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Bessac F, Frenking G. Chemical Bonding in Phosphane and Amine Complexes of Main Group Elements and Transition Metals. Inorg Chem 2006; 45:6956-64. [PMID: 16903755 DOI: 10.1021/ic060541a] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The geometries and bond dissociation energies of the main group complexes X3B-NX3, X3B-PX3, X3Al-NX3, and X3Al-PX3 (X = H, Me, Cl) and the transition metal complexes (CO)5M-NX3 and (CO)5M-PX3 (M = Cr, Mo, W) have been calculated using gradient-corrected density functional theory at the BP86/TZ2P level. The nature of the donor-acceptor bonds was investigated with an energy decomposition analysis. It is found that the bond dissociation energy is not a good measure for the intrinsic strength of Lewis acidity and basicity because the preparation energies of the fragments may significantly change the trend of the bond strength. The interaction energies between the frozen fragments of the borane complexes are in most cases larger than the interaction energies of the alane complexes. The bond dissociation energy of the alane complexes is sometimes higher than that of the borane analogues because the energy for distorting the planar equilibrium geometry of BX3 to the pyramidal from in the complexes is higher than for AlX3. Inspection of the three energy terms, DeltaE(Pauli), DeltaE(orb), and DeltaE(elstat), shows that all three of them must be considered to understand the trends of the Lewis acid and base strength. The orbital term of the donor-acceptor bonds with the Lewis bases NCl3 and PCl3 have a higher pi character than the bonds of EH3 and EMe3, but NCl3 and PCl3 are weaker Lewis bases because the lone-pair orbital at the donor atoms N and P has a high percent s character. The calculated DeltaE(int) values suggest that the trends of the intrinsic Lewis bases' strengths in the main-group complexes with BX3 and AlX3 are NMe3 > NH3 > NCl3 and PMe3 > PH3 > PCl3. The transition metal complexes exhibit a somewhat different order with NH3 > NMe3 > NCl3 and PMe3 > PH3 > PCl3. The slightly weaker bonding of NMe3 than that of NH3 comes from stronger Pauli repulsion. The bond length does not always correlate with the bond dissociation energy, nor does it always correlate with the intrinsic interaction energy.
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Affiliation(s)
- Fabienne Bessac
- Université Paul Sabatier, Laboratoire de Physique Quantique, 118 Route de Narbonne, F-31062 Toulouse, France
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Záliš S, Vlček A, Daniel C. The Character of Low-Lying Excited States of Mixed-Ligand Metal Carbonyls. TD-DFT and CASSCF/CASPT2 Study of [W(CO)4L] (L = ethylenediamine, N,N'-dialkyl-1,4-diazabutadiene) and [W(CO)5L] (L = pyridine, 4-cyanopyridine). ACTA ACUST UNITED AC 2003. [DOI: 10.1135/cccc20030089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This contribution presents the results of the TD-DFT and CASSCF/CASPT2 calculations on [W(CO)4(MeDAB)] (MeDAB = N,N'-dimethyl-1,4-diazabutadiene), [W(CO)4(en)] (en = ethylenediamine), [W(CO)5(py)] (py = pyridine) and [W(CO)5(CNpy)] (CNpy = 4-cyanopyridine) complexes. Contrary to the textbook interpretation, calculations on the model complex [W(CO)4(MeDAB)] and [W(CO)5(CNpy)] show that the lowest W→MeDAB and W→CNpy MLCT excited states are immediately followed in energy by several W→CO MLCT states, instead of ligand-field (LF) states. The lowest-lying excited states of [W(CO)4(en)] system were characterized as W(COeq)2→COax CT excitations, which involve a remarkable electron density redistribution between axial and equatorial CO ligands. [W(CO)5(py)] possesses closely-lying W→CO and W→py MLCT excited states. The calculated energies of these states are sensitive to the computational methodology used and can be easily influenced by a substitution effect. The calculated shifts of [W(CO)4(en)] stretching CO frequencies due to excitation are in agreement with picosecond time-resolved infrared spectroscopy experiments and confirm the occurrence of low-lying M→CO MLCT transitions. No LF electronic transitions were found for either of the complexes studied in the region up to 4 eV.
