ABSTRACT
The first examples of samarium, europium, and ytterbium complexes with 3,6-di-tert-butyl-o-benzoquinone(3,6-dbbq) in the form of catecholate have been obtained by reactions of the quinone with the corresponding lanthanocenes, [LnCp2*(thf)n] (n = 1 or 2) in solution. In the course of the reactions lanthanide ions lose one or two Cp* ligands, which take part in reduction of a quinone molecule into a catecholate anion (dbcat, 2(-)). As a result of the reactions, Sm and Yb clearly yield dimeric complexes[(LnCp*)2(dbcat)2], where each Ln ion loses one Cp* ligand. Eu forms a trimeric complex [(EuCp*)-(Eu·thf)2(dbcat)3], in which one Eu ion is coordinated by one Cp* ligand, while two Eu ions have lost all Cp* ligands and are coordinated by THF molecules instead. Magnetic properties corroborate the assignment of oxidation states made on the basis of single-crystal X-ray diffraction: all the quinone ligands are present in the catecholate state; both Sm/Yb ions in the dimers are in the +3 oxidation state, whereas the Eu trimer contains two Eu(II) and one Eu(III) ions. Cyclovoltammetry studies show the presence of two reversible oxidation waves for all complexes, presumably concerned with the redox transitions of the dbcat ligands.
ABSTRACT
The sterically hindered title complex, [Fe(3)Te(2)(C(36)H(40)N(2))(CO)(7)], was obtained by substitution of two carbonyl groups in the [Fe(3)(µ(3)-Te)(2)(CO)(9)] cluster by the bulky redox-active N,N'-bis(2,6-diisopropylphenyl)acenaphthene-1,2-diimine (dpp-BIAN) ligand. The asymmetric unit contains two molecules of the same geometry. The C=N bond lengths in dpp-BIAN indicate a rather low level of electron transfer from the cluster core to the dpp-BIAN ligand.
Subject(s)
Ferrous Compounds/chemistry , Iron/chemistry , Crystallography, X-Ray , Electrons , Ligands , Models, Molecular , Molecular StructureABSTRACT
Reaction between [Fe2(µ-S2)(CO)6] and [Ca(thf)4(dpp-BIAN)] [dpp-BIAN = 1,2-bis-(2,6-diisopropyl-phenyl-imino)-acenaphthene and thf = tetra-hydro-furan] proceeds as a redox process via a two-electron reduction of [Fe2(µ-S2)(CO)6] and a two-electron oxidation of (dpp-BIAN)(2-), resulting in the formation of the title heterometallic trinuclear cluster, [CaFe2(µ3-S)2(C4H8O)4(CO)6], and neutral dpp-BIAN. In the cluster, the Ca(II) atom is connected to two S atoms of an Fe2S2 core [Ca-S = 2.7463â (8) and 2.7523â (8)â Å]. No Fe-Ca bonds are formed [Feâ¯Ca = 3.6708â (6) and 3.5802â (6)â Å]. There are five close C-Hâ¯O-C contacts in the crystal structure.
