Size-Selective Reactions of cis-Mo(CO)4{Ph2P(CH2CH2O)nCH2CH2PPh2-P,P'} (n = 4, 5) Metallacrown Ethers with Mercury(II) Salts. Crystal Structure of cis-Mo(CO)4{μ-Ph2P(CH2CH2O)5CH2CH2PPh2-P,P',O,O',O″,O‴,O‴}•HgCl2, an Unusual Bimetallic Complex Containing a Molecular Cleft

Academic Article

Abstract

  • The reactions of mercury(II) salts with cis-Mo(CO)4{Ph2P(CH2CH2O)nCH2CH2PPh2-P,P'} (n = 5 (1), 4 (2)) metallacrown ethers are surprisingly complex, and the product depends upon the size of the metallacrown ether ring and the anion in the mercury(II) salt. The reaction of HgCl2 and 1 gives the bimetallic metallacrown ether complex, cis-Mo(CO)4{μ-Ph2P(CH2CH2O)5CH2CH2PPh2-P,P',O,O',O″,O‴,O″″}•HgCl2, 3, because the metallacrown ether ring is sufficiently large to accommodate the Hg2+. The X-ray crystal structure of 3 (triclinic space group P1̅, a = 10.387(2) Å, b = 13.0359(7) Å, c = 17.710(3) Å, α = 69.401(7)°, β = 81.32(1)°, γ = 87.15(1)°; V = 2218.8 Å3; Z = 2; R = 5.82; Rw= 7.19; GOF = 1.996 for 497 parameters and 7737 out of 9505 unique reflections) has been determined. The coordination environment of the Hg2+ is a hexagonal bipyramid with one missing equatorial ligand, axial chlorides, and equatorial ether oxygens. The open coordination site points toward the molybdenum, and the Mo—Hg distance is 6.8854(6) Å. In contrast, the reaction of HgCl2 and 2 results in the isomerization of 2 to trans-Mo(CO)4{Ph2P(CH2CH2O)4CH2CH2PPh2-P,P' }, 4. The Hg2+, which is too large to fit in the metallacrown ether ring in 2, catalyzes this isomerization, perhaps via coordination to the metallacrown ether and a lone pair on one of the carbonyl oxygens. Finally, the reaction of Hg(NO3)2•H2O and 1 results in the oxidation of the molybdenum carbonyl complex and the formation of a Hg2+ complex of Ph2P(CH2CH2O)5CH2CH2PPh2. This mercury complex is not formed when Hg(NO3)2•H2O is stirred with Ph2P(CH2CH2O)5CH2CH2PPh2 indicating that the metallacrown ether is required for the reaction to occur. © 1995, American Chemical Society. All rights reserved.
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    Published In

  • Organometallics  Journal
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    Author List

  • Gray GM; Duffey CH
  • Start Page

  • 245
  • End Page

  • 250
  • Volume

  • 14
  • Issue

  • 1