Igor D. Strelnik

New Functional Cyclic Aminomethylphosphine Ligands for the Construction of Catalysts for Electrochemical Hydrogen Transformations

Eight-membered cyclic functional bisphosphines, namely 1,5-di-aryl-3,7-di(2-pyridyl)-1,5-diaza-3,7-diphosphacyclooctanes (aryl=2-pyridyl, m-tolyl, p-tolyl, diphenylmethyl, benzyl, (R)-(+)-(α-methyl)benzyl), with 2-pyridyl substituents on the phosphorus atoms have been synthesized by condensation of 2-pyridylphosphine, formaldehyde, and the corresponding primary amine. The structures of some of these bisphosphines have been investigated by X-ray crystallography. The bisphosphines readily form neutral P,P-chelate complexes [(κ(2)-P,P-L)MCl2], cationic bis-P,P-chelate complexes [(κ(2)-P,P-L)2 M](2+), or a five-coordinate complex [(κ(2)-P,P-L)2 NiBr]Br. The electrochemical behavior of two of the nickel complexes, and their catalytic activities in electrochemical hydrogen evolution and hydrogen oxidation, including the fuel-cell test, have been studied.

Nickel complexes with cyclic ligands containing P and N atoms as coordination sites: novel biomimetic catalysts for hydrogen oxidation

Nickel complexes with new cyclic ligands containing phosphorus and nitrogen atoms as coordination sites are novel efficient catalysts for hydrogen oxidation. A systematic study of their electrochemical properties made it possible to classify the nickel systems in question into four groups according to the sequence of electron transfer processes in the reduction (MII-MI-M0) and to the nature of solvents and counterions. Regularities of catalytic transformations involving nickel complexes with P,N-cyclic ligands in the H2 oxidation reaction in the coordination sphere of the catalyst and a correlation between the structure of the complex and its redox properties were established. The most efficient catalysts contain phenyl and 2-pyridyl substituents at the phosphorus atom and benzyl or 2-pyridyl substituents at the nitrogen atom.

FIRST EXAMPLE OF 14-MEMBERED CYCLIC AMINOMETHYLPHOSPHINE

Abstract We report here a synthesis and molecular structure of novel 1,8-diisopropyl-3,6,10,13-tetraphenyl-1,8-diaza-3,6,10,13-tetraphosphacyclotetradecane.

“Host–guest” binding of a luminescent dinuclear Au(I) complex based on cyclic diphosphine with organic substrates as a reason for luminescence tuneability

This work introduces a luminescent dinuclear Au(I) complex with a cyclic PNNP ligand ((AuCl)2L) as a “host” molecule with two binding sites, “upper” and “lower”. The “upper” binding site is nucleophilic due to two preorganized Au–Cl moieties, while the “lower” one is electrophilic due to positive partial charges of hydrogen atoms of P–CH2–N moieties. The “host–guest” binding is a reason for both solvent- and substrate-induced tuning of the complex luminescence. Organic cations, namely N-methylpyridinium and trimethylammonium, are revealed as substrates able to bind via the “upper” site of the complex. Acetone, diphenylketone, DMSO, DMF and acetonitrile exemplify substrates able to bind with both the binding sites of the complex. The binding via “lower” sites leads to changes in mutual arrangement of pyridyl moieties and P–Au bonds of the complex, which results in a more pronounced effect on the excited state energy relative to the binding via the “upper” site. Substrate-induced tuning of the luminescence is affected by the nature of the solvent due to competitive “host–guest” binding of (AuCl)2L with solvent molecules.

Synthesis of 1-(pyridylalkyl)-1-aza-3,6-diphosphacycloheptanes

Reactions of 1,2-bis[(hydroxymethyl)(phenyl)phosphino]ethane with primary pyridylalkylamines gave earlier unknown 1-aza-3,6-diphosphacycloheptanes containing the pyridyl group in the exocyclic substituent. The reactions were found to be stereoselective, preferentially yielding the racemate with the RR/SS-configuration of the P atoms. A mixture of diastereomers of 3,6-diphenyl-1-[2-(2-pyridyl)ethyl]-1-aza-3,6-diphosphacycloheptane reacted with dichloro(cycloocta-1,5-diene)platinum(II) to give cis-P,P-chelate complexes from the meso-isomer and bridged oligomeric complexes from the racemate.

Nickel(II) Complexes of Novel P,N-Heterocycles Based on Pyridylphosphines

Abstract Novel 1,5-diaza-3,7-diphosphacyclooctanes were synthesized by Mannich-type condensation of pyridylphosphine, formaldehyde, and primary amines. Their interaction with Ni(II) salts containing different counterions was studied. GRAPHICAL ABSTRACT

Cyclic aminomethylphosphines as ligands. Rational design and unpredicted findings

Abstract: Rational design of title ligands and their transition metal complexes gave the high effective catalysts for hydrogen economy and perspective “stimuli-responsive” luminescent materials. Together with the above novel cyclic aminomehtylphospine ligands have showed a row of unpredicted properties like spontaneous formation of macrocyclic molecules, unique reversible slitting of macrocycles on to the smaller cycles, rapid interconversion of the isomers catalyzed by both acids and transitional metals, bridging behavior of usually chelating ligands and unexpected high influence of handling substituents on N-atoms on to the catalytic and luminescent properties of P-complexes.

New catalysts for PEM fuel cells

GRAPHICAL ABSTRACT ABSTRACT Fuel cell (FC) test results have been obtained for the first time with the bis-ligand nickel(ii) complex of 1,4-diaza-3,7-diphosphacyclootane heterogeneous catalyst. Using AFM technique the [Ni(PPh2Np-Tol2)2](BF4)2 self-assemblies morphology on pyrolytic graphite has been studied. By the method of rotating disk electrode the mechanism of FC cathode side reaction has been investigated

Synthesis of Bis(2-Pyridylphosphino)Alkanes in Superbasic Medium and Their Hydroxymethyl Derivatives

Abstract Novel P-H-diphosphinoalkanes with pyridyl substituents at the phosphorus atoms have been obtained in good or moderate yields by the interaction of primary 2-pyridyl-phosphine with dichloroalkanes in superbasic medium. The formation of novel 1-(2-pyridyl)-1-phosphacyclopentane together with bis(2-pyridylphosphino)butane was observed as the result of the interaction of 2-pyridylphosphine and 1,4-dichlorobutane under the same reaction conditions. The reaction of the bis(2-pyridylphosphino)alkanes thus obtained with formaldehyde leads to the formation of the corresponding hydroxymethyl derivatives. GRAPHICAL ABSTRACT

Nickel-organic complexes as catalyst in PEM fuel cells

GRAPHICAL ABSTRACT ABSTRACT Bis-ligand nickel(ii)complex of 1,4 -diaza-3,7-diphosphacyclootanes with phenyl and p-tolyl substituents of nitrogen and phosphorus atoms correspondingly has been found as an oxygen reduction reaction (ORR) catalyst for hydrogen/oxygen polymer electrolyte membrane (PEM) fuel cell.