Tunable Hemilabile Ligands for Adaptive Transition Metal Complexes

Abstract

A new family of monoanionic hemilabile ligands L1H-L3H with a PNN donor set has been developed, based on Pd-catalyzed C-N bond formation and straightforward phosphorylation. For these structurally related compounds with a hybrid set of donor atoms, the coordination chemistry with both Rh and Ir has been studied. The anticipated hemilabile character of the dimethylamino group was assessed by NMR and IR competition experiments, using isopropyl isocyanide as exogenous substrate. Supporting DFT calculations were used to quantify the electronic differences between the various members of the ligand family. In effect, we have constructed a modular ligand class that exhibits tunable hemilability.

Synthesis and Structures of Fluorinated (β‐Diketiminato)rhodium Complexes: Si–H Activation of Silanes at a Carbonyl Complex

“…[24d,24e] The presence of three absorption bands in the IR spectra of diisonitrile complexes has been documented in the literature. [24] The 13 C{ 1 H} NMR spectrum exhibits an unusually high-field-shifted [22] doublet resonance for the rhodium-bound carbon atoms at δ = 147.8 ppm with a rhodium-carbon coupling constant of 1 J Rh,C = 65.1 Hz. The structure of 4 in the solid state was determined by X-ray crystallography ( Figure 3); selected bond lengths and angles are summarized in Table 4.…”

“…The formal oxidation state of metal centers in transitionmetal complexes that contain π-accepting ligands such as carbonyl [7,12a,20,21] or isocyanido ligands [22][23][24] can be esti-mated by characteristic absorption bands of these π-acceptor ligands in the IR or Raman spectra. The use of such ligands might therefore provide a helpful tool to obtain information on the electronic properties of the metal center.…”

“…The solid-state IR spectrum of 4 shows three absorption bands at ν = 2137, 2094, and 2064 cm -1 for two CNtBu ligands at a rhodium(I) complex. [22][23][24] Spectra measured in toluene and THF also reveal three bands at ν = 2137, 2095, and 2061 cm -1 (toluene) and at ν = 2139, 2096, and 2061 cm -1 (THF). However, DFT calculations to model the IR spectrum of 4 in the gas phase show only two absorption bands at ν = 2189 and 2133 cm -1 (B3LYP/cc-pvdz).…”

“…These values are comparable to the data in other isocyanide complexes. [22][23][24] The rhodium isocyanide units exhibit angles of Rh1-C18-N3 177.5(2)°and Rh1-C23-N4 176.6(2)°. (4) tion bands at ν = 2140, 2103, and 2068 cm -1 for two CNtBu ligands in the IR spectrum (ATR).…”

“…(4) tion bands at ν = 2140, 2103, and 2068 cm -1 for two CNtBu ligands in the IR spectrum (ATR). [22][23][24] The 13 C{ 1 H}-NMR spectrum features a doublet resonance signal at δ = 150.5 ppm with a rhodium-carbon coupling constant of 1 J Rh,C = 63.0 Hz. The structure of 5 in the solid state was also determined by X-ray crystallography ( Figure 4); selected bond lengths and angles are summarized in Table 5.…”