Relativistic effects in metallocorroles: Comparison of molybdenum and … · 2017-05-08 · S1!...
Transcript of Relativistic effects in metallocorroles: Comparison of molybdenum and … · 2017-05-08 · S1!...
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Supporting Information
Relativistic effects in metallocorroles:
Comparison of molybdenum and tungsten biscorroles
Abraham B. Alemayehu,a Hugo Vazquez-Lima,a Laura J. McCormickb and Abhik Ghosh*,a
a Department of Chemistry and Center for Theoretical and Computational Chemistry, UiT
– The Arctic University of Norway, 9037 Tromsø, Norway; E-mail: [email protected]. b Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-
8229.
Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2017
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A. Experimental section
Materials. Free-base meso-triarylcorroles were synthesized according to a literature
procedure.1 Anhydrous decahydronaphthalene (decalin), molybdenum hexacarbonyl
99.99%) and potassium carbonate (granulated) were purchased from Sigma-Aldrich and
used as received. Silica gel 60 (0.04-0.063 mm particle size, 230-400 mesh, Merck) was
employed for flash chromatography. Silica gel 60 preparative thin-layer chromatographic
plates (20 cm x 20 cm x 0.5 mm, Merck) were used for final purification of all complexes.
Instrumental methods. UV-visible spectra were recorded on an HP 8453
spectrophotometer. 1H NMR spectra were recorded on a 400 MHz Bruker Avance III HD
spectrometer equipped with a 5 mm SmartProbe at room temperature in CDCl3 and
referenced to residual CHCl3 7.26 ppm. However, as in the case of the W[TpXPC]2
reported earlier,2 the 1H NMR spectra (including variable temperature experiments) of
Mo[TpXPC]2 exhibited strongly overlapping peaks in the aromatic region, which proved
unenlightening, except for confirming the diamagnetism of the complexes. Electrospray
ionization mass spectra were recorded on an LTQ Orbitrap XL spectrometer.
Cyclic voltammetry was carried out at 298 K with an EG&G Model 263A
potentiostat with a three-electrode system comprising a glassy carbon working electrode, a
platinum wire counterelectrode, and a saturated calomel reference electrode (SCE). Tetra(n-
butyl)ammonium perchlorate, recrystallized twice from absolute ethanol and dried in a
desiccator for at least 2 weeks, was used as the supporting electrolyte. Anhydrous CH2Cl2
(Aldrich) was used as solvent. The reference electrode was separated from the bulk solution
by a fritted-glass bridge filled with the solvent/supporting electrolyte mixture. The
electrolyte solution was purged with argon for at least 2 min and all measurements were
carried out under an argon blanket. All potentials were referenced to the SCE.
General procedure for the synthesis of Mo[TpXPC]2. To a 20-mL microwave vial
was added free-base corrole H3[TpXPC] (0.170 mmol), Mo(CO)6 (0.527 mmol), K2CO3
1 B. Koszarna and D. T. Gryko, J. Org. Chem. 2006, 71, 3707-3717. 2 A. B. Alemayehu, H. Vazquez-Lima, K. J. Gagnon, and A. Ghosh, Chem. Eur. J. 2016, 22, 6914-6920.
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(100 mg), decalin (10 mL), and a stir bar. The vial was sealed and flushed with a stream of
argon for 10 min. and then heated to 186 °C (in an oil bath) and maintained at that
temperature for 16 h with constant stirring under Ar. Completion of the reaction was
indicated by the disappearance of the Soret absorption of the free-base corrole and the
appearance of a new Soret maximum at approximately 355 nm. Upon cooling, the reaction
mixture was loaded on to a silica gel column and eluted with n-hexane, which resulted in
the removal of the decalin. Changing the solvent to 3:2 n-hexane/dichloromethane then
resulted in a red band consisting of the MoVO corrole. The Mo biscorrole finally eluted
with 98:2 dichloromethane/ethyl acetate as a yellowish brown band. All fractions with λmax
∼355 nm were combined and evaporated to dryness. The residue was further purified by
preparative thin-layer chromatography on a silica gel 60 plate with 95:5
dichloromethane/ethyl acetate to afford the analytically pure product (as evidenced by TLC
and exceptionally clean mass spectra). Yields and analytical details for the different
complexes are as follows.
Mo[TPC]2. Yield 24.6 mg (25.3%). UV-vis (CH2Cl2) λmax [nm, ε x 10-4 (M-1cm-1)]:
356 (6.15), 421 (4.71), 798 (0.30), 908 (0.0.48). 1H NMR (400 MHz, CD2Cl2, 253K): δ
8.52-6.41 (overlapping multiplets, unassignable). MS (ESI): M+ = 1144.2926 (expt),
1144.2914 (calcd for C74H46N8Mo). Elemental analysis: Found C 58.40, H 2.31, N 6.40;
calcd C 58.82, H 2.62, N 6.77.
