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Synthesis, characterization, and electrochemistry of SNS cobalt(II) tridentate complexes


The preparation of two cobalt(II) complexes that contain a tridentate ligand with sulfur, nitrogen, and sulfur donor atoms is described. The tridentate ligand precursors are based on bis-imidazole or bis-triazole moieties. The complex based on a bis-imidazole precursor was green in color and was prepared in 93.3% yield. The complex based on a bis-triazole precursor was blue-green in color and was prepared in 69.8% yield. Single-crystal structures of both complexes were obtained. Both complexes contain [BF4] as the counter-anion. Based on the single-crystal structure, the molecular geometry around the cobalt(II) center is distorted tetrahedral. EPR spectra were obtained for both complexes at 4 K. Each complex has axial symmetry for its electron density and each cobalt(II) complex has S = 3/2. For the complex based on a bis-imidazole precursor, the UV–Vis peaks were observed at 696 nm, 629 nm, 585 (sh) nm, and 375 (sh) nm. For the complex based on bis-triazole, UV–Vis peaks were observed at 681, 613, 570, 243, 239, 236, 233, 230, 227, and 210 nm. Cyclic voltammetry spectra were obtained for both complexes. Both the ligand precursor and the cobalt(II) complexes are redox active. All of the redox waves were irreversible.

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Data availability

The data are stored on Dropbox and on computers at Fairfield University. The CIF files have been deposited with the Cambridge Structure Database.


  1. Peris E, Crabtree RH (2018) Key factors in ligand pincer design. Chem Soc Rev 47:1959–1968

    CAS  Article  Google Scholar 

  2. Gunanathan C, Milstein D (2014) Bond activation and catalysis by ruthenium pincer complexes. Chem Rev 114:12024–12087

    CAS  Article  Google Scholar 

  3. Szabo KJ, Wendt OF (eds) (2014) Pincer and Pincer-type complexes: applications in organic synthesis and catalysis. Wiley VCH, Weinheim

    Google Scholar 

  4. van Koten G, Milstein D (eds) (2013) Organometallic pincer complexes. Springer, Berlin

    Google Scholar 

  5. van Koten G, Gossage RA (2015) The privileged Pincer-Metal Platform: coordination chemistry & applications. Springer, Berlin

    Google Scholar 

  6. Miecznikowski JR, Lo W, Lynn MA, O’Loughlin BE, DiMarzio AP, Martinez AM, Lampe L, Foley KM, Keilich LC, Lisi GP, Kwiecien DJ, Pires CM, Kelly WJ, Kloczko NF, Morio KN (2011) Syntheses, characterization, density functional theory calculations, and activity of tridentate SNS zinc pincer complexes. Inorg Chim Acta 376:515–524

    CAS  Article  Google Scholar 

  7. Miecznikowski JR, Lo W, Lynn MA, Jain S, Keilich LC, Kloczko NF, O’Loughlin BE, DiMarzio AP, Foley KM, Lisi GP, Kwiecien DJ, Butrick EE, Powers E, Al-Abbasee R (2012) Syntheses, characterization, density functional theory calculations, and activity of tridentate SNS Zinc Pincer Complexes Based on Bis-Imidazole or Bis-Triazole Precursors. Inorg Chim Acta 387:25–36

    CAS  Article  Google Scholar 

  8. Holm RH, Kennepohl P, Solomon EI (1996) Structural and functional aspects of metal sites in biology. Chem Rev 96:2239–2314

    CAS  Article  Google Scholar 

  9. Miecznikowski JR, Lynn MA, Jasinski JP, Lo W, Bak D, Pati M, Butrick EE, Drozdoski AER, Archer KA, Villa CE, Lemons EG, Powers E, Siu M, Gomes CD, Bernier NA, Morio KN (2014) Synthesis and characterization of three-and five-coordinate copper(II) complexes based on SNS pincer ligand precursors. Polyhedron 80:157–165

