Supporting Information. A New FeMo complex as model of heterobimetallic assemblies in natural systems: Mössbauer and DFT investigations

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1 1 Supporting Information A New FeMo complex as model of heterobimetallic assemblies in natural systems: Mössbauer and DFT investigations Solène Bouchard, Martin Clémancey,, Geneviève Blondin,*,& Maurizio Bruschi,* Kévin Charreteur, Luca De Gioia, Christine Le Roy, François Y. Pétillon, Philippe Schollhammer,* Jean Talarmin UMR CNRS 6521, Université de Bretagne Occidentale, Brest, France CEA, irtsv-lcbm-pmb, 17 rue des Martyrs, Grenoble, France Univ. Grenoble Alpes, irtsv-lcbm-pmb, 17 rue des Martyrs, Grenoble, France & CNRS, irtsv-lcbm-pmb, 17 rue des Martyrs, Grenoble, France Department of Biotechnology and Bioscience, University of Milano-Bicocca, Piazza della Scienza 2, Milan, Italy. Department of Earth and Environmental Sciences, University of Milano-Bicocca, Piazza della Scienza 1, Milan, Italy.

2 2 Table of contents Methods and material 3 Synthesis of [FeMo(CO) 5 ( 2 -dppe)(μ-pdt)] (1).. 3 DFT calculations 4 Figure S1. IR spectrum of 1 in CH 2 Cl 2 (carbonyl region). 6 Figure S2. 31 P{ 1 H} NMR spectrum of 1 in CDCl 3..7 Figure S3. 1 H NMR spectrum of 1 in CDCl 3..8 Figure S4. COSY 1 H- 1 H NMR spectrum of 1 in CDCl Figure S5. 13 C{ 1 H} NMR spectrum of 1 in CDCl Figure S6. 13 C{ 1 H} NMR spectrum (CO and C 6 H 5 region) of 13 C-labeled complex 1 in CDCl Figure S7. 31 P{ 1 H} NMR spectrum of 13 C-labeled complex 1 in CDCl Figure S8. IR spectra of 1 (red trace) and 13 C-labeled complex 1 (blue trace) in CH 2 Cl 2 (carbonyl region)...13 Figure S9. Calculated IR spectrum of 1 using the BP86/TZVP computational scheme Figure S10. Charge partitioning scheme of 1 and 2 15 Figure S11. Orbital diagram and relevant frontier molecular orbitals of the [FeMo(CO) 5 ( 2 -dppe)(μ-pdt)] complex (1) Figure S12. Orbital diagram and relevant frontier molecular orbitals of the [Fe(CO) 2 (PMe 3 )(µ-pdt)fe(pme 3 )(CO) 2 ] complex (2)...17 Figure S13. Schematic representation of the calculated structures of 2 and 2 + with selected geometrical parameters Figure S14. Cyclic voltammetry of [FeMo(CO) 5 ( 2 -dppe)(μ-pdt)] (1, 1.03 mm) in CH 2 Cl 2 [NBu 4 ][PF 6 ].. 19 Figure S15 Scan rate dependence of the current functions for the oxidation and for the reduction of 1 (1.34 mm) in CH 2 Cl 2 [NBu 4 ][PF 6 ]..20 Table S1. Experimental and calc. Mössbauer parameters for Table S2. Calculated Mössbauer parameters of 2 and Table S3. Atomic contribution to the electron population of relevant MOs in 1 and Table S4. DFT calculated cartesian coordinates of 1, 2 and

