Reactions of coordinated ligands. Part 19: Template synthesis of a macrocyclic secondary tetraphosphine by oxidative demetallation of crown phosphineNi(II) complexes

The nickel(II) complex 3 containing a 14-membered macrocyclic triphosphine phosphinate ligand is obtained by regioselective oxidation of the crown pho sphine nickel(II) complex 2c with molecular oxygen. The X-ray structure of 3 . H2O (space group P2(1)/c) has been determined. Oxidation of the macrocy clic phosphinous acid nickel(II) complex 2a (P-4 donor set) with H2O2/HCl o r Br-2 and subsequent demetallation affords the macrocyclic phosphinic acid 5. Reaction of its methylester 6 with thionyl chloride and subsequent redu ction with LiAlH4 gives the novel macrocyclic PH functional tetradentate ph osphine 8 in high yields. (C) 1999 Elsevier Science Ltd. All rights reserve d.