solution and Solid‐State Ligand K‐Edge XAS Studies of PdCl2 Diphosphine Complexes with Phenyl and Cyclohexyl Substituents

“…During the same year, Daly and Keith reported P K‐edge XAS studies of Ni(PPh 3 ) 2 Cl 2 and Pd(PPh 3 ) 2 Cl 2 to evaluate changes in M–P covalency as a function coordination geometry and trans influence . Szilagyi reported similar P K‐edge XAS studies in 2016 on Ni(PPh 3 ) 2 X 2 and Ni(NO)(PPh 3 ) 2 X, where X = halide, to evaluate the influence of nitrosyl binding on Ni II electronic structure …”

Simultaneous nitrosylation and N-nitrosation of a Ni-thiolate model complex of Ni-containing SOD

“…The ∼30 cm –1 downshift from 2 is likely due to a slight overestimation of Ni–NO bond covalency arising from Ni-dπ backbonding. Previous calculations on three-71 and four-coordinate43,72 {NiNO} 10 complexes support a Ni II – 3 NO – ( S tot = 0, antiferromagnetically coupled) oxidation state assignment. This is comparable to high-spin nonheme {FeNO} 7 systems that are classified as Fe III – 3 NO – ( S tot = 3/2) 6,66,73.…”

“…Complex 2 is analogous to the limited number of four-coordinate/S-bound Ni-nitrosyls,30–34 fewer of which contain Ni–S thiolate bonds31,33 which display Ni–N(O) (1.663–1.683 Å), N–O (1.131–1.173 Å), and Ni–N–O (156.6–173.9°) distances/angles in similar ranges. Even neutral/cationic P-35–40 and N-bound34,41–43 L 3 Ni–NO/L 2 XNi–NO complexes exhibit similar metric parameters. The coordinated nitrosamine is bent (N–N–O: 115.4°), i.e.…”

“…This property has been established in the {FeNO} 7 case, but not yet for {NiNO} 10 . Indeed, examination of the frontier MOs of 2* show that, much like other {NiNO} 10 systems with Tp ligands43,72 (Tp = tris(pyrazolyl)borate), the LUMO is a π* MO primarily comprised of antibonding interactions between Ni-dπ and NO-π* orbitals (Fig. S25†).…”

Structures and Properties of Dinitrosyl Iron and Cobalt Complexes Ligated by Bis(3,5-diisopropyl-1-pyrazolyl)methane

“…In our previous works, a series of first row transition metal complexes with NO, [M(NO)(L3)] (M = Fe, Co, Ni, and Cu), were prepared, structurally characterized and ligated by the same hydrotris(pyrazolyl)borate coligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate (denoted as L3 − , Scheme 1 left) [32][33][34][35]. Our synthetic strategy is to use exactly the same hindered supporting ligand to make four coordinate mono-nitrosyl transition metal complexes to directly compare their electronic properties and reactivities.…”