    CAS  Article  Google Scholar 

  10. Miecznikowski JR, Lynn MA, Jasinski JP, Reinheimer E, Bak D, Pati M, Butrick EE, Drozdoski AER, Archer KA, Villa CE, Lemons EG, Powers E, Siu M, Gomes CD, Morio KN (2014) “Synthesis, characterization, and computational study of three-coordinate SNS copper(I) complexes based on bis-thione ligand precursors. J Coord Chem 67:29–44

    CAS  Article  Google Scholar 

  11. Lynn MA, Miecznikowski JR, Jasinski JP, Kaur M, Mercado BQ, Reinheimer E, Almanza E, Kharbouch RM, Smith MR, Zygmont SE, Flaherty NF, Smith AC (2019) Copper(I) SNS Pincer complexes: impact of ligand design and solvent coordination on conformer interconversion from spectroscopic and computational studies. Inorg Chim Acta 495.

  12. Mast Z, Huntzinger CG, Stinson TA, Myren THT, Kharbouch RM, Almanza EM, Zygmont SE, Miecznikowski JR, Luca OR (2020) Cu(I) SNS triazole and imidazole pincers as electrocatalyst precursors for solar fuel production. Inorganic Chem Front 7:1012–1015

    CAS  Article  Google Scholar 

  13. Miecznikowski JR, Mircovich EE, Bertolotti NR et al (2022) Synthesis, single crystal structure and spectroscopic characterization of a Nickel(II) complex that contains a SNS tridentate ligand. J Chem Crystallogr.

  14. Jia W-G, Dai Y-C, Zhang H-N, Lu X, Sheng EH (2015) Synthesis and characterization of gold complexes with pyridine based SNS ligands and as homogenous catalysts for the reduction of 4-nitrophenol. RSC Adv 5(37):29491–29496

    CAS  Article  Google Scholar 

  15. Jia W-G, Huang YB, Jin GX (2009) Synthesis, characterization of novel half-sandwich iridium and rhodium complexes containing pyridine-based organochalcogen ligands. J Organomet Chem 694(25):4008–4013

    CAS  Article  Google Scholar 

  16. Katam S, Ganesan P (2017) Large CuI8 chalcogenone cubic cages with non-interacting counter ions. Dalton Trans 46(47):16615–16622

    CAS  Article  Google Scholar 

  17. Sun Y, Wang H, Jia W-G (2015) Crystal structure of 3,3-disopropyl-1,1’-(pyridine-2,6-diyl)bis[1H-imidazole-2(3H)-thione]. Acta Crystallogr E 71(4):o255.

  18. Gridnev AA, Mihaltseva IM (1994) Synthesis of 1-alkylimidazoles. Synth Commun 24(11):1547–1555

    CAS  Article  Google Scholar 

  19. Petasis DT, Hendrich MP (2015) Chapter Eight - quantitative interpretation of multifrequency multimode EPR spectra of metal containing proteins, enzymes, and biomimetic complexes. In: Qin PZ, Warncke K (eds) Methods enzymol. Academic Press, New York, vol 563, pp 171–208

  20. Dolomanov OV, Bourhis LJ, Gildea RJ, Howard JAK, Puschmann H (2009) OLEX2: a complete structure solution, refinement and analysis program. J Appl Crystallogr 42(2):339–341

    CAS  Article  Google Scholar 

  21. Sheldrick., (2015) SHELXT - Integrated space-group and crystal-structure determination. Acta Crystallogr Sect A 71 (1):3–8.

  22. Sheldrick G (2015) Crystal structure refinement with SHELXL. Acta Crystallogr C 71(1):3–8

    Article  Google Scholar 

  23. Miecznikowski JR, Jasinski JP, Bonitatibus SC, Almanza E, Kharbouch RM, Zygmont SE, Landy KR (2020) Preparation of SNS cobalt(II) pincer model complexes of liver alcohol dehydrogenase. J Vis Exp 157:e60668.

