Ab Initio Calculations of the Structures and Vibrational Spectra of Ethene Complexes

Abstract

To facilitate an objective comparison of the efficacy of the simulation of structural parameters and vibrational spectra of transition-metal complexes of commonly used ab initio methods, the geometries of the ethene complexes of Ni(0) and Ni(II) have been optimized using both ab initio and density functional theory (DFT) calculations and a wide variety of basis sets. The harmonic vibrational spectra of [Ni(C2H4)] and [Ni(C2H4)]2+ have been evaluated from the optimized geometries at Hartree−Fock, post-Hartree−Fock Møller−Plesset perturbation theory, MP2, and a range of DFT functionals. Upon comparison with experimental data, it has been found that hybrid DFT functionals, specifically B3-LYP, afford the most accurate fit to the experimental data. This is especially the case when using the all-electron DZVP basis set, which provides highly accurate results. The use of the effective core potential LanL2DZ basis set has been found to achieve a comparable level of accuracy to the DZVP basis set, at a fraction of the computational efficiency. Extension of these calculations to ethene complexes of other transition metals has revealed trends in their structures and vibrational spectra.

The Electronic Structure of the Tris(ethylene) Complexes [M(C2H4)3] (M=Ni, Pd, and Pt): A Combined Experimental and Theoretical Study

“…Calculations on the B3LYP level are not able to reproduce this trend in the wavenumbers, presumably because the mixing between nA C H T U N G T R E N N U N G (C À C) and dA C H T U N G T R E N N U N G (CH 2 ) is underestimated. [32] In summary, the accumulated data thus confirm, in agreement to earlier accounts, that the wavenumber of the n 2 (a) mode should not be taken as indicator of the bond strength.…”

“…[32] However, the experimentally observed wavenumbers of the stretching mode nA C H T U N G T R E N N U N G (CÀC) follow the trend [Co- Table 4). Calculations on the B3LYP level are not able to reproduce this trend in the wavenumbers, presumably because the mixing between nA C H T U N G T R E N N U N G (C À C) and dA C H T U N G T R E N N U N G (CH 2 ) is underestimated.…”

“…1453 [a] 1177 [39] [AlA C H T U N G T R E N N U N G (C 2 H 4 )] 1623 1340 [40] [InA C H T U N G T R E N N U N G (C 2 H 4 )] 1488 1201 [41] [FeA C H T U N G T R E N N U N G (C 2 H 4 ) 2 ] 1491 [a] 1221(e) [32] [CoA C H T U N G T R E N N U N G (C 2 H 4 )] 1504 1224 [33] [CoA C H T U N G T R E N N U N G (C 2 H 4 ) 2 ] 1465 1222 [33] [NiA C H T U N G T R E N N U N G (C 2 H 4 )] 1468 1166 [34] [NiA C H T U N G T R E N N U N G (C 2 H 4 ) 3 ] [b] 1512 [35] [NiA C H T U N G T R E N N U N G (C 2 H 4 ) 3 ] 1512/1516 1242 (IR/R) [11,12] [PdA C H T U N G T R E N N U N G (C 2 H 4 )] 1505 1216 [36] [PdA C H T U N G T R E N N U N G (C 2 H 4 ) 3 ] 1525/1531 1266/1256 this work [PtA C H T U N G T R E N N U N G (C 2 H 4 ) 3 ] [b] 1503/1501 [35] [CuA C H T U N G T R E N N U N G (C 2 H 4 )] 1475 1156/1138 (IR) [37] [CuA C H T U N G T R E N N U N G (C 2 H 4 ) 2 ] 1505 1228 (IR) [37] [CuA C H T U N G T R E N N U N G (C 2 H 4 ) 3 ] 1525 1252 [37] [AgA C H T U N G T R E N N U N G (C 2 H 4 )] 1476 1152/1132 (IR) [38] [AuA C H T U N G T R E N N U N G (C 2 H 4 )] 1476 1144/1135 (IR) [38] [a] Calculated value on the basis of a force field. [b] Solutions in petroleum ether.…”

Ethylene polymerization catalyzed by a cyclophane-diimine-based Ni(II) complex, a quantum/molecular mechanic study

“…Also, all energies obtained included the Zero Point Energy (ZPE) correction. It worth to remark that this level of calculation has been adopted by other groups [32,33], as well in a former work of our group [18,34], with good quality of geometries, and energies of the structures obtained. To understand the solvent effect on olefin polymerization by Ni-cyclophane complex was accomplished single point calculations on molecular structures 1, 2, 3 and 4 (optimized by methodology above described) employing the IEFPCM model (Integral-Equation-Formalism Polarizable Continuum Model) containing toluene as solvent.…”

Lead‐enhanced gas‐phase stability of multiply charged EDTA anions: a combined experimental and theoretical study

“…[35][36][37] This ECP has been demonstrated to provide reliable results for a variety of transition metal complexes [38,39] and Pb(II) coordination compounds. Compared with the all-electron basis sets, the use of ECPs can be capable of achieving a comparable level of accuracy to all-electron basis set of double-zeta split-valence polarization (DZVP), [40] accounting for its relativistic effects to some extent. It is believed that relativistic effects will become especially important for the heavy metal atoms.…”