American Chemical Society
jp104954w_si_002.cif (35.77 kB)

Structural Analysis and Electronic Properties of Negatively Charged TCNQ: 2D Networks of (TCNQ)2Mn Assembled on Cu(100)

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posted on 2010-10-14, 00:00 authored by X. Q. Shi, Chensheng Lin, C. Minot, Tzu-Chun Tseng, Steven L. Tait, Nian Lin, R. Q. Zhang, Klaus Kern, J. I. Cerdá, M. A. Van Hove
A compound two-dimensional monolayer mixing Mn atoms and 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecules was synthesized by supramolecular assembly on a Cu(100) surface under ultrahigh-vacuum conditions. The interactions in the Mn(TCNQ)2 network and in the full system are analyzed from a molecular orbital perspective and in the light of scanning tunneling microscopy (STM) imaging and simulations. Structural, electronic, and magnetic properties are studied in detail using density functional theory (DFT) calculations. In the absence of Cu and depending on the theoretical method used, the TCNQ species can be formally described as either dianions TCNQ2− interacting with Mn4+ cations according to ligand field theory (using GGA calculations) or, alternatively, as radical monoanions interacting with Mn2+ cations in a high spin state (using GGA+U calculations). In the complete system including a Cu substrate, whatever theoretical method is used, TCNQs appear as dianions interacting with both Mn2+ cations in a high spin state (d5) and charged copper surface atoms.