3 3 Methods and Materials. All the experiments were carried out under an inert atmosphere, using Schlenk techniques for the syntheses. Solvents were deoxygenated and dried according to standard procedures. [Fe(CO) 2 ( 2 -dppe)( 2 -pdt)] 1 and [Mo(CO) 3 (CH 3 CN) 3 ] 2 were prepared according to reported procedures. The NMR spectra ( 1 H, 31 P, 13 C) were recorded in CDCl 3 solution with a Bruker AMX 400, AC300 and DRX 500 spectrometers of the "Service de RMN de l'université de Bretagne Occidentale, Brest". 2D NMR experiments were carried out on a Bruker DRX 500 spectrometer. The infrared spectra were recorded on a Nicolet Nexus Fourier-transform spectrometer. Chemical analyses were made by the "Service de Microanalyse I.C.S.N.", Gif sur Yvette (France), or the "Centre de Microanalyse du CNRS", Vernaison (France). Crystal data for 1 were collected on a Oxford Diffraction X-Calibur-2 CCD diffractometer, equipped with a jet cooler device and graphite-monochromated Mo- K radiation ( = Å). The structure was solved and refined by standard procedures by the "Service de diffraction des RX de l'université de Bretagne Occidentale, Brest". 3 Mössbauer spectra were recorded at 4.2 K on a powder sample of 1, either on a low-field Mössbauer spectrometer equipped with a Janis SVT-400 cryostat or on a strong-field Mössbauer spectrometer equipped with an Oxford Instruments Spectromag 4000 cryostat containing an 8 T split-pair superconducting magnet. Both spectrometers were operated in a constant acceleration mode in transmission geometry. The isomer shifts were referenced against that of a room- temperature metallic iron foil. Analysis of the data was performed with the program WMOSS (WEB Research). Synthesis of [FeMo(CO) 5 ( 2 -dppe)(μ-pdt)] (1). Complexes [Fe(CO) 2 ( 2 -dppe)( 2 -pdt)] (1 g, mol) and [Mo(CO) 3 (CH 3 CN) 3 ] (0.59 g, mol) were stirred in THF (100 ml) at room temperature for 30 mn. The solution color turned readily to green. After evaporation of the solvent, the residue was chromatographed on a silica gel column and complex 1 was eluted with a hexane-dichloromethane (50:50) mixture. Evaporation of the volatiles and washing of the powder with pentane (3 x 10mL) afforded 1 as a green powder (0.65 mg, 50% Yield). Data for 1 are as follows: Anal. Calcd (%) for C 34 H 30 FeMoO 5 P 2 S 2 : C, 51.27; H, Found: C, ; H, IR (CH 2 Cl 2 ): (CO) 2016 (s), 1936 (s), 1882 (s), 1850 (m) cm P{ 1 H} NMR (CDCl 3 ): 60,8 (s). 1 H NMR (CDCl 3 ): (m, 20H, Ph), 3.11 (m, 2H, CH 2, dppe), 2.73 (m, 2H, CH 2, dppe), 2.68 (m, 2H + 1H, pdt), 2.56 (m, 2H, pdt), 1.84 (m, 1H, pdt). 13 C{ 1 H} (CDCl 3 ): (s, µ-co), (t, Fe(CO), 2 J PC = 16.5 Hz), (s, Mo(CO) eq ), (s, Mo(CO) ax ), (m, C ipso, Ph, 1 J PC = 44.0 Hz), (m, C ipso, Ph, 1 J PC = 31.5 Hz), (m, C meta, Ph), (s, C para, Ph), (s, C para, Ph), (pt, C ortho, Ph) ; (pt,

4 4 C ortho, Ph), 34.6 (s, pdt, CH 2 -CH 2 -CH 2 ), 25.2 (dd, dppe, CH 2 -CH 2, 1 J PC = 22.6 Hz, 2 J PC = 18.9 Hz), 23.3 (s, pdt, CH 2 -CH 2 -CH 2 ). [Fe(CO) 2 (dppe)(pdt)] + [Mo(CO) 3 (CH 3 CN) 3 ] THF/rt Ph Ph O C P P Fe S Ph Ph C O 1 S Mo CO CO CO DFT calculations. Geometry optimizations and energy calculations have been carried out in the DFT framework with the TURBOMOLE 6.4 suite of programs 4 by using the BP86 functional 5,6 in conjunction with the resolution-of-the-identity (RI) technique, 7 and a valence triple- basis set with polarization functions on all atoms (TZVP). 8 For the Mo atom a pseudopotential for the 28 inner electrons have been used. 9 Single point energy calculations have also been performed on the geometry optimized at the BP86/TZVP level of theory using the B3LYP hybrid functional 10,11 and the same basis set for electronic structure analysis. Mössbauer parameters (isomer shift ; quadrupole spitting E Q ; have been calculated using the ORCA suite of programs 12 at the B3LYP/TZVP level of theory on the geometries optimized using the BP86/TZVP scheme. For the evaluation of the isomer shift the electron densities at the Fe nuclei [ (0)] have been calculated. Indeed, the isomer shift is proportional to the electron density at the [ (0)] difference at the Fe nuclei between the studied and a reference system ( -Fe at 300 K), and can be described by the equation: = ([ (0)] A) + C where where A is a constant chosen close to the electron density at Fe nucleus in the reference state. and C can be obtained by a linear regression between the calculated [ (0)] and the experimental values of the isomer shift for a set of Fe-complexes. In this work we have used the equation with the regression coefficients = 0.298, A=11580 and C=1.118 obtained by the linear fitting of a set of Fe-complexes by Neese et al. 13 using the same computational scheme as that of these calculations. References (1) Takács, J.; Markó, L.; Párkányi, L. J. Organomet. Chem. 1989, 361, (2) Herrmann, W. A.; Salzer, A. Synthetic Methods of Organometallic and Inorganic Chemistry, Vol 1; Thieme, New York, 1996,

