Experimental and computational studies of binding of dinitrogen, nitriles, azides, diazoalkanes, pyridine, and pyrazines to M(PR3) 2(CO)3 (M = Mo, W.; R = Me, Pr)

Patrick Achord, Etsuko Fujita, James Muckerman, Brian Scott, George C. Fortman, Manuel Temprado, Xiaochen Cai, Burjor Captain, Derek Isrow, John J. Weir, James Eric McDonough, Carl D. Hoff

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Abstract

The enthalpies of binding of a number of N-donor ligands to the complex Mo(PiPr3)2(CO)3 in toluene have been determined by solution calorimetry and equilibrium measurements. The measured binding enthalpies span a range of ∼10 kcal mol-1: δH binding = -8.8±1.2 (N2-Mo(PiPr 3)2(CO)3); -10.3 ±0.8 (N2); -11.2 ±0.4 (AdN3 (Ad = 1 -adamantyl)); -13.8± 0.5 (N2CHSiMe3); -14.9 ± 0.9 (pyrazine=pz); -14.8 ± 0.6 (2,6-Me2pz); -15.5 ± 1.8 (Me2NCN); -16.6 ± 0.4 (CH3CN); -17.0 ± 0.4 (pyridine); -17.5 ± 0.8 ([4-CH3pz][PF6] (in tetrahydrofuran)); -17.6 ± 0.4 (C6H5CN); -18.6 ± 1.8 (N 2CHC (=O)OEt); and -19.3 ± 2.5 kcal moP-1 (pz)Mo(PiPr3)2(CO)3). The value for the isonitrile AdNC (-29.0 ± 0.3) is 12.3 kcal mol-1 more exothermic than that of the nitrile AdCN (- 16.7 ± 0.6 kcal mol -1). The enthalpies of binding of a range of arene nitrile ligands were also studied, and remarkably, most nitrile complexes were clustered within a 1 kcal mol-1 range despite dramatic color changes and variation of VCN- Computed structural and spectroscopic parameters for the complexes Mo (PiPr3)2(CO)3L are in good agreement with experimental data. Computed binding enthalpies for Mo(P iPr3)2(CO)3L exhibit considerable scatter and are generally smaller compared to the experimental values, but relative agreement is reasonable. Computed enthalpies of binding using a larger basis set for Mo(PMe3)2(CO)3L show a better fit to experimental data than that for Mo(PiPr3) 2(CO)3L using a smaller basis set. Crystal structures of Mo(PiPr3)2(CO)3(AdCN), W(P iPr3)2(CO)3(Me2NCN), W (PiPr3)2(CO)3(2,6-F 2C6H3CN), W(PiPr3) 2(CO)3(2,4,6-Me3C6H2CN), W(PiPr3)2(CO)3(2,6-Me 2pz), W(P'Pr3)2(CO)3(AdCN), Mo(PiPr3)2(CO)3(AdNC), and W(P iPr3)2(CO)3(AdNC) are reported.

Original languageEnglish
Pages (from-to)7891-7904
Number of pages14
JournalInorganic Chemistry
Volume48
Issue number16
DOIs
Publication statusPublished - Aug 17 2009

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ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

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Achord, P., Fujita, E., Muckerman, J., Scott, B., Fortman, G. C., Temprado, M., Cai, X., Captain, B., Isrow, D., Weir, J. J., McDonough, J. E., & Hoff, C. D. (2009). Experimental and computational studies of binding of dinitrogen, nitriles, azides, diazoalkanes, pyridine, and pyrazines to M(PR3) 2(CO)3 (M = Mo, W.; R = Me, Pr). Inorganic Chemistry, 48(16), 7891-7904. https://doi.org/10.1021/ic900764e