This review is a comprehensive account of reactions with the participation of nickel complexes that result in the formation of carbon–phosphorus (C‒P) bonds. The catalytic and non-catalytic reactions with the participation of nickel complexes as the catalysts and the reagents are described. The various classes of starting compounds and the products formed are discussed individually. The several putative mechanisms of the nickel catalysed reactions are also included, thereby providing insights into both the synthetic and the mechanistic aspects of this phosphorus chemistry.

Pincer complexes play an important role in organometallic chemistry; in particular, their use as homogeneous catalysts for organic transformations has increased dramatically in recent years. The high catalytic activity of such bis-cyclometallic complexes is associated with the easy tunability of their properties. Moreover, the phosphorus-based unsymmetrical pincers showed higher catalytic activity than the corresponding symmetrical analogues in several catalytic reactions. However, in modern literature, an increasing interest in the development of catalysts based on non-precious metals is observed. For example, nickel, which is an affordable and sustainable analogue of platinum and palladium, known for its low toxicity, has attracted increasing attention in the catalytic chemistry of transition metals in recent years. Thus, this mini-review is devoted to the recent advances in the chemistry of unsymmetrical phosphorus-based pincer nickel complexes, including the ligand design, the synthesis of nickel complexes and their catalytic applications.

Metal-organic frameworks [M₂(2-I-bdc)₂bpe] (M = Zn(II) (1), Co(II) (2), 2-I-bdc = 2-iodoterephtalic acid, and bpe = 1,2-bis(4-pyridyl)ethane) were prepared and characterized by X-ray diffractometry. Both compounds retain their 3D structure after the removal of guest DMF molecules. Selectivity of sorption of different organic substrates from the gas phase was investigated for both complexes.

By methods of cyclic voltammetry and preparative electrolysis, the electrochemical properties of sterically hindered imidazolium salt 3-(6-(1H-pyrazol-1-yl)pyridin-2-yl)-1-(2,6-diisopropylphenyl)-1H-imidazol-3-ium bromide containing the pyrazolyl-pyridyl moiety are studied and the N-heterocyclic carbene complexes of nickel(II) are electrochemically synthesized by the cathodic reduction of this salt in the presence of nickel(II) ions. The monitoring of this preparative electrosynthesis by mass spectrometric measurements demonstrates that these organonickel complexes can contain either one (when a diaphragm cell is used) or two (when the diaphragmless cell contains a soluble nickel anode) N-heterocyclic carbene ligands.

The interaction between (PNP)PdH (1); PNP = bis(2-diisopropylphosphino-4-methylphenyl)amide and different acids (CF₃SO₃H, HBF₄∙Et₂O, fluorinated alcohols and formic acid) was studied in benzene or toluene as well as in neat alcohols by IR and NMR spectroscopies. The structures of hydrogen-bonded complexes were also optimized at the DFT/ωB97-XD/def2-TZVP level. The nitrogen atom of the amidophosphine pincer ligand readily accepts proton not only from strong Brønsted acids but from relatively weak fluorinated alcohols_. That suggests that binding to palladium(II) increases the diarylamine basicity, making it a strong base. Nevertheless, H⁺ can be taken from [(PN(H)P)PdH]⁺ (2) by pyridine or hexamethylphosphoramide (HMPA). These observations confirm the need for a shuttle base to form [(PN(H)P)PdH]⁺ (2) as the result of the heterolytic splitting of H₂ by [(PNP)Pd]⁺. At that, a stoichiometric amount of formic acid protonates a hydride ligand yielding an unstable η²-H₂ complex that rapidly converts into formate (PNP)Pd(OCHO), which loses CO₂ to restore (PNP)PdH, whereas the relatively high acid excess hampers this reaction through competitive protonation at nitrogen atom.