Skip to main content
Spin delocalization in the Copper(I) Complexes of Bis(verdazyl) Diradicals
Journal of the American Chemical Society (1997)
  • David J R Brook, San Jose State University
  • Vincent Lynch, University of Texas at Austin
  • Brenda Conklin, University of Texas at Austin
  • Marye Anne Fox, University of Texas at Austin
1,1‘,5,5‘-tetramethyl-6,6‘-dioxobis(verdazyl) (BVD) reacts with copper(I) halides in acetonitrile and copper(II) halides in methanol to give copper(I) coordination polymers of composition [Cu2X2(BVD)]x. When X = Cl and X = Br, these polymers crystallize in orthorhombic unit cells with dimensions a = 6.684(1) Å, b = 12.524(3) Å, and c = 8.717(2) Å (X = Cl) and a = 12.680(2) Å, b = 6.744(1) Å, and c = 8.822(2) Å (X = Br). With X = I, powder diffraction indicates a monoclinic unit cell with dimensions a = 12.669 Å, b = 8.461 Å, c = 7.679 Å, and β = 91.88°, although poor crystal quality prevented a full structure determination. Magnetic susceptibility measurements taken on the three polymers indicate that the spins couple in one-dimensional chains with alternating exchange parameters:  J1 = −190 cm-1, J2 = −116 cm-1 (X = Cl); J1 = −200 cm-1, J2 = −110 cm-1 (X = Br); and J1 = −271 cm-1, J2 = −200 cm-1 (X = I). Variable temperature ESR measurements on the unstable monomeric complex resulting from reaction of BVD with (CH3O)3PCuI indicate an interradical exchange parameter J of −230 cm-1. ESR spectra of all three complexes show extremely broad, featureless lines as a result of very rapid spin−lattice relaxation. The reduction in exchange between the two halves of the bis(verdazyl) ligand upon coordination, and the unusual ESR properties, require a delocalized structure, with significant spin density on the copper atom. Variation of the auxiliary ligands on the copper atom allows tuning of the intramolecular exchange.
Publication Date
Publisher Statement
SJSU users: use the following link to login and access the article via SJSU databases
Citation Information
David J R Brook, Vincent Lynch, Brenda Conklin and Marye Anne Fox. "Spin delocalization in the Copper(I) Complexes of Bis(verdazyl) Diradicals" Journal of the American Chemical Society Vol. 119 Iss. 22 (1997)
Available at: