A novel sandwich shaped {Co III2Co II12Mo V24} cluster with a Co II4 triangle encapsulated in two capped CoIIICo II4Mo V12O40 fragments

Abstract

A novel discrete {Co₁₄Mo₂₄} nanoscale cluster, {Co^III₂Co^II₁₀Cl₂(dpbt)₃(H₂O)₂[Co^IIMo^V₁₂O₃₁(CH₃O)₉]₂}·24CH₃OH (1) (here, dpbt = 5,5′-di(pyridin-2-yl)-3,3′-bi(1,2,4-triazole)), with a triangular Co₄ core encapsulated in two novel capped Co-substituted Keggin-type Co₅Mo₁₂O₄₀ anions, has been isolated from alkaline methanol solution. The high-resolution electrospray ionization mass spectrum (HRESI-MS) of microcrystalline 1 in MeOH/CH₂Cl₂ (v : v = 2 : 1) was recorded. Two prominent overlapping peaks in the range of m/z = 2740–2840 and 1820–1880 for the discrete fragments of [Co^III₂Co^II₁₂Mo^V₂₄O₆₂Cl₂(dpbt)₃(H₂O)₂(CH₃O)_x(OH)_18−x-2H]²⁻ (x = 9–18, F1) and [Co^III₂Co^II₁₂Mo^V₂₄O₆₂Cl₂(dpbt)₃(H₂O)₂(CH₃O)_x(OH)_19−x-2H]³⁻ (x = 6–13, F2), respectively, are obtained, confirming the {Co₁₄Mo₂₄} composition in 1. In addition, weak anti-ferromagnetic interactions in 1 are observed.