Computational study of the energetics of 3Fe(CO)4, 1Fe(CO)4 and 1Fe(CO)4(L), L = Xe, CH4, H2 and CO.
Large basis CCSD(T) calculations are used to calculate the energetics of 3Fe(CO)4, 1Fe(CO)4 and 1Fe(CO)4(L), L = Xe, CH4, H2 and CO. . The relative energy of the excited singlet state of Fe(CO)4 with respect to the ground triplet state is not known experimentally, and various lower levels of theory predict very different results. Upon extrapolating to the infinite basis set limit, and including corrections for core-core and core-valence correlation, scalar relativity, and multi-reference character of the wavefunction, the best CCSD(T) estimate for the spin-state splitting in iron tetracarbonyl is 2 kcal mol(-1). Calculation of the dissociation energy of 1Fe(CO)4(L) into singlet fragments, taken together with known experimental behaviour of triplet Fe(CO)4, provides independent evidence for the fact that the spin-state splitting is smaller than 3 kcal mol(-1). These calculations highlight some of the challenges involved in benchmark calculations on transition metal containing systems.
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
José-Luis
JL
Carreón-Macedo
Jeremy N
JN
Harvey
D002248:Carbon Monoxide / Q000737:chemistry*; D003198:Computer Simulation; D006859:Hydrogen / Q000737:chemistry; D058085:Iron Compounds / Q000737:chemistry*; D008024:Ligands; D008697:Methane / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D013816:Thermodynamics; D014978:Xenon / Q000737:chemistry*
D058085:Iron Compounds; D008024:Ligands; D009942:Organometallic Compounds; D014978:Xenon; D002248:Carbon Monoxide; D006859:Hydrogen; D008697:Methane