A Multinuclear Nuclear Magnetic Resonance Study of Metal Complexes of the Ligands Ph2ECH2CMe2CH2EPh2 (E = P, As)

Academic Article

Abstract

  • The two chelating ligands 2,2-dimethyl-1,3-bis(diphenylphosphino)propane (2,2-dm-1,3-dppp) and 2,2-dimethyl-1,3-bis(diphenylarsino)propane (2,2-dm-1,3-dpap) have been synthesized and used to generate the new complexes Mo(CO) (L-L) W(CO) (L-L), and XMn(CO) (L-L) where X = Cl, Br, I, CH , and CH CO. A rapid chair-chair interconversion of the six-membered metal chelate ring system in the molybdenum and tungsten complexes results in the apparent equivalence of the phenyl groups ( C NMR), methyl groups ( H and C NMR), and methylene protons ( H NMR). The assignment of a facial configuration to each of the manganese complexes is based on infrared spectra in the 2000-cm region, a single P resonance for complexes of 2,2-dm-1,3-dppp, and the inequivalence of the 2-methyl groups ( H and C NMR), the phenyl groups ( C NMR), and the geminal methylene hydrogens ( H NMR). The H and C NMR spectra of the manganese complexes are interpreted on the basis of a single preferred chair conformation. Specific assignments for the H and C NMR resonance signals of the dissimilar 2-methyl groups are based upon the observation of four-bond planar W-coupling of the equatorial 2-methyl protons to phosphorus ( J ≃ 3 Hz) and Karplus-type three-bond coupling between phosphorus and the equatorial 2-methyl carbon ( J ≃ 10.5 Hz). Phosphorus coupling to the axial 2-methyl carbon ( J = 2.5 Hz) and protons is considerably weaker. © 1982, American Chemical Society. All rights reserved. 4 4 3 3 3 HP CP CP 13 1 13 1 −1 31 1 13 13 1 1 13 1 13 4 3 4
  • Authors

    Digital Object Identifier (doi)

    Author List

  • Kraihanzel CS; Ressner JM; Gray GM
  • Start Page

  • 879
  • End Page

  • 887
  • Volume

  • 21
  • Issue

  • 3