71089-11-7Relevant articles and documents
Barium complexes with crown-ether-functionalised amidinate and iminoanilide ligands for the hydrophosphination of vinylarenes
Le Coz, Erwann,Roueindeji, Hanieh,Roisnel, Thierry,Dorcet, Vincent,Carpentier, Jean-Francois,Sarazin, Yann
, p. 9173 - 9180 (2019/07/04)
The detailed multistep syntheses of two nitrogen-based sterically congested iminoanilidine and amidine proligands bearing a tethered 15-member aza-ether-crown macrocycle, namely {I^Acrown}H and {Amcrown}H, are reported. These proligands react with [Ba{N(SiMe2H)2}2·(thf)n] to generate the heteroleptic barium complexes [{I^Acrown}BaN(SiMe2H)2] (5) and [{Amcrown}BaN(SiMe2H)2] (6) in high yields. These complexes exhibit high coordination numbers (resp. eight and seven) and are in addition stabilised by mild Ba?H-Si interactions. Unusually for oxophilic elements such as barium, the amidinate ligand in 6 is only η1-coordinated. Complexes 5 and 6 mediate the intermolecular hydrophosphination of styrene with primary (PhPH2) and secondary (HPPh2) phosphines. Their catalytic performance compares favourably with those of other barium precatalysts for these reactions. During the course of the hydrophosphination of styrene with HPPh2 catalysed by 5, the phosphide complex [{I^Acrown}BaPPh2] (7) could be intercepted and crystallographically characterised.
Synthesis of new N-pivot lariat crown ethers containing a propylene linkage in the side arm
Katritzky, Alan R.,Denisko, Olga V.,Belyakov, Sergei A.,Schall, Otto F.,Gokel, George W.
, p. 7578 - 7584 (2007/10/03)
A series of new 15- and 18-membered N-pivot lariat aza-crown ethers having a propylene linkage in the side arm was prepared starting from functionalized diethanolamines and functionalized lariat aza-crown ethers containing the easily modified benzotriazole moiety. Addition reactions of such derivatives to electron-rich vinyl ethers or vinylamides followed by displacement of the benzotriazolyl group in the addition products by hydrogen (by reduction with LiAlH4) gives a variety of N-(3-oxo-3-substituted)- and N-(3-aza-3-substituted)propylene side-armed derivatives of aza-crown ethers. Stability constants for the complexes of several synthesized lariats with metal cations are discussed.
Direct ESR Evidence for Sodium Selective, Intramolecular Ion Pairing in Redox-Switched Nitrogen-Pivot Lariat Ethers
Delgado, Milagros,Echegoyen, Luis,Gatto, Vincent J.,Gustowski, Deborah A.,Gokel, George W.
, p. 4135 - 4138 (2007/10/02)
N-(2-Nitrobenzyl)aza-15-crown-5, 1, and the sidearm hexadeuterio analogue 2 have been reduced electrochemically to their corresponding radical anion forms and analyzed by ESR.Addition of Li(1+), Na(1+), or K(1+) to the solutions leads to changes in the ESR spectra but the changes are most marked when Na(1+) is present.Essentially no change is observed in the ESR spectrum of 2-nitrotoluene, confirming that both macroring and sidearm must be involved for the intramolecular ion pair to be stable.The radical anion sidearm compexes must be relatively rigid species since the strongest sidearm interaction is observed with Na(1+) cation which is closest in size to the cavity formed by the cooperating macroring and sidearm.
