| Abstract
| - 1,1‘,5,5‘-tetramethyl-6,6‘-dioxobis(verdazyl) (BVD) reactswith copper(I) halides in acetonitrile andcopper(II) halides in methanol to give copper(I) coordination polymers ofcomposition[Cu2X2(BVD)]x.When X = Cl andX = Br, these polymers crystallize in orthorhombic unit cells withdimensions 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 dimensionsa = 12.669 Å, b = 8.461 Å, c =7.679 Å, andβ = 91.88°, although poor crystal quality prevented a fullstructure determination. Magnetic susceptibilitymeasurements taken on the three polymers indicate that the spins couplein one-dimensional chains with alternatingexchange parameters: J1 = −190cm-1, J2 = −116cm-1 (X = Cl); J1= −200 cm-1, J2= −110 cm-1 (X = Br);and J1 = −271cm-1, J2 = −200cm-1 (X = I). Variable temperature ESRmeasurements on the unstable monomericcomplex resulting from reaction of BVD with(CH3O)3PCuI indicate an interradicalexchange parameter J of −230cm-1. ESR spectra of all three complexesshow extremely broad, featureless lines as a result of very rapidspin−lattice relaxation. The reduction in exchange between the twohalves of the bis(verdazyl) ligand upon coordination,and the unusual ESR properties, require a delocalized structure, withsignificant spin density on the copper atom.Variation of the auxiliary ligands on the copper atom allowstuning of the intramolecular exchange.
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