ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Recent results concerning synthetic, structural, and magnetic work on 3,4,9,10-perylenetetracarboxylic acid complexes of copper (II) are discussed. To date, the Cu(II)/PTCA/dien system has yielded two compositionally different crystalline products. Compound 1, [Cu3(dien)3(PTCA)(H2O)3](ClO4)22H2O represents the extremely rare case of three different molecular complexes of Cu(II), bound to the same ligands but with different stoichiometries, in the same compound. The magnetic lattice is comprised of three molecular substructures: complex 1a is a monomeric cation, [Cu(dien)(H2O)2]2+; complex 1b is a charge-neutral dimer, [Cu2(dien)2-(PTCA)(H2O)2]; and complex 1c a charge-neutral, infinite ladder-like chain structure, ∞1[Cu2(dien)2(PTCA)]n. Single crystal x-ray analysis of compound 2, [Cu2(dien)2(PTCA)(H2O)2]12H2O, reveals its structure simply consists of isolated, neutral dimers similar in structure to complex 1b. Magnetic susceptibility data in the temperature range 1.7–300 K shows the dimeric unit in 2 to be a weakly exchange-coupled antiferromagnetic dimer (−0.6 cm−1) and suggests that exchange interactions are indeed propagated through the PTCA anion over a Cu.....Cu separation of 15.7 A(ring). This result, in addition to the expected Curie paramagnetism of monomer 1a, affords the ladder-like chain 1c to be characterized as a chain of antiferromagnetically exchange-coupled ferromagnetic dimers (+12 cm−1). Long range ordering is not observed down to 1.7 K. Compound 1 is the first example of a molecular-based magnetic material that contains three different homonuclear magnetic molecules; a monomer, a dimer, and a ladder-like chain.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.354774
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