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Title: Temperature dependence of the spin state and geometry in tricobalt paddlewheel complexes with halide axial ligands

Abstract

Trinuclear cobalt paddlewheel complexes, [Co 3(dpa) 4X 2] (dpa = the anion of 2,2'-dipyridylamine, X = Cl–, Br–, –NCS–, –CN–, (NC) 2N–), are known to demonstrate a thermally-induced spin-crossover (SCO). Despite a wealth of structural and magnetic information about such complexes, the role of the axial ligand on the characteristic SCO temperature (T 1/2) remains ambiguous. The situation is complicated by the observation that the solid state geometry of the complexes, symmetric or unsymmetric, with respect to the central cobalt ion, also appears to influence the SCO behavior. In order to seek trends in the relationship between the nature of the axial ligand, geometry and magnetic properties, we have prepared the first examples of tricobalt paddlewheel complexes with axial fluorido and iodido ligands, as well as two new chlorido and bromido solvates. Their SCO properties are discussed in the context of an examination of previously reported chlorido and bromido adducts. The main conclusions are: (1) T 1/2 values follow the trend I– < Br– ≈ Cl– < F–; (2) while the molecular geometry is predominantly guided by crystal packing for the Cl–, Br– and I– derivatives, the presence of an axial fluoride may favor a more symmetric core; (3) themore » magnetic characterization of a second example of an unsymmetric complex supports the observation that they display dramatically lower T 1/2 values than their symmetric analogues; and (4) SCO in crystallographically symmetric compounds apparently occurs without loss of molecular or crystallographic symmetry, while a gradual geometric transformation linking the temperature dependence of quasi-symmetric to unsymmetric in crystallographically unconstrained compounds was found.« less

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [1];  [1]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [1]
  1. Centre National de la Recherche Scientifique (CNRS), Pessac (France). Centre de Recherche en Physique des Plasma (CRPP); Univ. of Bordeaux (France)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. of Zaragoza (Spain)
  4. Univ. of Oxford (United Kingdom)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1560410
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Dalton Transactions
Additional Journal Information:
Journal Volume: 47; Journal Issue: 46; Journal ID: ISSN 1477-9226
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Srinivasan, Anandi, Wang, Xiaoping, Clérac, Rodolphe, Rouzières, Mathieu, Falvello, Larry R., McGrady, John E., and Hillard, Elizabeth A. Temperature dependence of the spin state and geometry in tricobalt paddlewheel complexes with halide axial ligands. United States: N. p., 2018. Web. doi:10.1039/C8DT03833C.
Srinivasan, Anandi, Wang, Xiaoping, Clérac, Rodolphe, Rouzières, Mathieu, Falvello, Larry R., McGrady, John E., & Hillard, Elizabeth A. Temperature dependence of the spin state and geometry in tricobalt paddlewheel complexes with halide axial ligands. United States. doi:10.1039/C8DT03833C.
Srinivasan, Anandi, Wang, Xiaoping, Clérac, Rodolphe, Rouzières, Mathieu, Falvello, Larry R., McGrady, John E., and Hillard, Elizabeth A. Thu . "Temperature dependence of the spin state and geometry in tricobalt paddlewheel complexes with halide axial ligands". United States. doi:10.1039/C8DT03833C. https://www.osti.gov/servlets/purl/1560410.
@article{osti_1560410,
title = {Temperature dependence of the spin state and geometry in tricobalt paddlewheel complexes with halide axial ligands},
author = {Srinivasan, Anandi and Wang, Xiaoping and Clérac, Rodolphe and Rouzières, Mathieu and Falvello, Larry R. and McGrady, John E. and Hillard, Elizabeth A.},
abstractNote = {Trinuclear cobalt paddlewheel complexes, [Co3(dpa)4X2] (dpa = the anion of 2,2'-dipyridylamine, X = Cl–, Br–, –NCS–, –CN–, (NC)2N–), are known to demonstrate a thermally-induced spin-crossover (SCO). Despite a wealth of structural and magnetic information about such complexes, the role of the axial ligand on the characteristic SCO temperature (T1/2) remains ambiguous. The situation is complicated by the observation that the solid state geometry of the complexes, symmetric or unsymmetric, with respect to the central cobalt ion, also appears to influence the SCO behavior. In order to seek trends in the relationship between the nature of the axial ligand, geometry and magnetic properties, we have prepared the first examples of tricobalt paddlewheel complexes with axial fluorido and iodido ligands, as well as two new chlorido and bromido solvates. Their SCO properties are discussed in the context of an examination of previously reported chlorido and bromido adducts. The main conclusions are: (1) T1/2 values follow the trend I– < Br– ≈ Cl– < F–; (2) while the molecular geometry is predominantly guided by crystal packing for the Cl–, Br– and I– derivatives, the presence of an axial fluoride may favor a more symmetric core; (3) the magnetic characterization of a second example of an unsymmetric complex supports the observation that they display dramatically lower T1/2 values than their symmetric analogues; and (4) SCO in crystallographically symmetric compounds apparently occurs without loss of molecular or crystallographic symmetry, while a gradual geometric transformation linking the temperature dependence of quasi-symmetric to unsymmetric in crystallographically unconstrained compounds was found.},
doi = {10.1039/C8DT03833C},
journal = {Dalton Transactions},
number = 46,
volume = 47,
place = {United States},
year = {2018},
month = {11}
}

