Electronic structure of high-spin iron(IV) complexes

European Journal of Inorganic Chemistry

Volumn , Issue 23, 2004, Pages 4555-4560

  Ghosh, Abhik ^a   Tangen, Espen ^a   Ryeng, Hege ^a   Taylor, Peter R ^b  

^a UNIVERSITY OF TROMSØ   (Norway)

^b UNIVERSITY OF WARWICK   (United Kingdom)

Author keywords

Diamond core; High spin species; Iron; Nonheme; Oxo ligand; Quantum chemistry

Indexed keywords

CHLORINE COMPOUNDS; DENSITY FUNCTIONAL THEORY; ELECTRONIC STRUCTURE; ENZYMES; GROUND STATE; IRON COMPOUNDS; LIGANDS; SPIN DYNAMICS;

DIAMOND CORE; ELECTRONIC.STRUCTURE; ENERGY; HIGH SPINS; HIGH-SPIN SPECIES; NON-HEME IRON ENZYMES; NONHEME; OXO LIGANDS; SPIN SPECIES; SPIN STATE;

QUANTUM CHEMISTRY;

CATION; CHLORIDE; COLLINS SOLUTION; DIAMOND; ENZYME; HEME; IRON COMPLEX;

AB INITIO CALCULATION; ARTICLE; COMPLEX FORMATION; DENSITY FUNCTIONAL THEORY; ELECTRON; ENERGY; QUANTUM CHEMISTRY; STEREOSPECIFICITY; SYNTHESIS;

EID: 11144334240     PISSN: 14341948     EISSN: None     Source Type: Journal    
DOI: 10.1002/ejic.200400362     Document Type: Article

References (33)

