Density Functional and Ab Initio Study of Cr(CO)n (n = 1−6) Complexes

Kim, Joonghan; Kim, Tae Kyu; Kim, Jangbae; Lee, Yoon Sup; Ihee, Hyotcherl

doi:10.1021/jp066081o

Cited by 22 publications

(42 citation statements)

References 104 publications

(222 reference statements)

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“…The (trigonal bipyramidal) T 0 minimum of Cr(CO) 5 is found to be higher than the (square pyramidal) S 0 minimum by 0.455 eV, similarly as in recent calculations. 27 The values for the CO stretch wavenumbers are well consistent with other calculations of these vibrations. 27,28 For a quality check of the lower frequencies, we applied the calculation also to the parent compound Cr(CO) 6 and found that they agree with the experimental ones 29 within o10% (most of them within o5%).…”

Section: Calculation Of the M(co) 5 Vibrationssupporting

confidence: 88%

Photodissociation of group-6 hexacarbonyls: observation of coherent oscillations in an antisymmetric (pseudorotation) vibration in Mo(CO)5 and W(CO)5

Kosma

Trushin

Fuß

et al. 2010

Phys. Chem. Chem. Phys.

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On dissociation of M(CO)(6), M = Cr, Mo and W, by a femtosecond UV laser (<270 to 360 nm), pronounced coherent oscillations are observed in the pentacarbonyl products on probing by long-wavelength (810 nm) ionization in the gas phase. They are vibrations in the ground state, driven by the slope from a conical intersection on relaxation from the initially formed excited state (S(1)). Surprisingly, with M = Mo and W we also find a fundamental of an antisymmetric (b(2) in C(4v)) vibration. From positive and negative displacements along such a coordinate one would expect the same signal, so that there should be only overtones. Vibrational selection rules are therefore considered for time-resolved spectroscopy. The reason for the symmetry breaking is suggested to result from the fact that the phase in superposition of wave functions is established by the pump process and this phase is conserved in probing, independently of the probe delay. An antisymmetric fundamental can be observed, if there is a small tunneling splitting in a state involved in the probe process. The observations also imply some conclusions on the dissociation and relaxation processes and the potentials: with longer wavelengths, the wave packet enters on the same surface but from a different direction to S(1). Only a very minor fraction of the available energy appears as coherent oscillation. There is no equipartition at the end, and a second CO is cleaved off in few picoseconds, even if there is only very little excess energy. Triplets do not contribute, even in the tungsten system and at longest wavelengths. The dissociation mechanism involves passage of the wave packet from all initial states over an avoided crossing to a repulsive ligand-field surface. It predicts that in some other molecules, the barrier caused thereby is larger and for long photolysis wavelength the lifetime is long enough for intersystem crossing to take place; it also predicts wavelength dependences in these cases. It is again emphasized that there is no vertical internal conversion; instead, the molecule is controlled by slopes and intersections of potentials. Also lifetimes can be considered as a control parameter in photochemistry.

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Section: Calculation Of the M(co) 5 Vibrationssupporting

confidence: 88%

Photodissociation of group-6 hexacarbonyls: observation of coherent oscillations in an antisymmetric (pseudorotation) vibration in Mo(CO)5 and W(CO)5

Kosma

Trushin

Fuß

et al. 2010

Phys. Chem. Chem. Phys.

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“…(Table 2 and Table S14–S16 of Supporting Information). As seen from Figure 1, the structure of Sc(CO) 5 differs sharply from Ti(CO) 5 22 and Cr(CO) 5 ,13, 21, 31 both of which have a C 4v structure with four CO groups being approximately coplanar. The Sc(CO) 6 molecule has a 2 B 1 ground state with C 2v symmetry.…”

Section: Resultsmentioning

confidence: 96%

“…Yet, the more symmetric structure, that is, octahedral quartet isomer O h ( 4 A 1g ), lies 24.3 kcal/mol higher in energy. By contrast, Ti(CO) 6 , 5 V(CO) 6, 32 and Cr(CO) 6 12, 21, 31 either have a slightly distorted or perfect octahedral structures.…”