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Li S, Hall MB. Modeling the active sites of metalloenzymes. 4. Predictions of the unready states of [NiFe] Desulfovibrio gigas hydrogenase from density functional theory. Inorg Chem 2001; 40:18-24. [PMID: 11195380 DOI: 10.1021/ic0001715] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Density functional theory has been used to predict the structures of a variety of active site models for the unready states, Ni-A and Ni-SU, of the [NiFe] hydrogenase from Desulfovibrio gigas. By comparing available experimental results on Ni-A, Ni-SU, and Ni-SI with the computational results on these model complexes, we have been able to identify the most likely formulas and structures for the active sites of Ni-A and Ni-SU. Ni-A is predicted to be a Ni(III)-Fe(II) species with the bridging hydroxo ligand, rather than the expected oxo ligand, while Ni-SU is predicted to be a Ni(II)-Fe(II) species with a water molecule coordinated to the Fe center. Both have one of the terminal S atoms (cysteines) protonated.
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Affiliation(s)
- S Li
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
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Zarić SD. Theoretical study of cation–π interactions of the metal complex cation, [Co(NH3)6]3+, with ethylene and acetylene. Chem Phys 2000. [DOI: 10.1016/s0301-0104(00)00074-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Snee PT, Yang H, Kotz KT, Payne CK, Harris CB. Ultrafast Infrared Studies of the Reaction Mechanism of Silicon−Hydrogen Bond Activation by η5-CpV(CO)4. J Phys Chem A 1999. [DOI: 10.1021/jp991964j] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Preston T. Snee
- Department of Chemistry, University of California, Berkeley, California, 94720 and Chemical Sciences Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California, 94720
| | - Haw Yang
- Department of Chemistry, University of California, Berkeley, California, 94720 and Chemical Sciences Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California, 94720
| | - Kenneth T. Kotz
- Department of Chemistry, University of California, Berkeley, California, 94720 and Chemical Sciences Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California, 94720
| | - Christine K. Payne
- Department of Chemistry, University of California, Berkeley, California, 94720 and Chemical Sciences Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California, 94720
| | - Charles B. Harris
- Department of Chemistry, University of California, Berkeley, California, 94720 and Chemical Sciences Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California, 94720
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Yang H, Asplund MC, Kotz KT, Wilkens MJ, Frei H, Harris CB. Reaction Mechanism of Silicon−Hydrogen Bond Activation Studied Using Femtosecond to Nanosecond IR Spectroscopy and Ab Initio Methods. J Am Chem Soc 1998. [DOI: 10.1021/ja980692f] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- H. Yang
- Contribution from the Department of Chemistry, University of California, Berkeley, California 94720, Chemical Sciences Division and Physical Biosciences Division, MS Calvin Laboratory, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - M. C. Asplund
- Contribution from the Department of Chemistry, University of California, Berkeley, California 94720, Chemical Sciences Division and Physical Biosciences Division, MS Calvin Laboratory, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - K. T. Kotz
- Contribution from the Department of Chemistry, University of California, Berkeley, California 94720, Chemical Sciences Division and Physical Biosciences Division, MS Calvin Laboratory, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - M. J. Wilkens
- Contribution from the Department of Chemistry, University of California, Berkeley, California 94720, Chemical Sciences Division and Physical Biosciences Division, MS Calvin Laboratory, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - H. Frei
- Contribution from the Department of Chemistry, University of California, Berkeley, California 94720, Chemical Sciences Division and Physical Biosciences Division, MS Calvin Laboratory, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - C. B. Harris
- Contribution from the Department of Chemistry, University of California, Berkeley, California 94720, Chemical Sciences Division and Physical Biosciences Division, MS Calvin Laboratory, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720
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