Calculation of the enthalpies of formation for transition metal complexes

Cundari, Thomas R.; Ruiz, Héctor A.; Grimes, Tom; Steyl, Gideon; Waters, Aubri; Wilson, Angela K.

doi:10.1016/j.cplett.2004.11.021

Cited by 46 publications

(53 citation statements)

References 27 publications

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“…First, it needs to be mentioned that the choice of the LANL2DZ basis set is dictated by the limited availability of high-quality atomic orbital basis sets for the zinc atom. The LANL2DZ basis set outperforms the popular relativistic effective core potentials of Stevens et al [77] and the relativistic effective core potentials of Dolg and coworkers [78,79] to calculate the structural characteristics [80][81][82] and gas-phase formation enthalpies [83] of transition metal complexes at both MP2 and DFT levels. Moreover, it has been found that all-electron basis sets for heavy metals such as LANL2DZ give the rise to a large BSSE [84].…”

Section: Bsse Effectmentioning

confidence: 99%

Adsorption of RDX and TATP on IRMOF-1: an ab initio study

2009

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The adsorption of 1,3,5-trinitro-s-triazine (RDX) and triacetone triperoxide (TATP) on representative fragments of metal organic framework (IRMOF-1) was studied at the B3LYP/6-31G(d) level of theory. For examined adsorbates several possible adsorption positions toward the IRMOF-1 fragments were found. The adsorption strength of the adsorbate on IRMOF-1 is largely affected by the geometry of the active site of IRMOF-1 which controls the orientation of the target molecule with respect to the IRMOF-1 fragment. The calculations show that the adsorption on these fragments occurs due to the formation of hydrogen bonds between the molecular C-H groups and the oxygen atoms of IRMOF-1. The RDX and TATP molecules are the most strongly adsorbed on the linker fragment of IRMOF-1. This type of adsorption results in the polarization of RDX and TATP on the IRMOF-1 fragments. The interaction energy of two most stable RDX-, and TATP-IRMOF-1 adsorption systems are -9.8 and -12.8 kcal/mol, respectively. It can be concluded that the 1,4-benzenedicarboxylate site of IRMOF-1 shows the stronger molecular adsorption of RDX and TATP than the site containing [Zn 4 O(CO 2 ) 6 ] and also it is characterized by higher reactivity than the other considered sites. The binding of studied explosive molecules to IRMOF-1 consists of interplay between attractive interactions between the target molecule and MOF as well as the shielding by the IRMOF-1 fragment induced by the molecular adsorption. The relative importance of these effects depends on the chemical nature, the size, and the shape of the molecule and MOF. Small-size molecules require smaller space for the adsorption and also they are less shielded by the sizeable adsorbent. So they interact better when adsorbed on larger IRMOF-1 fragment. On the other side, larger molecules show higher adsorption strength with small fragments of IRMOF-1.

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Section: Bsse Effectmentioning

confidence: 99%

Adsorption of RDX and TATP on IRMOF-1: an ab initio study

2009

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“…Another example of ccCA-tm performing unsatisfactorily is in the modeling of larger TM carbonyls; for example, for Ni(CO) 4 , Fe(CO) 5 , and Cr(CO) 6 , ccCA-tm shows errors of 30-100 kcal mol -1 . While consolation may be taken in the fact that the ccCA-tm deviations for carbonyl systems are still much smaller than those obtained using standard DFT/ECP approaches, 45 further work is necessary to determine whether the disagreement is caused by deterioration of ccCA-tm with respect to increasing molecular size or by something inherent in carbonyl or related π-acid ligands. Our initial observations suggest an intriguing origin for these discrepancies, as a more sophisticated treatment of the corevalence electron correlation substantially improves the calculated ∆H f°f or carbonyl complexes.…”

Section: ∆E(cv) ) E[ccsd(t)](fc1) -E[ccsd(t)] (110)mentioning

confidence: 99%

“…Using the average experimental σ of (2-3 kcal mol -1 as an initial estimate of "TM chemical accuracy," we find that ccCA-tm thus performs adequately for this test set and is quite superior to DFT-based methods. 38, 45 Cognizance must be taken of the potential for issues in the modeling of 3d TM complexes that arise from the underlying perturbation theory assumptions of many of the ccCA-tm computations. Such computations may not provide an accurate description of both static and dynamic electron correlation, and problems can arise from the inherently multireference nature of many TM species.…”

Section: ∆E(cv) ) E[ccsd(t)](fc1) -E[ccsd(t)] (110)mentioning

confidence: 99%

“…A recent contribution in our group 45 showed calculated errors in gas-phase enthalpies of formation for a set of 26 TM complexes with DFT and effective-core potential basis sets to be as large as 240 kcal mol -1 ! The aforementioned study by Truhlar and co-workers 39 evaluated many different functionals for an assortment of small metal molecules and cations, including some main group metal compounds, and found the G96LYP functional and their newly developed MPWLYP1M and M05 46 functionals performed well.…”

Section: Introductionmentioning

confidence: 99%

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Quantitative Computational Thermochemistry of Transition Metal Species

et al. 2007

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The correlation consistent Composite Approach (ccCA), which has been shown to achieve chemical accuracy ((1 kcal mol -1 ) for a large benchmark set of main group and s-block metal compounds, is used to compute enthalpies of formation for a set of 17 3d transition metal species. The training set includes a variety of metals, ligands, and bonding types. Using the correlation consistent basis sets for the 3d transition metals, we find that gas-phase enthalpies of formation can be efficiently calculated for inorganic and organometallic molecules with ccCA. However, until the reliability of gas-phase transition metal thermochemistry is improved, both experimentally and theoretically, a large experimental training set where uncertainties are near (1 kcal mol -1 (akin to commonly used main group benchmarking sets) remains an ambitious goal. For now, an average deviation of (3 kcal mol -1 appears to be the initial goal of "chemical accuracy" for ab initio transition metal model chemistries. The ccCA is also compared to a more robust but relatively expensive composite approach primarily utilizing large basis set coupled cluster computations. For a smaller training set of eight molecules, ccCA has a mean absolute deviation (MAD) of 3.4 kcal mol -1 versus the large basis set coupled-clusterbased model chemistry, which has a MAD of 3.1 kcal mol -1 . However, the agreement for transition metal complexes is more system dependent than observed in previous benchmark studies of composite methods and main group compounds.

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“…It provides an effective way to reduce computational expense. On the other hand, the LANL2DZ basis set outperforms the popular relativistic effective core potentials of Stevens et al (1992) and the relativistic effective core potentials of Dolg (2000), in calculations involving the structural characteristics (Day et al, 2000;Widjaja and Musgravea, 2002) and gas-phase formation enthalpies (Cundari et al, 2005) of transition metal complexes at the DFT level.…”

Section: Computational Detailsmentioning

confidence: 98%