Mo[TpMePC]2. Yield 28.8 mg (27.6 %). UV-vis (CH2Cl2): λmax (nm), [ε x 10-4 (M-
1cm-1)]: 362 (7.84), 428 (3.67), 808 (0.54), 909 (1.03). 1H NMR (400 MHz, CD2Cl2, 253K):
δ 8.52-6.39 (overlapping multiplets, 40 H), 2.47 (s, 6H, p-CH3), 2.42(s, 6H, p-CH3), 2.28
(s, 6H, p-CH3). MS (ESI): M+ = 1228.3865 (expt), 1228.3855 (calcd for C80H58N8Mo).
Elemental analysis: Found C 72.65, H 3.31, N 8.62; calcd: C 72.29, H 3.96, N 8.99.
Mo[TpOMePC]2. Yield 34.3 mg (30.5 %) UV-vis (CH2Cl2): λmax (nm), [ε x 10-4 (M-
1cm-1)]: 350 (7.24), 425 (3.76), 811 (0.96), 909 (0.89). 1H NMR (400 MHz, CD2Cl2,
253K): δ 8.28-6.00 (overlapping multiplets, 40 H), 3.93 (s, 6H, p-OCH3), 3.90 (s, 6H, p-
OCH3), 3.82 (s, 6H, p-OCH3). MS (ESI): M+ = 1324.3563 (expt), 1323.3551 (calcd for
C80H58O6N8Mo). Elemental analysis: Found C 72.31, H 4.75, N 8.00; calcd C 72.61, H
4.42, N 8.47. MS (ESI): M+ = 1324.35 (expt), 1323.31 (calcd for C80H58O6N8Mo).
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X-ray structure determination of Mo[TpMePC]2·CH2Cl2. X-ray quality crystals
of Mo[TpMePC]2·CH2Cl2 were obtained by diffusion of methanol vapor into a
concentrated solution of Mo[TpMePC]2 in dichloromethane. X-ray data were collected on
beamline 11.3.1 at the Advanced Light Source with a Bruker D8 diffractometer equipped
with a PHOTON100 CMOS detector operating in shutterless mode. A brown rod-shaped
crystal coated in protective oil was mounted on a MiTeGen kapton micromount and cooled
to 100(2) K under a nitrogen stream using an Oxford Cryostream 800 Plus. Diffraction data
were collected using synchrotron radiation monochromated using a silicon (111) crystal to
λ = 0.8857(1) Å. The structure was solved by intrinsic phasing using SHELTX3 and refined
on F2 using SHELXL-2014.4 All non-hydrogen atoms were refined anisotropically.
Hydrogen atoms were included at their geometrically estimated positions. Partial
occupancy carbon and chlorine atoms of the disordered CH2Cl2 molecule were constrained
to have equal Uij values.
3 G. M. Sheldrick, Acta Cryst. A 2015, 71, 3-8. 4 G. M. Sheldrick, Acta Cryst. C, Struct. Chem. 2015, 71, 3-8.
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B. Computational section
Methods. All calculations were carried with the ADF 20165 program system using
the B3LYP functional, ZORA STO-TZP6 basis sets, and appropriately fine integration
grids and tight SCF and geometry optimization criteria. TDDFT calculations employed the
CAMY-B3LYP7 functional. Scalar and spin-orbit relativistic effects were taken into
account with the ZORA Hamiltonian8,9,10 and Grimme’s D311 dispersion correction was
used throughout. Solvent conditions (dichlormethane) were simulated with the COSMO
model.12 For the determination of relativistic effects, TDDFT calculations were also carried
out with a nonrelativistic Hamiltonian; the basis sets employed in these calculations,
however, were still those optimized for relativistic ZORA calculations.
Although the present calculations focused on the near-IR spectral features of the
compounds studied, it is worth noting that limitations of computational resources (in terms
of the number of transitions that could be calculated) led to certain challenges in the
TDDFT simulation of the Soret manifolds of Mo and W bis-TPC complexes. Scalar
relativistic calculations on these complexes could only provide a satisfactory simulation of
spectral features down to 370 nm. Scalar relativistic calculations on unsubstituted Mo and
W biscorrole on the other hand could reach down to 300 nm, whereas spin-orbit
calculations could only reach down to 405 nm.