5 5 (3 ) Programs used: (a) SHELX 97 : Sheldrick, G. M. University of Göttingen, Germany, 1998; (b) WinGX -A Windows Program for Crystal Structure Analysis: Farrugia, L.J. J. Appl. Cryst. 1999, 32, (4) Ahlrichs, R.; Bar, M.; Haser, M.; Horn, H.; Kolmel, C. Chem. Phys. Lett. 1989, 162, (5) Becke, A. Phys. Rev. A 1988, 38, (6) Perdew, J. Phys. Rev. B 1986, 33, (7) Eichkorn, K.; Treutler, O.; Ohm, H.; Haser, M.; Ahlrichs, R. Chem. Phys. Lett. 1995, 240, (8) Schafer, A.; Huber, C.; Ahlrichs, R. J. Chem. Phys. 1994, 100, (9) Andrae, D.; Haeussermann, U.; Dolg, M.; Stoll, H.; Preuss, H. Theor. Chim. Acta 1990, 77, (10) Becke, A. D. J. Chem. Phys. 1993, 98, (11) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, (12) Neese, F. ORCA-an ab initio, density functional and semiempirical program package, version 3.0.1; Department of molecular theory and spectroscopy, Max Planck Institute for Chemical Energy Conversion, D Muelheim/Ruhr, Germany. (13) Römelt, M.; Ye, S.; Neese, F. Inorg.Chem. 48, 2009,

6 Figure S1. IR spectrum of 1 in CH 2 Cl 2 (carbonyl region) 6

7 Figure S2. 31 P{ 1 H} NMR spectrum of 1 in CDCl 3 (, ppm) 7

8 8 Et 2 O / / Et 2 O H 2 O / / / // // Figure S3: 1 H NMR spectrum of 1 in CDCl 3 (, ppm)

9 Figure S4: COSY 1 H- 1 H NMR spectrum of 1 in CDCl 3 9

10 Figure S5: 13 C{ 1 H} NMR spectrum (CO and C 6 H 5 region) of 1 in CDCl 3 (, ppm) 10

11 11 13 CO labeling studies were also performed by synthesizing [FeMo(CO) 5 ( 2 -dppe)(μ-pdt)] (1*) by reacting the 13 C-labeled precursor [Fe(CO) 2 ( 2 -dppe)( 2 -pdt)] with [Mo(CO) 3 (MeCN) 3 ]. 13 C{ 1 H} NMR spectrum of 1* in CDCl 3 suggested, as expected, an intramolecular transfer of CO from the iron framework to the molybdenum giving the observed {Mo(CO) 4 } moiety. Figure S6: 13 C{ 1 H} NMR spectrum (CO and C 6 H 5 region) of 13 C-labeled complex 1 in CDCl 3 (, ppm)

12 Figure S7. 31 P{ 1 H} NMR spectrum of 13 C-labeled complex 1 in CDCl 3 (, ppm) 12

13 Figure S8. IR spectra of 1 (red trace) and 13 C-labeled complex 1* (blue trace) in CH 2 Cl 2 (carbonyl region) 13

14 Figure S9. Calculated IR spectrum of 1 using the BP86/TZVP computational scheme (carbonyl region) 14

15 Figure S10. Charge partitioning scheme of 1 and 2 with in the upper part the NBO charges of each fragment. Charges are calculated using the BP86 functional, and in parenthesis, the B3LYP functional (see SI for details of calculations) 15

