Premium
Iron Bispentazole Fe( η 5 ‐N 5 ) 2 , a Theoretically Predicted High‐Energy Compound: Structure, Bonding Analysis, Metal–Ligand Bond Strength and a Comparison with the Isoelectronic Ferrocene
Author(s) -
Lein Matthias,
Frunzke Jan,
Timoshkin Alexey,
Frenking Gernot
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20011001)7:19<4155::aid-chem4155>3.0.co;2-m
Subject(s) - ferrocene , chemistry , covalent bond , ionic bonding , crystallography , bond energy , ligand (biochemistry) , metal , bond dissociation energy , chemical bond , computational chemistry , molecule , ion , organic chemistry , dissociation (chemistry) , biochemistry , receptor , electrode , electrochemistry
Quantum‐chemical calculations with gradient‐corrected (B3LYP) density functional theory have been carried out for iron bispentazole and ferrocene. The calculations predict that Fe( η 5 ‐ N 5 ) 2 is a strongly bonded complex which has D 5d symmetry. The theoretically predicted total bond energy that yields Fe in the 5 D ground state and two pentazole ligands is D o =109.0 kcal mol −1 , which is only 29 kcal mol −1 less than the calculated bond energy of ferrocene ( D o =138.0 kcal mol −1 ; experimental: 158±2 kcal mol −1 ). The compound Fe( η 5 ‐N 5 ) 2 is 260.5 kcal mol −1 higher in energy than the experimentally known isomer Fe(N 2 ) 5 , but the bond energy of the latter ( D o =33.7 kcal mol −1 ) is much less. The energy decomposition analyses of Fe( η 5 ‐N 5 ) 2 and ferrocene show that the two compounds have similar bonding situations. The metal–ligand bonds are roughly half ionic and half covalent. The covalent bonding comes mainly from ( e 1g ) η 5 ‐N 5 − →Fe 2+ π‐donation. The previously suggested MO correlation diagram for ferrocene is nicely recovered by the Kohn–Sham orbitals. The calculated vibrational frequencies and IR intensities are reported.