Synthesis, reactions and X-ray crystal structures of metallacrown ethers with unsymmetrical bis(phosphinite) and bis(phosphite) ligands derived from 2-hydroxy-2′-(1,4-bisoxo-6-hexanol)-1,1′-biphenyl

Academic Article

Abstract

  • Chlorodiphenylphosphine and 2,2′-biphenylylenephosphorochloridite react with 2-hydroxy-2′-(1,4-bisoxo-6-hexanol)-1,1′-biphenyl to yield the new α,ω-bis(phosphorus-donor)-polyether ligands, 2-Ph PO(CH CH O) -C H -2′-OPPh (1) and 2-(2,2′-O C H )P(CH CH O) -C H -2′-P(2,2′-O C H ) (2). These ligands react with Mo(CO) (nbd) to form the monomeric metaflacrown ethers, cis-Mo(CO) {2-Ph PO(CH CH O) -C H -2′-OPPh } (cis-3) and cis-Mo(CO) {2-(2,2′-O C H )P(CH -CH O) -C H -2′-P(2,2′-O C H )} (cis-4), in good yields. The X-ray crystal structures of cis-3 and cis-4 are significantly different, especially in the conformation of the metal center and the adjacent ethylene group. The very different C-NMR coordination chemical shifts of this ethylene group in cis-3 and cis-4 suggest that the solution conformations of these metallacrown ethers are also quite different. Both metallacrown ethers undergo cis-trans isomerization in the presence of HgCl . Although the cis-trans equilibrium constants for the isomerization reactions are nearly identical, the isomerization of cis-3 is more rapid. Phenyl lithium reacts with cis-3 to form the corresponding benzoyl complexes but does not react with either trans-3 or cis-4. Both the slower rate of cis-trans isomerization of cis-4 and its lack of reaction with PhLi are consistent with weaker interactions between the hard metal cations and the carbonyl oxygens in both trans-3 and cis-4. © 1999 Elsevier Science S.A. All rights reserved. 2 2 2 2 12 8 2 2 12 8 2 2 2 12 8 2 12 8 4 4 2 2 2 2 12 8 2 4 2 12 8 2 2 2 12 8 2 12 8 2 13
  • Published In

    Digital Object Identifier (doi)

    Author List

  • Hariharasarma M; Lake CH; Watkins CL; Gray GM
  • Start Page

  • 328
  • End Page

  • 338
  • Volume

  • 580
  • Issue

  • 2