Convenient syntheses and structural characterizations of mono-substituted alkylimido hexamolybdates: [Mo6O18(NR)]2− (R = Me, Et, n-Pr, i-Pr, n-Bu, t-Bu, Cy, Hex, Ode)

Abstract

Monofunctionalized alkylimido derivatives of hexamolybdate, (Bu₄N)₂[Mo₆O₁₈(≡N–R)] (R = methyl, Me; ethyl, Et; n-propyl, n-Pr; i-propyl, i-Pr; n-butyl, n-Bu; t-butyl, t-Bu; cyclohexyl, Cy; n-hexyl, Hex; and n-octadecyl, Ode), have been prepared in high purity and good yield by the reaction of [Bu₄N]₄[α-Mo₈O₂₆] with appropriate aliphatic amine hydrochlorides in anhydrous acetonitrile, using N,N′-dicyclohexylcarbodiimide (DCC) as the dehydrating agent. Eight compounds have been determined by single crystal X-ray diffraction analysis and all compounds have been studied with ¹H-NMR, IR, UV-vis, ESI mass spectrometry and cyclic voltammetry. A structural and ¹H-NMR study show β hydrogen atoms of those alkylimido derivatives of hexamolybdate have strong Brønsted acidity compared to the hydrogen atoms in other positions.