Synthesis of new donor/acceptor η5-cyclopentadienyl and η5-indenyliron(II) complexes with p-benzonitrile derivatives. Crystal structures of [Fe(η5-C5H5)(CO)(P(OC6H5)3)(p-NCC6H4NO2)][BF4]·CH2Cl2 and [Fe(η5-C9H7)(CO)(P(OC6H5)3)(p-NCC6H4NO2)][BF4]

Abstract

New complexes of the type [Fe(h 5-Cp or Ind)(L)(L%)(p-NCR)][BF 4 ] (L, L%= CO, P(OC 6 H 5) 3 , P(C 6 H 5) 3 ; R=C 6 H 4 N(CH 3) 2 , C 6 H 4 NO 2 , (E)-C(H) C(H)C 6 H 4 NO 2 , (E)-C(H) C(H)C 6 H 4 N(CH 3) 2) have been synthesised and characterised. Spectroscopic data were analysed in order to evaluate the tuning of the electronic density at the metal centre and the extension of the p-delocalisation on the molecule, due to the presence of coligands with different acceptor/donor abilities. The structures of two complexes [Fe(h 5-C 5 H 5)(CO)(P(OC 6 H 5) 3)(p-NCC 6 H 4 NO 2)][BF 4 ] and [Fe(h 5-C 9 H 7)(CO)(P(OC 6 H 5) 3)(p-NCC 6 H 4 NO 2)][BF 4 ] were determined by X-ray crystallographic analysis. The compounds crystallised in the centrosymmetric space groups P1(and P2 1 /n, respectively. Bond distances within the nitrile ligand are discussed in order to evaluate the nature of iron-nitrile bonding in these complexes.

Switchable Nonlinear Optical Properties of η5-Monocyclopentadienylmetal Complexes: A DFT Approach

“…The angles and bond lengths around the metal centers and within the thienyl system for both ligand and organometallic complexes are consistent with experimental crystal data for parent iron(II) and ruthenium(II) thiophene derivatives , and other η 5 -monocyclopentadienylmetal nitriles. − In general, the use of B3LYP and M06 functionals originates relatively similar bond lengths and angles, in particular, within the conjugate thienyl nitrile framework. CAM-B3LYP provides shorter bond lengths in the case of multiple bonds and stretched bond lengths for single bonds.…”

“…The changing of the structural feature of the molecules studied in this work, in which the organometallic moiety becomes an electron acceptor, reveals their inadequacy for an efficient NLO-switching by reduction means because they are known as strong electron donors. In fact, improved hyperpolarizabilities are expected when these organometallic moieties behaves as a donors and are coupled with strong electron acceptors as was observed in largely studied D-π-A molecular feature complexes. ,,− This behavior can be emphasized if we consider the study of the redox-switchable second-order nonlinear optical responses of rhodium(I)-9,10-phenanthrenediimine and noninnocent ruthenium complexes, for which the increase in second-order NLO response upon reduction has been attributed to MLCT transitions. Thus, significant changes are not expected on the quadratic hyperpolarizabilities of the complexes studied in this work upon reduction when compared to those observed upon oxidation in which the organometallic moiety behaves as a donor.…”

Regioselective reactions of electrophilic iron dicarbonyl cations, [(η5-C5R5)(CO)2Fe]+ (R = H, CH3) with heterofunctional amine ligands

“…In addition, the IR spectra of the dinuclear complexes exhibited two bands in the CeO stretching region within the range 2032e2081 cm À1 , which are assignable to the terminal carbonyls on the cyano side, because nitriles are weakly bound to the metal. These values are in agreement with reported data for related nitrile coordinated cyclopentadienyliron dicarbonyl complexes [34,37,38]. The two other expected bands corresponding to terminal carbonyls on the amine side were found to lie within the range 1987e2040 cm À1 , which is also in good agreement with data reported for the related alkylamine complexes [20,22,29].…”