Flexibility in the Coordination Chemistry of the 2,3-Dimethylindolide Ligand with Potassium, Yttrium, and Samarium

Abstract

The coordination chemistry of the 2,3-dimethylindolide anion (DMI), (Me(2)C(8)H(4)N)(-), with potassium, yttrium, and samarium ions is described. In the potassium salt [K(DMI)(THF)](n), 1, prepared from Me(2)C(8)H(4)NH and KH in THF, the dimethylindole anion binds and bridges potassium ions in three different binding modes, namely eta(1), eta(3), and eta(5), to form a two-dimensional extended structure. In the dimethoxyethane (DME) adduct [K(DMI)(DME)(2)](2), 2, prepared by crystallizing a sample of 1 from DME, DMI exists as a mu-eta(1):eta(1) ligand. Compound 1 reacts with SmI(2)(THF)(4) in THF to form the distorted octahedral complex trans-(DMI)(2)Sm(THF)(4), 3, in which the dimethyindolide anions are bound in the eta(1) mode to samarium. Reaction of 2,3-dimethylindole with Y(CH(2)SiMe(3))(3)(THF)(2) afforded the amide complex (DMI)(3)Y(THF)(2), 4, in which the dimethylindolide anions are also bound in the eta(1) mode to yttrium. Compound 1 also reacts with (C(5)Me(5))(2)LnCl(2)K(THF)(2) (Ln = Sm, Y) to form unsolvated amide complexes (C(5)Me(5))(2)Ln(DMI) (Ln = Sm, 5; Y, 6), in which DMI attaches primarily through nitrogen, although the edge of the arene ring is oriented toward the metals at long distances.

Reactivity of 1,3-Disubstituted Indoles with Lithium Compounds: Substituents and Solvents Effects on Coordination and Reactivity of Resulting 1,3-Disubstituted-2-Indolyl Lithium Complexes

“…Indole and its derivatives, for their electron-rich properties, have been widely used in transition organometallic chemistry with the finding of multihapto-binding modes (Figure ). − Indolide-based anionic ligands commonly bind to most metals in the η 1 and μ 2 -η 1 :η 1 modes through the electron-rich nitrogen atom . In some circumstances, the η 5 bonding modes through the electron-delocalized five-membered heterocyclic ring have been observed in transition metal and s block metal complexes, which holds promise for indolide-containing anions to functionalize as alternatives to traditionally used indenyl ligands.…”

SmI2-mediated dimerization of indolylbutenones and synthesis of the myxobacterial natural product indiacen B

“…A possible reason for our findings could be the capability of a deprotonated indole ring to engage into complexation with Sm(III) formed by reduction of the enone moiety ( Scheme 2 ), leading to a gauche -type orientation of the indole moieties, as shown in structures 10 and 11 . It is known that anionic indolide can form complexes with Sm(II) and Sm(III) [ 27 – 28 ]. Thus, the indole NH group (p K a about 21 in DMSO) should be able to serve as a stoichiometric proton source that, after β,β'-coupling, would convert one of the Sm(III) enolates to the ketone.…”

Rare‐Earth Metal Alkyl Complexes with 3‐Arylamido‐Functionalized Indolyl Ligands: Synthesis, Characterization and Reactivity†

“…indolide acted as a monoanionic species coordinated to Yb II in η 1 and μ ‐ η 1 : η 1 bonding modes, respectively . Similarly, monoanionic precursor of 2,3‐dimethylindolide has been used in the preparation of yttrium and samarium complexes . 7‐Imino‐functionalized indolyl ligand was prepared by Cui's group, and the corresponding dialkyl complexes showed the controlled polymerization of isoprene in the presence of appropriate aluminum and borate compounds, however, the monoalkyl complexes bearing the same ligand are inert for the isoprene polymerization .…”