Water soluble diphosphine ligands based on 1,3,5-triaza-7-phosphaadamantane (PTA-PR2): Synthesis, coordination chemistry, and ruthenium catalyzed nitrile hydration

Abstract

Please cite this article as: J.M. Sears, W-C. Lee, B.J. Frost, Water Soluble Diphosphine ligands based on 1,3,5-triaza-7-phosphaadamantane (PTA-PR 2 ): synthesis, coordination chemistry, and ruthenium catalyzed nitrile hydration, Inorganica Chimica Acta (2015), doi: http://dx.ABSTRACT: Two chiral chelating 1,3,5-triaza-7-phosphaadamantane (PTA) derivatives were synthesized, in racemic form, by addition of ClP i Pr 2 or ClP(N i Pr) 2 (CH 2 ) 2 to lithiated PTA. PTA-P i Pr 2 (1) and PTA-P(N i Pr) 2 (CH 2 ) 2 (2) were isolated in good yield, 73 % and 56 % respectively, and fully characterized by multinuclear NMR spectroscopy, mass spectrometry, and X-ray crystallography. PTA-P i Pr 2 is highly air sensitive, but stable and somewhat soluble in degassed water. PTA-P(N i Pr) 2 (CH 2 ) 2 (2) is air-stable, but decomposes in water over the course of hours. Two tungsten tetracarbonyl complexes were prepared by addition of the PTA-PR 2 to [W(CO) 4 (pip) 2 ] and characterized by NMR and IR spectroscopies and X-ray crystallography in the case of [W(CO) 4 (PTA-P i Pr 2 )]. Based on IR spectroscopy PTA-P i Pr 2 (1) is more electron donating than PTA-P(N i Pr) 2 (CH 2 ) 2 (2) or the previously published PTAPPh 2 . Products isolated from the reaction of [(η 6 -toluene)RuCl 2 ] 2 with two equivalents of 1 were found to contain monodentate (κ 1 ), bidentate (κ 2 ), and possibly bridging coordination modes of PTA-P i Pr 2 . These ruthenium complexes were explored as catalysts for aqueous phase nitrile hydration. Of the ruthenium explored [(η 6 -toluene)RuCl 2 (κ 1 -PTA-P i Pr 2 )] (7) was the most active towards nitrile hydration. In the presence of air at 100 °C 7 converted various nitriles to the respective amides with 43-99% conversions in 7 h.

Pentafluorophenyl Platinum(II) Complexes of PTA and Its N-Allyl and N-Benzyl Derivatives: Synthesis, Characterization and Biological Activity

“…The water-solubility of 1,3,5-triaza-7-phosphaadamantane (PTA), its diverse mode of coordination, ease of functionalization and modification have made this compound a ligand of choice in coordination chemistry [1,2,3], catalysis [4,5,6,7,8,9,10,11,12] and bioinorganic chemistry [13,14]. N-Functionalization is the simplest modification of PTA; it leaves the cage structure and the P-coordinating ability intact and affords a series of cationic species with tunable properties in terms of hydrophilicity and reactivity.…”

Synthesis of Hydrophilic Phosphorus Ligands and Their Application in Aqueous‐Phase Metal‐Catalyzed Reactions

“…Additionally, PTA‐based Ru‐catalysts derived from ligands 108 c , [81] 109 a , [82] and PTA [95] itself were reported to operate under comparable conditions. It is worth mentioning that [RuCl(toluene) 108c ]Cl was extremely active exhibiting TON and TOF of up to 97000 and 285 h −1 , respectively [81] .…”

“…Moreover, two ruthenium complexes of 109 a were soluble in water as well. However, its phosphinediamine derivative was found to decompose in water, presumably by hydrolysis of the P−N bonds [82] …”

Enzymatic Approach to the Synthesis of Enantiomerically Pure Hydroxy Derivatives of 1,3,5-Triaza-7-phosphaadamantane

“…Such a functionalization was presented in several papers, of which the most important was the treatment of the reactive synthon PTA-Li 2 with various electrophiles, e.g., with dichlorophenylphosphine, carbon dioxide, aldehydes, ketones, or imines (Scheme ). …”