16 16 {Fe(dppe)(CO)(pdt)} {Mo(CO) 4} Figure S11. Orbital diagram and relevant frontier molecular orbitals of the [FeMo(CO) 5 ( 2 - dppe)(μ-pdt)] complex (1). The HOMO of the {Mo(CO) 4 } fragment interacts with the LUMO of the {Fe(dppe)(CO)(pdt)} fragment, to give a bonding orbital, which is the HOMO-2 in 1, and describes the Fe-Mo bond, and an antibonding orbital, which is the LUMO in 1. The bonding orbital is mainly localized on the {Mo(CO) 4 } fragment because of the large energy separation between HOMO and LUMO of the two fragments. HOMO-1 and HOMO-2 of the {Mo(CO) 4 } fragment becomes HOMO and HOMO-1 in 1 and remain almost completely localized on this part of the molecule.

17 Figure S12. Orbital diagram and relevant frontier molecular orbitals of the [Fe(CO) 2 (PMe 3 )(µpdt)fe(pme 3 )(CO) 2 ] complex (2). The HOMO of the {Fe d (CO) 2 (PMe 3 )} fragment interacts with the LUMO of the {Fe p (CO) 2 (PMe 3 )(pdtme 2 )} fragment, to give a bonding orbital, which is the HOMO in 2, and represents the Fe-Fe bond, and an antibonding orbital, which is the LUMO in 2. The bonding orbital is more delocalized on the entire complex with respect to 1 because of the small energy separation between HOMO and LUMO of the two fragments. 17

18 18 Figure S13. Schematic representation of the calculated structures of 2 and 2 + with selected geometrical parameters. Fe p Fe d Fe p Fe d

19 i / µa E / V Figure S14. Cyclic voltammetry of [FeMo(CO) 5 ( 2 -dppe)(μ-pdt)] (1, 1.03 mm) in CH 2 Cl 2 [NBu 4 ][PF 6 ] (inert atmosphere of N 2 or Ar, vitreous carbon electrode, v = 1 Vs -1, potential in V / Fc + /Fc).

20 20 i p / v 1/ v (V/s) ipa ox ipc red Figure S15 Scan rate dependence of the current functions for the oxidation ( ) and for the reduction ( ) of [FeMo(CO) 5 ( 2 -dppe)(μ-pdt)] (1, 1.34 mm) in CH 2 Cl 2 [NBu 4 ][PF 6 ] showing that the oxidation is a diffusion controlled, one-electron process while the reduction occurs according to an ECE-type mechanism at slow scan rates (v < 1 V s-1).

21 21 Table S1. Experimental and calc. Mössbauer parameters for 1 (mm/s) E Q (mm/s) fwhm (mm/s) exp calc Table S2. Calculated Mössbauer parameters of 2 and 2 +. Calculations have been carried out at the B3LYP/ TZVP level of theory on the geometries optimized with the BP86/TZVP scheme. (mm s -1 ) E Q (mm s -1 ) Fe p Fe d Fe p Fe d Fe p Fe d (exp) a 0.06, , (exp) a 0.09, , (exp) b 0.06, , , , , 1 0, (exp) b 0.105, , , 0.6 a) Taken from Ref. 14 of the main text; b) Taken from Ref. 16 of the main text

22 22 Table S3. Atomic contribution to the electron population of relevant MOs in 1 and 2 (in parenthesis is the population of d orbital for Fe and Mo). 1 HOMO HOMO-1 HOMO-2 Mo (1.119) (1.133) (0.841) {(CO) 4 } Mo Fe (0.084) (0.089) (0.228) {(CO)} Fe {(dppe)} Fe {pdt} HOMO HOMO-1 HOMO-2 Fe p (0.423) (0.189) (0.528) {(CO) 2 } Fep {(PMe 3 )} Fep Fe d (0.569) (0.367) (0.668) {(CO) 2 } Fed {(PMe 3 )} Fed {pdtme 2 }

23 23 Table S4. DFT calculated cartesian coordinates of 1, 2 and C O Fe C O S Mo C O S C C C C O C O H H H H H H P P C C C C C C C C C C C H H H H H C C C C C H H H H H H H H H C C C C C H H H H H C C C C C H H H H H C P Fe C O

24 24 C C S Fe C O S C C C C O P C C O C C H H H H H H H H H H H H H H H H H H H H H H C C H H H H H H C P C C Fe C O C O Fe P C S C C C S C O C O C C C H H H H C H H H H H H H H

25 H H H H H H H H H H H H H H H H