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Works referenced in this record:

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Cooperative phenomena and light-induced bistability in iron(II) spin-crossover compounds
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Molecular and Electronic Structures by Design:  Tuning Symmetrical and Unsymmetrical Linear Trichromium Chains
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Effects of Weak Intermolecular Interactions on the Molecular Isomerism of Tricobalt Metal Chains
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    Works referencing / citing this record:

    From Homonuclear Metal String Complexes to Heteronuclear Metal String Complexes: From Homonuclear to Heteronuclear Metal String Complexes
    journal, April 2015

    • Hua, Shao-An; Cheng, Ming-Chuan; Chen, Chun-hsien
    • European Journal of Inorganic Chemistry, Vol. 2015, Issue 15
    • DOI: 10.1002/ejic.201403237

    Tuning the Metal−Metal Bonds in the Linear Tricobalt Compound Co 3 (dpa) 4 Cl 2 :  Bond-Stretch and Spin-State Isomers
    journal, March 2001

    • Clérac, Rodolphe; Cotton, F. Albert; Daniels, Lee M.
    • Inorganic Chemistry, Vol. 40, Issue 6
    • DOI: 10.1021/ic001068i

    Compounds with Symmetrical Tricobalt Chains Wrapped by Dipyridylamide Ligands and Cyanide or Isothiocyanate Ions as Terminal Ligands
    journal, March 2001

    • Clérac, Rodolphe; Cotton, F. Albert; Jeffery, Stephen P.
    • Inorganic Chemistry, Vol. 40, Issue 6
    • DOI: 10.1021/ic001069a

    Linear Tricobalt Compounds with Di-(2-pyridyl)amide (dpa) Ligands:  Studies of the Paramagnetic Compound Co 3 (dpa) 4 Cl 2 in Solution
    journal, December 1999

    • Cotton, F. Albert; Murillo, Carlos A.; Wang, Xiaoping
    • Inorganic Chemistry, Vol. 38, Issue 26
    • DOI: 10.1021/ic990944t

    Molecular and Electronic Structures by Design:  Tuning Symmetrical and Unsymmetrical Linear Trichromium Chains
    journal, June 2004

    • Berry, John F.; Cotton, F. Albert; Lu, Tongbu
    • Journal of the American Chemical Society, Vol. 126, Issue 22
    • DOI: 10.1021/ja049055h

    A Three-State Model for the Polymorphism in Linear Tricobalt Compounds
    journal, March 2006

    • Pantazis, Dimitrios A.; McGrady, John E.
    • Journal of the American Chemical Society, Vol. 128, Issue 12
    • DOI: 10.1021/ja0581402

    Effects of Weak Intermolecular Interactions on the Molecular Isomerism of Tricobalt Metal Chains
    journal, June 2009

    • Poulsen, Rasmus D.; Overgaard, Jacob; Schulman, Alexander
    • Journal of the American Chemical Society, Vol. 131, Issue 22
    • DOI: 10.1021/ja8091032

    Symmetrical and Unsymmetrical Compounds Having a Linear Co 3 6+ Chain Ligated by a Spiral Set of Dipyridyl Anions
    journal, October 1997

    • Cotton, F. Albert; Daniels, Lee M.
    • Journal of the American Chemical Society, Vol. 119, Issue 43
    • DOI: 10.1021/ja971997h

    Structural and magnetic properties of Co3(dpa)4Br2 †
    journal, January 2001

    • Clérac, Rodolphe; Cotton, F. Albert; Daniels, Lee M.
    • Journal of the Chemical Society, Dalton Transactions, Issue 4
    • DOI: 10.1039/b007876j