Molecular Structures and Vibrational Frequencies of Iron Carbonyls:  Fe(CO)₅, Fe₂(CO)₉, and Fe₃(CO)₁₂

Abstract

Hybrid Hartree−Fock/density functional theory (HF/DFT) explicitly including all electrons has been employed to study the three iron carbonyls Fe(CO)5, Fe2(CO)9, and Fe3(CO)12. The geometries are fully optimized by the BP86 and B3LYP methods in conjunction with two basis sets, including as many as 507 contracted Gaussian functions for Fe3(CO)12. Our theoretical geometries and harmonic vibrational frequencies are carefully compared with available experimental results. For Fe3(CO)12 most of the fundamental vibrational frequencies have never been assigned experimenally. Several of the experimental assignments for Fe2(CO)9 and Fe3(CO)12 are dubious.

Reactions of Distibanes with [Fe2(CO)9]: Synthesis, Structure and DFT Calculations of [(Et2Sb)4Fe4(CO)14], [(nPr2Sb)4Fe3(CO)10], [{(Me3SiCH2)2Sb}4Fe2(CO)6], and [2‐(Me2NCH2)C6H4SbFe2(CO)8]

“…Our calculations with BLYP functional and TZ2P basis set on Fe(CO) 5 gave bond lengths with deviations between 1.8 -3.0 % with respect to the values found by X-ray diffraction on single crystal [19]. This result is consistent with calculations reported before [17,18]. The vibrational frequencies calculated for the CO stretching vibrations have errors ranging from 2.1 to 2.6 %, compared to experimental values [19].…”

“…The vibrational frequencies calculated for the CO stretching vibrations have errors ranging from 2.1 to 2.6 %, compared to experimental values [19]. These errors are comparable to those reported by Schaefer III et al [17], and by Jonas and Thiel [18].…”

“…The results compare well with experimental and theoretical results performed with different functionals and basis sets (ESI , Table S2 and ESI, Table S3) [17][18][19]. Our calculations with BLYP functional and TZ2P basis set on Fe(CO) 5 gave bond lengths with deviations between 1.8 -3.0 % with respect to the values found by X-ray diffraction on single crystal [19].…”

FTIR investigation of the equilibrium structure of osmium pentacarbonyl in alcohol solvents

“…However, the ground state D 3h symmetry of the MPC is only slightly lower in energy than the square pyramidal C 4v structure. This small energy barrier [30,[32][33][34][35] enables the MPC to undergo efficient Berry pseudorotation [36]. Several d 8 -systems that exhibit D 3h as well as C 4v conformation are known [37][38][39].…”

Solvent induced structural dynamics of ruthenium pentacarbonyl in benzene

“…In the gas-phase, the theoretically most stable geometry for M(CO) 5 is the trigonal-bipyramidal (D 3h ) structure [4]. The square pyramidal structure (C 4v ), however, lies very close in energy to the ground state [5][6][7][8]. The small barrier between these two most stable geometric structures facilitates an efficient Berry pseudorotation through the C 4v geometry [9].…”