Synthesis, NMR characterization, and cation binding of metallacrown ethers with asymmetric Bis(phosphinite) and bis(phosphite) ligands derived from 2-hy droxy-2′-(1,4,7-trisoxo-9-nonanol)-1,1′-biphenyl

Academic Article

Abstract

  • Chlorodiphenylphosphine and 2,2′-biphenylylenephosphorochloridite react with 2-hydroxy2′-(1,4,7-trisoxo-9-nonanol)-1,1′-biphenyl to yield the new α,ω-bis(phosphorus-donor)polyether ligands Ph2PO(CH2CH2O)3-2-C12H 8-2′-OPPh2 and (2,2/-O2C12H8)P(CH2CH2O) 3-2-C12H8-2′P(2,2′-O2C 12H8). These ligands react with Mo(CO)4(nbd) to form the monomeric cis-metallacrown ethers cis-Mo(CO)4{Ph2PO(CH2CH2O)3 -2-C12H8-2′-OPPh2} and cis-Mo(CO)4{(2,2′-O2C12H8)P(CH 2CH2O)3-2-C12H8-2′- P(2,2′-O2C12H8)}. The X-ray crystal structure of cis-Mo(CO)4{(2,2′-O2C12H8)P(CH 2CH2O)3-2-C12H8-2′- P(2,2′-O2C12H8)} indicates that in the solid state three of the four metallacrown ether ring oxygens point away from the cavity in the cis-metallacrown ether ring. Both metallacrown ethers undergo cis-trans isomerization in the presence of catalytic amounts of HgCl2 but yield quite different products, cis-Mo(CO)4{Ph2PO(CH2CH2O)3 -2-C12H8-2′-OPPh2}·HgCl 2 and trans-Mo(CO)4{(2,2′-O2C12H8)P( CH2CH2O)3-2-C12H8-2 ′-P(2,2′-O2C12H8)}·HgCl 2, when reacted with a stoichiometric amount of HgCl2. NMR titrations of the cis-metallacrown ethers with lithium salts demonstrate that the cis-metallacrown ethers form 2:1 complexes with Li+. The unexpected 2:1 ratio has been confirmed by the isolation of [cis-Mo(CO)4{Ph2PO(CH2CH2O)3 -2-C12H8-2′-OPPh2]2LiBPh 4. In dichloromethane-d2 solution, this complex very slowly isomerizes to form a mixture of [trans-Mo(CO)4{Ph2PO(CH2CH2O)3 -2-C12H8-2′-OPPh2]LiBPh4 and the free cis-metallacrown ether, indicating that the frvzns-metallacrown ether more strongly binds Li+ than does the cis-metallacrown ether. Neither 2:1 stoichiometries for Li+ complexes of cis-metallacrown ethers nor complex formation by froms-metallacrown ethers have previously been reported.
  • Authors

    Published In

  • Organometallics  Journal
  • Digital Object Identifier (doi)

    Author List

  • Butler JM; Jablonsky MJ; Gray GM
  • Start Page

  • 1081
  • End Page

  • 1088
  • Volume

  • 22
  • Issue

  • 5