1. For a recent review, see: M. Costas, M. P. Mehn, M. P. Jensen, L. Que, Jr., Chem. Rev. 2004, 104, 939-986.
2. For a recent review, see: E. Y. Tshuva, S. J. Lippard, Chem. Rev. 2004, 104, 987-1011.
3. K. L. Kostka, B. G. Fox, M. P. Hendrich, T. J. Collins, C. E. F. Rickard, L. J. Wright, E. Münck, J. Am. Chem. Soc. 1993, 115, 6746-6757.
4. L. Shu, J. C. Nesheim, K. Kauffmann, E. Münck, J. D. Lipscomb, L. Que, Jr., Science 1997, 275, 515-518.
5. P. J. Riggs-Gelasco, L. Shu, S. Chen, D. Burdi, B. H. Huynh, L. Que, Jr., J. Stubbe, J. Am. Chem. Soc. 1998, 120, 849-860.
6. Y. Dong, L. Que, Jr., K. Kauffmann, E. Münck, J. Am. Chem. Soc. 1995, 117, 11377-11378.
7. H. Zheng, S. J. Yoo, E. Münck, L. Que, Jr., J. Am. Chem. Soc. 2000, 122, 3789-3790.
8. J. C. Price, E. W. Barr, B. Tirupati, J. M. Bollinger, Jr., C. Krebs, Biochemistry 2003, 42, 7497. Addition/Correction: Biochemistry 2004, 43, 1134-1134.
9. J. C. Price, E. W. Barr, B. Tirupati, J. M. Bollinger, Jr., C. Krebs, Biochemistry 2003, 42, 7497. Addition/Correction: Biochemistry 2004, 43, 1134-1134.
10. For a review, see: A. Ghosh, E. Steene, J. Biol. Inorg. Chem. 2001, 6, 739-752.
11. For a critical review of high-level ab initio calculations on systems of bioinorganic interest, see: A. Ghosh, P. R. Taylor, Curr. Opin. Chem. Biol. 2003, 7, 113-124.
12. III derivatives: A. Ghosh, B. J. Persson, P. R. Taylor, J. Biol. Inorg. Chem. 2003, 8, 507-511.
13. The PW91 calculations were carried out using the ADF program system, using Slater-type TZP basis sets and a fine mesh for numerical integration of matrix elements. The B3LYP calculations were carried out using the program Turbomole and Gaussian basis sets of TZP quality. Adequately tight converegence criteria for geometry optimizations were used in all the calculations.
14. 2 symmetry ligand orbital is a combination of the N lone-pairs. The CASPT2 calculations were performed using the program Molcas 5.2 and the CCSD(T) calculations with Molpro 2002.
15. BSI consisted of Dunning's cc-pVDZ basis sets on C, N O, and H, the aug-cc-pVDZ basis on Cl (T. H. Dunning, J. Chem. Phys. 1989, 90, 1007-1023), and a [6s5p4d3f2g] atomic natural orbital (ANO) basis on Fe (B. J. Persson, P. R. Taylor, unpublished results). BS2 consisted of Dunning's cc-pVTZ basis sets on C, N O, and H, the aug-cc-pVTZ basis on Cl (T. H. Dunning, J. Chem. Phys. 1989, 90, 1007-1023), and a [7s6p5d4f3g] ANO basis on Fe (B. J. Persson, P. R. Taylor, unpublished results). The Fe ANO basis sets are optimized for calculations that include Fe 3s3p correlation, the effects of which are not negligible here.
16. BSI consisted of Dunning's cc-pVDZ basis sets on C, N O, and H, the aug-cc-pVDZ basis on Cl (T. H. Dunning, J. Chem. Phys. 1989, 90, 1007-1023), and a [6s5p4d3f2g] atomic natural orbital (ANO) basis on Fe (B. J. Persson, P. R. Taylor, unpublished results). BS2 consisted of Dunning's cc-pVTZ basis sets on C, N O, and H, the aug-cc-pVTZ basis on Cl (T. H. Dunning, J. Chem. Phys. 1989, 90, 1007-1023), and a [7s6p5d4f3g] ANO basis on Fe (B. J. Persson, P. R. Taylor, unpublished results). The Fe ANO basis sets are optimized for calculations that include Fe 3s3p correlation, the effects of which are not negligible here.
17. BSI consisted of Dunning's cc-pVDZ basis sets on C, N O, and H, the aug-cc-pVDZ basis on Cl (T. H. Dunning, J. Chem. Phys. 1989, 90, 1007-1023), and a [6s5p4d3f2g] atomic natural orbital (ANO) basis on Fe (B. J. Persson, P. R. Taylor, unpublished results). BS2 consisted of Dunning's cc-pVTZ basis sets on C, N O, and H, the aug-cc-pVTZ basis on Cl (T. H. Dunning, J. Chem. Phys. 1989, 90, 1007-1023), and a [7s6p5d4f3g] ANO basis on Fe (B. J. Persson, P. R. Taylor, unpublished results). The Fe ANO basis sets are optimized for calculations that include Fe 3s3p correlation, the effects of which are not negligible here.
18. BSI consisted of Dunning's cc-pVDZ basis sets on C, N O, and H, the aug-cc-pVDZ basis on Cl (T. H. Dunning, J. Chem. Phys. 1989, 90, 1007-1023), and a [6s5p4d3f2g] atomic natural orbital (ANO) basis on Fe (B. J. Persson, P. R. Taylor, unpublished results). BS2 consisted of Dunning's cc-pVTZ basis sets on C, N O, and H, the aug-cc-pVTZ basis on Cl (T. H. Dunning, J. Chem. Phys. 1989, 90, 1007-1023), and a [7s6p5d4f3g] ANO basis on Fe (B. J. Persson, P. R. Taylor, unpublished results). The Fe ANO basis sets are optimized for calculations that include Fe 3s3p correlation, the effects of which are not negligible here.
