Synthesis and Coordination Chemistry of Cyano-Substituted Phosphines

Abstract

Synthetic approaches to both linear and cyclic cyano-substituted phosphines (P~CN-phosphines) found an industrial application as catalyst precursors, pesticides, herbicides, flame retardants, precursors of aminophosphines etc., are reported. The main synthetic routes include reduction of P=O containing precursors, alkylation of silylphosphines and metal phosphides by halogenoalkyl(aryl)carbonitriles, phosphorylation of the latter ones, decomposition of phosphonium salts and hydrophosphination of cyano-substituted olefins proceeding under non-catalytical conditions and with use of metal complex catalysis. Merits and demerits of each approach are discussed. Phosphines bearing cyano function as an additional coordination site show diverse coordination behavior depending on the phosphine structure and nature of the metal. Four main types of complexes are observed, namely those with P-monodentate coordination, with N-monodentate coordination and complexes where bidentate coordination mode of P and N atoms is realized either at the single metal atom or of bridged type between two different metal atoms. Thus coordination behavior of such P~CN-ligands relative to transition and non-transition metals, structure features of the complexes obtained and their application in catalytic processes are discussed.

Diastereoselective cycloalkylation of phosphoryl and thiophosphoryl acetonitriles by α,ψ‐dihalogenalkanes under phase transfer catalysis conditions

“…Under other conditions being equal, less sterically hindered gemdisubstituted butanes 4 and pentanes 5 are formed more easily and in higher yields in comparison with the corresponding cyclopropanes 3. Furthermore, the reaction is very sensitive to steric hindrances at the phosphorus atom and all other conditions being equal, the reaction rate decreased in the series (EtO) 2 …”

“…A diversity of structural types of known P,N-ligands including the sp-hybridized nitrogen atom of the cyano function as an additional coordination site is not too wide. Nevertheless, they show interesting and diverse coordination behavior depending on the phosphine structure and nature of the metal [2]. Data concerning their usage in homogeneous catalysis are essentially limited by application of tris(␤-cyanoethyl)phosphine in catalytic hydrophosphination [3], hydroformylation [4], alcohol carbonylation [5], etc.…”

Enantioselective Directed Nickel-Catalyzed Three-Component Reductive Arylalkylation of Alkenes via the Carbometalation/Radical Cross-Coupling Sequence

“…Notably, the addition of aryl nitrile as an additive is beneficial to improve enantioselectivity (entries 2, 4–6). Many precedent reports have demonstrated that electron-withdrawing benzonitriles as additives or ligands can promote Csp 3 –Csp 3 reductive elimination or stabilize the zerovalent nickel species in Ni catalysis. − Other nickel catalysts were explored but proved to be ineffective for arylalkylation (entries 7–9). Higher temperatures resulted in a lower er, while no product was observed when the temperature was reduced to 20 °C (entries 10 and 11).…”

Regiocontrolled Reductive Vinylation of Aliphatic 1,3-Dienes with Vinyl Triflates by Nickel Catalysis

“…Aliphatic dienes with diverse steric properties and simple butadiene and aromatic derivatives were all tolerated. The success of this effort depends on the use of phosphine–nitrile ligands, which have rarely been used in the area of transition-metal catalysis . It thus offers an approach to skipped dienes (1,4-dienes) with a scope that is complementary to the established methodologies. ,,,,− …”