cobalt · iron · metalates; phosphorus; sandwich complexes
Abstract :
[en] The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing
diphosphacyclobutadiene ligands is reported. Compounds [K([18]crown-6)(thf)2][Fe(h4-
P2C2tBu2)2] (K1), [K([18]crown-6)-(thf)2][Co(h4-P2C2tBu2)2] (K2), and [K([18]crown-6)(thf)2][Co(h4-
P2C2Ad2)2] (K3, Ad=adamantyl) were obtained from reactions of [K([18]crown-6)(thf)2][M(h4-C14H10)2]
(M=Fe, Co) with tBuC P (1, 2), or with AdC P (3). Neutral sandwiches [M(h4-P2C2tBu2)2] (4: M=Fe 5: M=
Co) were obtained by oxidizing 1 and 2 with [Cp2Fe]PF6. Cyclic voltammetry and spectro-electrochemistry indicates that the pairs [M(h4-P2C2tBu2)2] / [M(h4-P2C2tBu2)2] can be reversibly interconverted
by one electron oxidation and reduction, respectively. Complexes 1–5 were characterized by multinuclear
NMR, EPR (1 and 5), UV/Vis, and Mçssbauer spectroscopies (1 and 4), mass spectrometry (4 and 5), and microanalysis (1–3). The molecular structures of 1–5 were determined by usingX-ray crystallography. Essentially D2dsymmetric structures were found for all five complexes, which show the two 1,3-diphosphacyclobutadiene rings in a staggered orientation. Density functional theory calculations revealed the
importance of covalent metal–ligand p bonding in 1–5. Possible oxidation state assignments for the metal atoms are discussed.
Disciplines :
Chemistry
Author, co-author :
Wolf, Robert
Ehlers, Andreas W
Khusniyarov, Marat M
Hartl, Frantisek
de Bruin, Bas
Long, Gary J
Grandjean, Fernande ; Université de Liège - ULiège > Département de physique > Département de physique
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