Nucleophilic substitution of an iron(ii) dichloroclathrochelate with diphenylphosphine sulfide under PTC afforded a monophosphorylated cage complex. This precursor undergoes further nucleophilic substitution with mono- and diamines giving P,N-substituted mono- and bis-clathrochelates; those with thiophosphoryl and pyridyl groups were used as N,S-donor macrobicyclic ligands toward the palladium(ii) ion. In the resulting Pd,Fe-binuclear 1 : 1 complexes, the clathrochelate moieties retain the geometry, characteristic of low-spin iron(ii) complexes, with a minor distortion caused by intramolecular interactions. The Pd(2+) ion has a twisted square-planar N2SCl-environment. The complexes thus obtained proved to be efficient catalysts of the Suzuki cross-coupling reaction.
The 1,3-cycloaddition of ω-phosphoryl azides to activated internal alkynes such as dimethyl acetylenedicarboxylate and tetramethyl acetylenediphosphonate as well sodium azide to tetramethyl acetylenediphosphonate readily proceeds in water without any co-solvent or additive to afford the corresponding phosphorylated 1,2,3-triazoles in excellent yields. The ester group in carbalkoxy function of these compounds can be easily converted to carbamido group via the reaction with amines in MeOH thereby expanding the range of potentially biologically active heterocyclic aminophosphonates of such type.
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.
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