ACS Publications. Most Trusted. Most Cited. Most Read
My Activity

Figure 1Loading Img

Facile Thermal W–W Bond Homolysis in the N-Heterocyclic Carbene Containing Tungsten Dimer [CpW(CO)2(IMe)]2

View Author Information
Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, United States
Cite this: Organometallics 2012, 31, 5, 1775–1789
Publication Date (Web):February 8, 2012
Copyright © 2012 American Chemical Society

    Article Views





    Read OnlinePDF (2 MB)
    Supporting Info (2)»


    Abstract Image

    The thermal W–W bond homolysis in [CpW(CO)2(IMe)]2 (IMe = 1,3-dimethylimidazol-2-ylidene) was investigated and was found to occur to a large extent in comparison to other tungsten dimers such as [CpW(CO)3]2. CpW(CO)2(IMe)H was prepared by heating a solution of [IMeH]+[CpW(CO)2(PMe3)], and it exists in solution as a mixture of interconverting cis and trans isomers. The carbene rotation in CpW(CO)2(IMe)H was explored by DFT calculations, and low enthalpic barriers (<3.5 kcal mol–1) are predicted. CpW(CO)2(IMe)H has pKaMeCN = 31.5(3), and deprotonation with KH gives K+[CpW(CO)2(IMe)] (·MeCN). Hydride abstraction from CpW(CO)2(IMe)H with Ph3C+PF6 in the presence of a coordinating ligand L (MeCN or THF) gives [CpW(CO)2(IMe)(L)]+PF6. Electrochemical measurements on the anion [CpW(CO)2(IMe)] in MeCN, together with digital simulations, give an E1/2 value of −1.54(2) V vs Cp2Fe+/0 for the [CpW(CO)2(IMe)]•/– couple. A thermochemical cycle provides the solution bond dissociation free energy of the W–H bond of CpW(CO)2(IMe)H as 61.3(6) kcal mol–1. In the electrochemical oxidation of [CpW(CO)2(IMe)], reversible dimerization of the electrogenerated radical CpW(CO)2(IMe) occurs, and digital simulation provides kinetic and thermodynamic parameters for the monomer–dimer equilibrium: kdimerization ≈ 2.5 × 104 M–1 s–1, khomolysis ≈ 0.5 s–1 (i.e., Kdim ≈ 5 × 104 M–1). Reduction of [CpW(CO)2(IMe)(MeCN)]+PF6 with cobaltocene gives the dimer [CpW(CO)2(IMe)]2, which in solution exists as a mixture of anti and gauche rotamers. As expected from the electrochemical experiments, the dimer is in equilibrium with detectable amounts of CpW(CO)2(IMe). This species was observed by IR spectroscopy, and its presence in solution is also in accordance with the observed reactivity toward 2,6-di-tert-butyl-1,4-benzoquinone, chloroform, and dihydrogen.

    Supporting Information

    Jump To

    Text, tables, figures, and CIF files giving details of the synthesis of [IMeH]+[CpW(CO)3], discussion of C–H···O interactions in the crystal structure of [IMeH]+[CpW(CO)2(PMe3)], atomic coordinates and other details for calculations on CpW(CO)2(IMe)H, procedures, data, and plots relevant to the cis–trans equilibrium of CpW(CO)2(IMe)H, solid-state and solution IR spectra and 1H NMR spectra of [CpW(CO)2(IMe)]2, and crystallographic data. This material is available free of charge via the Internet at

    Terms & Conditions

    Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system:

    Cited By

    This article is cited by 20 publications.

