Electronic Structure of a Paramagnetic {MNO}[superscript 6] Complex: MnNO 5,5-Tropocoronand
Name
Tangen et al Inorg chem.pdf
Size
2.84 MB
Format
Adobe PDF
Checksum (MD5)
8e2753e10b6358200d2ddcfca3d10ba0
Author(s)
Tangen, Espen
Conradie, Jeanet
Franz, Katherine
Friedle, Simone
Telser, Joshua
Lippard, Stephen J.
Ghosh, Abhik
Alternative Title
Electronic Structure of a Paramagnetic {MNO}6 Complex: MnNO 5,5-Tropocoronand
Date Issued
February 2010
Journal
Inorganic Chemistry
Publisher
American Chemical Society
Citation
Tangen, Espen et al. “Electronic Structure of a Paramagnetic {MNO}6 Complex: MnNO 5,5-Tropocoronand.” Inorganic Chemistry 49.6 (2010) : 2701-2705.
Version
Author's final manuscript
Abstract
Using density functional theory (OLYP/STO-TZP) calculations, we have investigated the electronic structure of [Mn(5,5-tropocoronand)(NO)], a rare paramagnetic {MNO}6 complex. Experimental methods, including magnetic susceptibility measurements and high-field electron paramagnetic resonance spectroscopy, have not provided an unambiguous spin state assignment for this complex. In other respects, however, the compound was fully characterized, including by means of single-crystal X-ray structure determination. The optimized S = 1 OLYP geometry reproduced all key aspects of the trigonal-bipyramidal molecular structure, including a short Mn-N(O) distance (∼1.7 A° ) and an essentially linear MnNO angle. In contrast, the S = 0 and S = 2 optimized structures disagreed with the crystal structure in critical respects. Moreover, three different exchange-correlation functionals (OLYP, B3LYP, and B3LYP*) indicated an S = 1 ground state by a clear margin of energy. An examination of the Kohn-Sham MOs of this state indicated a primarily dxz 2dyz 2dxy 1dx2-z2 1 electronic configuration, where the z axis is identified with the nearly linear MnNO axis. The dy2 orbital is formally unoccupied in this state, interacting, as it does, head-on with two tropocoronand nitrogens lying along the y axis, the pseudo-3-fold axis of the trigonal bipyramid. The doubly occupied dxz and dyz orbitals are in actuality dπ(Fe)-pi*(NO)-based pi-bonding molecular orbitals, the R and β “components” of which are significantly offset spatially. This offset results in excess minority spin density on the NO unit. Thus, the OLYP/TZP atomic spin populations are Mn, 2.85; N(O), -0.52; and O, -0.35.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1021/ic901860x