Section: Resultsmentioning

confidence: 97%

B cell depletion with rituximab in patients with diffuse cutaneous systemic sclerosis

Lafyatis

Kissin

York

et al. 2009

Arthritis & Rheumatism

262

175

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Objective. To determine the safety of rituximab, to provide preliminary data regarding the potential efficacy of rituximab, and to investigate the effects of rituximab on autoimmunity and fibrosis in patients with diffuse cutaneous systemic sclerosis (dcSSc).Methods. Fifteen patients with dcSSc, all of whom experienced their first non-Raynaud's disease-associated disease manifestation within 18 months of trial entry, were recruited to receive 2 intravenous doses of rituximab (1,000 mg), administered 2 weeks apart. Safety, clinical, and exploratory outcomes were evaluated at baseline and at 6 months. The primary outcome was the change in the modified Rodnan skin thickness score (MRSS) at 6 months compared with baseline.Results. Adverse events included frequent infusion reactions and rare infections (urinary tract infection and dental abscess occurred in 1 patient each). The mean change in the MRSS between baseline and 6 months was not significant. Results of pulmonary function tests and other measures of major organ involvement were stable. The modest B cell infiltrates that were present in most skin biopsy specimens at baseline were completely depleted at 6 months in most patients. Autoantibody titers showed only modest and variable changes after treatment. Conclusion.In this pilot study, treatment with rituximab appeared to be safe and well tolerated among patients with dcSSc. Rituximab treatment resulted in both depletion of circulating B cells and depletion of dermal B cells but had little effect on the levels of SSc-associated autoantibodies. Rituximab treatment did not appear to result in a significant beneficial effect on skin disease. The potential efficacy of rituximab in other organs such as the lung could not be clearly evaluated in this small open-label trial.

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“…Density functional theory (DFT) calculations showed that the ground state of CrCO is the 7 A′ state (bent structure). The BDE calculated by using DFT is slightly higher than the experimental value . Thus, DFT appears to work well for the CrCO system.…”

Section: Introductionmentioning

confidence: 69%

“…In addition, the CO stretching vibrational frequency of CrCO in a matrix environment was also available . A large number of theoretical calculations were also performed to calculate the molecular properties of CrCO . Density functional theory (DFT) calculations showed that the ground state of CrCO is the 7 A′ state (bent structure).…”

Section: Introductionmentioning

confidence: 99%

High‐Level Ab Initio Calculations of Molecular Properties of Chromium Monocarbonyl, CrCO

Moon

Kim

2015

Bulletin Korean Chem Soc

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Chromium monocarbonyl (CrCO) is the simplest unsaturated transition metal carbonyl, and ab initio methods that include a dynamic electron correlation effect are necessary to calculate the molecular properties of CrCO. We employed post Hartree-Fock ab initio methods with various all-electron basis sets to calculate the molecular properties of CrCO including the molecular structures, vibrational frequencies, and bond dissociation energy. The methods including triple excitation and a quadruple-ζ level basis set are required to reasonably describe the molecular properties of CrCO. We found that the most efficient combination of theoretical method and basis set for this weakly interacting system is the unrestricted coupled-cluster singles and doubles with perturbative triples (UCCSD(T)) with the Sapporo-DKH3-QZP basis set.

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Density Functional and Ab Initio Study of Cr(CO)_n (n = 1−6) Complexes

Cited by 22 publications

References 104 publications

Photodissociation of group-6 hexacarbonyls: observation of coherent oscillations in an antisymmetric (pseudorotation) vibration in Mo(CO)5 and W(CO)5

Photodissociation of group-6 hexacarbonyls: observation of coherent oscillations in an antisymmetric (pseudorotation) vibration in Mo(CO)5 and W(CO)5

B cell depletion with rituximab in patients with diffuse cutaneous systemic sclerosis

High‐Level Ab Initio Calculations of Molecular Properties of Chromium Monocarbonyl, CrCO

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