    1. Ming-Yue Ju, Zi-Heng Fan, Yubin Ma, Yi Jing, Xi-Meng Chen, Xuenian Chen. Syntheses, Structures, and Reactivities of N-Heterocyclic Carbene-Coordinated Aminoborane Complexes. Inorganic Chemistry 2023, 62 (22) , 8700-8709.
    2. Jocelyn Sinclair, Guoliang Dai, Robert McDonald, Michael J. Ferguson, Alex Brown, Eric Rivard. Insight into the Decomposition Mechanism of Donor–Acceptor Complexes of EH2 (E = Ge and Sn) and Access to Germanium Thin Films from Solution. Inorganic Chemistry 2020, 59 (15) , 10996-11008.
    3. Tao Huang, Eric S. Rountree, Andrew P. Traywick, Magd Bayoumi, Jillian L. Dempsey. Switching between Stepwise and Concerted Proton-Coupled Electron Transfer Pathways in Tungsten Hydride Activation. Journal of the American Chemical Society 2018, 140 (44) , 14655-14669.
    4. Zeping Hui, Takahito Watanabe, and Hiromi Tobita . Synthesis of Base-Stabilized Hydrido(hydroborylene)tungsten Complexes and Their Reactions with Terminal Alkynes To Give η3-Boraallyl Complexes. Organometallics 2017, 36 (24) , 4816-4824.
    5. Huayi Fang, Huize Jing, Haonan Ge, Penelope J. Brothers, Xuefeng Fu, and Shengfa Ye . The Mechanism of E–H (E = N, O) Bond Activation by a Germanium Corrole Complex: A Combined Experimental and Computational Study. Journal of the American Chemical Society 2015, 137 (22) , 7122-7127.
    6. Elena A. Giner, Alicia Santiago, Mar Gómez-Gallego, Carmen Ramírez de Arellano, Rebecca C. Poulten, Michael K. Whittlesey, and Miguel A. Sierra . Mono- and Bimetallic Zwitterionic Chromium(0) and Tungsten(0) Allenyls. Inorganic Chemistry 2015, 54 (11) , 5450-5461.
    7. Stéphane Bellemin-Laponnaz and Samuel Dagorne . Group 1 and 2 and Early Transition Metal Complexes Bearing N-Heterocyclic Carbene Ligands: Coordination Chemistry, Reactivity, and Applications. Chemical Reviews 2014, 114 (18) , 8747-8774.
    8. Edwin F. van der Eide, Gao-Lei Hou, S. H. M. Deng, Hui Wen, Ping Yang, R. Morris Bullock, and Xue-Bin Wang . Metal-Centered 17-Electron Radicals CpM(CO)3• (M = Cr, Mo, W): A Combined Negative Ion Photoelectron Spectroscopic and Theoretical Study. Organometallics 2013, 32 (7) , 2084-2091.
    9. Edwin F. van der Eide, Monte L. Helm, Eric D. Walter, and R. Morris Bullock . Structural and Spectroscopic Characterization of 17- and 18-Electron Piano-Stool Complexes of Chromium. Thermochemical Analyses of Weak Cr–H Bonds. Inorganic Chemistry 2013, 52 (3) , 1591-1603.
    10. Gang Li, Arthur Han, Mary E. Pulling, Deven P. Estes, and Jack R. Norton . Evidence for Formation of a Co–H Bond from (H2O)2Co(dmgBF2)2 under H2: Application to Radical Cyclizations. Journal of the American Chemical Society 2012, 134 (36) , 14662-14665.
    11. Paul J. Fischer, Michelle C. Neary, Laura Avena, Kevin P. Sullivan, and Kent C. Hackbarth . Dicarbonyl{[2-(diphenylphosphino)ethyl]cyclopentadienyl} Group VI Metal Hydrides, Halides, and Anions: Precursors for Olefin Epoxidation Catalysts. Organometallics 2012, 31 (6) , 2437-2444.
    12. Günther Horrer, Martin S. Luff, Udo Radius. N-Heterocyclic carbene and cyclic (alkyl)(amino)carbene ligated half-sandwich complexes of chromium( ii ) and chromium( i ). Dalton Transactions 2023, 52 (37) , 13244-13257.
    13. Christian Luz, Eduard Glok, Günther Horrer, Udo Radius. N-heterocyclic carbene and cyclic (alkyl)(amino)carbene complexes of molybdenum( iv ) and tungsten( iv ). Dalton Transactions 2022, 51 (47) , 18337-18352.
    14. Satoshi Takebayashi, Robert R. Fayzullin, Richa Bansal. Direct observation of reversible bond homolysis by 2D EXSY NMR. Chemical Science 2022, 13 (32) , 9202-9209.
    15. Philipp M. Hauser, Felix Ziegler, Janis V. Musso, Pradeep K.R. Panyam, Mohasin Momin, Jonas Groos, Michael R. Buchmeiser. N-Heterocyclic and Mesoionic Carbene Complexes of Group 5 and Group 6 Metals. 2022, 208-263.
    16. Peter M. Graham. Tungsten. 2021, 746-806.
    17. S. S. Shapovalov, O. G. Tikhonova, M. O. Grigor’eva, I. V. Skabitskii, N. P. Simonenko. Metal Complexes with the N-Heterocyclic Ligand: Synthesis, Structures, and Thermal Decomposition. Russian Journal of Coordination Chemistry 2019, 45 (10) , 706-711.
    18. Yusuke Sunada, Shintaro Ishida, Fumiya Hirakawa, Yoshihito Shiota, Kazunari Yoshizawa, Shinji Kanegawa, Osamu Sato, Hideo Nagashima, Takeaki Iwamoto. Persistent four-coordinate iron-centered radical stabilized by π-donation. Chemical Science 2016, 7 (1) , 191-198.
    19. Zhe Wang, Lu Jiang, Dara Khairunnisa Binte Mohamed, Jin Zhao, T.S. Andy Hor. N-heterocyclic carbene complexes of Group 6 metals. Coordination Chemistry Reviews 2015, 293-294 , 292-326.
    20. Xiayan Zhang, Decheng Meng, Xiaoyan Li, Lingpeng Meng, Zheng Sun. Nature of the M–M bonding (M = Cr, Mo, and W) in [CpM(CO)3]2: Covalent single bond or noncovalent interaction?. Journal of Organometallic Chemistry 2014, 769 , 106-111.

    Pair your accounts.

    Export articles to Mendeley

    Get article recommendations from ACS based on references in your Mendeley library.

    Pair your accounts.

    Export articles to Mendeley

    Get article recommendations from ACS based on references in your Mendeley library.

    You’ve supercharged your research process with ACS and Mendeley!

    STEP 1:
    Click to create an ACS ID

    Please note: If you switch to a different device, you may be asked to login again with only your ACS ID.

    Please note: If you switch to a different device, you may be asked to login again with only your ACS ID.

    Please note: If you switch to a different device, you may be asked to login again with only your ACS ID.

    Your Mendeley pairing has expired. Please reconnect