5 G. te Velde, F. M. Bickelhaupt, E. J. Baerends, C. Fonseca Guerra, S. J. A. van Gisbergen, J. G. Snijders and T. Ziegler, J. Comput. Chem. 2001, 22, 931-967. 6 E. van Lenthe, R. van Leeuwen, E. J. Baerends and J. G. Snijders, Int. J. Quantum Chem. 1996, 57, 281-293. 7 M. Seth, T. Ziegler, J. Chem. Theory Comput. 2012, 8, 901-907. 8 E. v. Lenthe, E. J. Baerends and J. G. Snijders, J. Chem. Phys., 1993, 99, 4597-4610. 9 E. v. Lenthe, E. J. Baerends and J. G. Snijders, J. Chem. Phys. 1994, 101, 9783-9792. 10 E. van Lenthe, A. Ehlers and E.-J. Baerends, J. Chem. Phys. 1999, 110, 8943-8953. 11 S. Grimme, J. Antony, S. Ehrlich and H. Krieg, J. Chem. Phys. 2010, 132, 154104. 12 C. C. Pye and T. Ziegler, Theor. Chem. Acc. 1999, 101, 396-408.
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Selected computational results. (a) Comparison of experimental and TDDFT spectra.
Figure S1. Comparison of experimental (blue) and scalar-relativistic TDDFT (black) UV-vis spectra for Mo[TPC]2.
Figure S2. Comparison of experimental (orange) and scalar-relativistic TDDFT (black) UV-vis spectra for W[TPC]2.
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(b) Comparison of ZORA scalar and two-component spin-orbit relativistic TDDFT spectra. Both levels of theory led to very similar calculated spectra in the region above 405 nm, i.e., the region where both types of calculations were feasible.
Figure S3. Comparison of ZORA scalar (red) and spin-orbit relativistic TDDFT spectra for M[C]2, where M = Mo (top) and W (bottom) and C = unsubstituted corrole.
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(c) Details of TDDFT transitions, MOs and spin densities.
Figure S4. CAMYB3LYP/STO-TZP frontier MOs of Mo[TPC]2, along with their Kohn-Sham orbital energies and % d character.
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Figure S5. Scalar-relativistic CAMYB3LYP/STO-TZP/COSMO MO energy level diagrams for W[TPC]2 (C2), Mo[TPC]2 (C2) and Mo[C]2 (C2). Unoccupied and doubly occupied MOs are shown in red and black, respectively, and MOs with >25% metal d character are indicated by the label d. The energy range marked G is that spanned by the Goutermann-type frontier MOs.
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Figure S6. Spin density plots for the cationic and anionic states of Mo[TPC]2. Majority and minority spin densities are shown in cyan and burgundy, respectively. The contour has been set at 0.009 e·Å−3.
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Table 1. Main transitions for Mo[TPC]2 obtained from a scalar-relativistic CAMY-B3LYP/TZP/COSMO TDDFT calculation.
E (eV) Symmetry f λ (nm) From To %
1.264 B 0.2437 981 HOMO – 1 LUMO 97.6
2.836 B 0.5861 437 HOMO LUMO + 5 72.1
HOMO – 1 LUMO + 2 8.8
HOMO – 1 LUMO + 4 5.3
HOMO – 3 LUMO + 1 2.8
HOMO – 4 LUMO 2.6
2.906 A 0.5558 427 HOMO LUMO + 6 76.3
HOMO – 5 LUMO 9.6
HOMO – 1 LUMO + 1 4.4
2.985 A 0.2938 415 HOMO – 5 LUMO 63.8
HOMO LUMO + 6 10.0
HOMO – 8 LUMO 8.0
HOMO – 7 LUMO 4.7
HOMO – 16 LUMO 2.2
HOMO – 1 LUMO + 6 2.1
3.171 B 0.7274 391 HOMO – 6 LUMO 22.8
HOMO – 4 LUMO 19.5
HOMO – 2 LUMO + 1 13.9
HOMO – 1 LUMO + 5 9.1
HOMO – 10 LUMO 7.2
HOMO – 2 LUMO + 3 6.9
HOMO – 9 LUMO 3.4
HOMO – 1 LUMO + 4 2.9
HOMO – 11 LUMO 2.4
HOMO LUMO + 7 2.0
3.336 A 0.8921 372 HOMO – 7 LUMO 21.3
HOMO – 2 LUMO + 2 20.1
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HOMO – 2 LUMO + 4 10.9
HOMO – 5 LUMO 9.0
HOMO – 3 LUMO + 2 6.0
HOMO – 1 LUMO + 6 5.2
HOMO – 22 LUMO 4.3
HOMO – 3 LUMO + 4 3.6
HOMO – 8 LUMO 3.6
HOMO LUMO + 8 3.0
HOMO – 3 LUMO + 5 2.9
3.363 B 0.2277 369 HOMO – 10 LUMO 52.8
HOMO – 11 LUMO 17.3
HOMO – 20 LUMO 7.8
HOMO – 13 LUMO 3.4
HOMO – 4 LUMO 3.1
HOMO – 6 LUMO 3.1
HOMO – 17 LUMO 2.8