19. At present, there is extensive evidence (see, for example: P. E. M. Siegbahn, M. R. A. Blomberg, Chem. Rev. 2000, 100, 421-437) that DFT provides generally good results for geometries, spin density profiles, and a variety of other molecular properties for transition metal complexes. We believe that this generalization also holds for the species studied here and therefore largely refrain from commenting on the data presented in Table 1. However, one point worth noting is the relatively small amounts of spin density on the equatorial ligand set. By this criterion, the ligands may be described as relatively innocent, even though they must be extremely σ-donating.
20. For a discussion of population analyses, see: C. J. Cramer; Essentials of Computational Chemistry: Theories and Models, Wiley, Hoboken, NJ, USA, 2002, pp. 278-291.
21. A few more technical comments may be worthwhile. Examining the CASSCF and CASPT2 results suggests that the wave-functions for both states are somewhat multiconfigurational in character, but not exceptionally so. In this situation we would typically expect much closer agreement between CASPT2 and CCSD(T). We know that DFT (certainly with the functionals used here) tends to favour low-spin states; CASPT2 in its simplest implementation also tends to favour low-spin states but here we have used a modified Hamiltonian which gives a much better balanced treatment of different spin states, with no obvious preference for high or low spin. The 8-in-8 CASSCF/BS1 calculation itself gives 0.69 eV for the splitting (quintet lower), whereas a Hartree-Fock calculation gives 2.16eV, again with the quintet lower. From the Hartree-Fock value we infer that electron correlation makes a substantial contribution to the splitting, which is expected; from the CASSCF value we can infer further that much of this correlation contribution is non-dynamical correlation. We must also recognize that the basis sets used here for the CCSD(T) calculations, though large, are far from complete and the contribution of dynamical correlation may well be larger in a more complete basis set.
22. C. A. Grapperhaus, B. Mienert, E. Bill, T. Weyhermüller, K. Wieghardt, Inorg. Chem. 2000, 39, 5306-5317.
23. M. H. Lim, J.-W. Rohde, A. Stubna, M. R. Bukowski, M. Costas, R. Y. N. Ho, E. Münck, W. Nam, L. Que, Jr., Proc. Natl. Acad. Sci. U. S. A. 2003, 100, 3665-3670.
24. J. Kaizer, E. J. Klinker, N. Y. Oh, J.-U. Rohde, W. J. Song, A. Stubna, J. Kim, E. Munck, W. Nam, L. Que, Jr., J. Am. Chem. Soc. 2004, 126, 472-473.
25. J.-W. Rohde, J.-H. In, M. H. Lim, W. W. Brennessel, M. R. Bukowski, A. Stubna, E. Münck, W. Nam, L. Que, Jr., Science 2003, 299, 1037-1039.
26. H. Zheng, S. J. Yoo, E. Münck, L. Que, Jr., J. Am. Chem. Soc. 2000, 122, 3789-3790.
27. Y. Zang, Y. Dong, L. Que, Jr., K. Kauffmann, E. Münck, J. Am. Chem. Soc. 1995, 117, 1169-1170.
28. Y. Zang, J. Kim, Y. Dong, E. C. Wilkinson, E. H. Appelman, L. Que, Jr., J. Am. Chem. Soc. 1997, 119, 4197-4205.
29. 2v symmetry for species 2-4.
30. IVO: A. Ghosh, J. Almlöf, L. Que, Jr., J. Phys. Chem. 1994, 98, 5576-5579. The same effect (i. e. the complete localization of the spin density on the Fe and O atoms) was also noted in the first studies of high-valent iron diamond core intermediates A. Ghosh, J. Almlöf, L. Que, Jr., Angew. Chem. Int. Ed. Engl. 1996, 35, 770-772.
31. IVO: A. Ghosh, J. Almlöf, L. Que, Jr., J. Phys. Chem. 1994, 98, 5576-5579. The same effect (i. e. the complete localization of the spin density on the Fe and O atoms) was also noted in the first studies of high-valent iron diamond core intermediates A. Ghosh, J. Almlöf, L. Que, Jr., Angew. Chem. Int. Ed. Engl. 1996, 35, 770-772.
32. H. Kuramochi, L. Noodleman, D. A. Case, J. Am. Chem. Soc. 1997, 119, 11442-11451.
33. 3+,4+ diamond-core species, see: A. Ghosh, E. Tangen, E. Gonzalez, L. Que, Jr., Angew. Chem. Int. Ed. 2004, 43, 834-838.