    CAS  Article  Google Scholar 

  24. Yang L, Powell DR, Houser RP (2007) Structural variation in copper(I) complexes with pyridylmethylamide ligands: structural analysis with a new four-coordinate geometry index, τ4. Dalton Trans 9:955–964

    Article  Google Scholar 

  25. Trzhtsinskaya BV, Abramova ND (1991) Imidazole-2-Thiones: synthesis, structure, properties. Sulfur Reports 10(4):389–421

    CAS  Article  Google Scholar 

  26. Kouichi F, Hiroaki O-H, Noboru H (1991) ESR and magnetic susceptibility studies on high-spin tetrahedral cobalt(II) Thiolate complexes: an approach to rubredoxin-type active sites. Bull Chem Soc Jpn 64(4):1205–1212

    Article  Google Scholar 

  27. Poutney DL, Vasak M (1992) Spectroscopic studies on metal distribution in Co(II)/Zn(II) mixed-metal clusters in rabbit liver metallothionein 2. Eur J Biochem 209:335–341

    Article  Google Scholar 

  28. Werth MT, Tang S, Formicka G, Zeppezauer M, Johnson MK (1995) Magnetic circular dichroism and electron paramagnetic resonance studies of cobalt-substituted horse liver alcohol dehydrogenase. Inorg Chem 34:218–228

    CAS  Article  Google Scholar 

  29. Maret W, Andersson I, Dietrich H, Schneider-Bernlohr H, Einarsson R, Zeppezauer M (1979) Site-Specific substituted cobalt(II) horse liver alcohol dehydrogenases. Eur J Biochem 98(2):501–512

    CAS  Article  Google Scholar 

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JRM acknowledges the National Science Foundation Major Research Instrumentation Program for the purchases of an EPR spectrometer (CHE-08539), X-ray diffractometer (CHE-1039027), and a 400 MHz NMR Spectrometer (CHE-1827854). JRM is grateful for receiving generous support from the NASA CT Space Grant (Award number P-1168) in support of this work. EMA, RMK, SCB, SEZ, and EEM received Hardiman Research Scholarships when working on this project at Fairfield University. ACW and SCB are supported by NIH award (R01-GM110390).


John Miecznikowski has received funding from the National Science Foundation (CHE-08539 and CHE-1827854), NASA Connecticut Space Grant (P-1168), and Fairfield University in support of this work. John Miecznikowski is employed by Fairfield University and has a visiting appointment in the Department of Chemistry at Yale University. John Miecznikowski has served on review panels at the National Science Foundation. Jerry Jasinski has received funding from the National Science Foundation (CHE-1039027) which supported this work. Jerry Jasinski was employed by Keene State College when the work was performed. Samantha Zygmont, Sheila Bonitatibus, Emilse Almanza, Rami Kharbouch, and Emma Mircovich were supported by Fairfield University (Hardiman Scholarship) when the work was performed. Eric Reinheimer and Pierre LeMageres are employed by Rigaku Corporation Americas. Andrew Weitz is a post-doctoral fellow at Boston University and is supported by a grant from the NIH (R01-GM110390). Sheila Bonitatibus is also supported by (R01-GM110390).

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JM contributed to conceptualization, writing original draft, writing review and editing, visualization, supervision, project administration, and funding acquisition; SZ and SB contributed to investigation, validation, visualization, and writing original draft; JPJ and MK contributed to investigation; EA, RK, and EM contributed to investigation and validation; PLM and ER contributed to investigation and visualization; AW contributed to investigation, visualization, and revising draft.

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Correspondence to John R. Miecznikowski.

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This article is dedicated to Professor Jerry P. Jasinski, a great collaborator and friend.

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Miecznikowski, J.R., Zygmont, S.E., Jasinski, J.P. et al. Synthesis, characterization, and electrochemistry of SNS cobalt(II) tridentate complexes. Transit Met Chem 47, 127–137 (2022).

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