Structural, Magnetic, and Charge-Transport Properties of a New One-Dimensional Molecular Conductor, Ni(tprpc)I1.67 (tprpc = 2,7,12,17-Tetrapropylporphycenato)
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Chemical oxidation of (2,7,12,17-tetrapropylporphycenato)nickel(II), Ni(tprpc), with iodine affords the new onedimensional molecular conductor Ni(tprpc)I1.67· The compound is composed of partially oxidized (+1/3) Ni(tprpc) cations packed in a slip-stack manner along the b axis. The stacks are surrounded by disordered chains of iodine, identified as I5- by Raman spectroscopy. The interplanar distance between Ni(tprpc) macrocycles is 3.306(10) Å, but the Ni-Ni distance is the b axis repeat distance, 4.982(1) Å. The conductivity measured along the needle (crystallographic b) axis of a single crystal is 2.5 × 10-2Ω-1 cm-1 at room temperature and may be fit to the expression σ= σ0 exp(-ΔE/kBT) (σ0 ≈ 1, ΔE= 0.15(2) eV). EPR measurements confirm that the tprpc ligand is oxidized. The compound crystallizes in space group C62h-C2/c of the monoclinic system with four formula units (C32H36- I1.67N4Ni) in a cell of a = 22.548(5) Å, b = 4.982(1) Å, c = 27.156(5) Å, β = 109.51(3)° (K= 2875.4(10) Å3) at 108 K. The structure has been refined on F2(2923 unique reflections) to Rw(F02) = 0.209. The conventional agreement index R(F) is 0.099 for the 1240 reflections having F02 > 2σ(F02). The relatively high R index results from our inability to model adequately the disordered iodine chains. © 1994, American Chemical Society. All rights reserved.
author list (cited authors)
Miller, D. C., Bollinger, J. C., Hoffman, B. M., & Ibers, J. A.