Vibrational scaling factors for transition metal carbonyls

Abstract

Vibrational frequencies for a selected set of transition metal carbonyl complexes are computed with various forms of density functional theory (B3LYP, BP86, M06, M06-L), employing several different basis sets. The computed frequencies for the carbonyl stretches are compared to the experimental values obtained from gas phase infrared spectra of isolated neutrals and ions. Recommended carbonyl-stretch scaling factors which are developed vary significantly for different functionals, but there is little variation with basis set. Scaled frequencies compared to experimental spectra for cobalt and tantalum carbonyl cations reveal additional variations in multiplet patterns and relative band intensities for different functionals.

VIBRATIONAL SCALING FACTORS FOR Rh(I) CARBONYL COMPOUNDS IN HOMOGENEOUS CATALYSIS

“…Comparing the computational times of both of the methods, BP86 is shown to be much more attractive requiring much less computational time and providing better accuracy without and same accuracy after scaling. As shown before [16] the scaling factors vary insignificantly with the basis set, which makes our derived scale factors also applicable to other basis sets. Метал карбонилните комплекси се важно семејство на катализатори во хомогените индустриски процеси.…”

“…Our scaling factors are in line with those from Assefa et al of 1.012 and 0.968 for BP86/def2-TZVP and B3LYP/def2-TZVP, respectively. These scaling factors were derived for different transition metal homoleptic carbonyl complexes but not for Rh complexes [16].…”

“…Studies show the scaling factors for high and low frequencies can be very different which justifies the use of dual scaling [11]. There are published carbonyl frequency scaling factors for Fe-Fe complexes [15], or for diverse transition metal homoleptic carbonyls [16]. Nevertheless, the systematic errors arising from the basis sets of different transition metals are different.…”

How does the Environment Influence a Given Cation? A Systematic Investigation of [Co(CO)5]+ in Gas Phase, Solution, and Solid State

“…As a reference for later discussions, we performed calculations based on the (RI‐)B3LYP‐D3/def2‐TZVPP level of theory for the TBP and SP structures of [Co(CO) 5 ] + . This level of theory emerged from others, as well as own work, as being very reliable for this system . As is typical for a transition state structure, the vibrational analysis gave rise to an imaginary frequency ( i 45 cm −1 ) for the SP.…”

“…Nevertheless, we discuss the real ν(CO) frequencies of the SP, keeping in mind that the vibrational modes are orthogonal to each other and that the curvature of the imaginary frequency mode is very flat, so that the Berry pseudorotation is on another timescale to the ν(CO) frequencies. Our computed structures, along with the geometric data and vibrational spectra (scaled by a factor of 0.968) in the carbonyl region, are shown in Figure . The corresponding ν(CO) bands (scaled accordingly) are listed in Table .…”