Results in Chemistry (Jun 2024)
Substitution reactivity of [Mo3(µ3-O)(µ3-CCH3)(µ-O2CCHCl2)6(CH3OH)3]O2CCHCl2 (Mo3) and the crystallization of a deca-molybdenum cluster [Mo10O10(μ3-O)8(μ-O)8(py)8](py)2 from Mo3 in pyridine
Abstract
By heating the trinuclear acetate-bridged molybdenum cluster, [Mo3(µ3-O)(µ3-CCH3)(µ-O2CCH3)6(H2O)3]+ in neat dichloroacetic acid for 4 h (T = 115 °C), a new trinuclear molybdenum cluster with chemical formula [Mo3(µ3-O)(µ3-CCH3)(µ-O2CCHCl2)6(CH3OH)3]+ (abbreviated as Mo3) was synthesized. After precipitation from solution with DI water and redissolution in methanol, red crystals formed after one week at 10 °C. To quantify the rate of substitution of the terminal methanol ligands, crystals of the trinuclear cluster were dissolved in 0.1 M pyridine‑d5 and monitored over time using 1H NMR (T = 297–310 K). The rate constant for substitution was found to be kobs298K = 1.87 × 10−4 s−1 and activation parameters equal toΔHobs‡ = 116 (±7) kJ/mol andΔSobs‡ = 74 (±23) J mol−1K−1. In an attempt to substitute the terminal methanol ligands using concentrated pyridine, a deca-molybdenum cluster with a cube-like polyoxomolybdate core was discovered ([Mo10O10(μ3-O)8(μ-O)8(py)8](py)2) (abbreviated as Mo10). Herein, we describe the synthesis, crystallographic data, and substitution reactivity of [Mo3(µ3-O)(µ3-CCH3)(µ-O2CCH2Cl2)6(CH3OH)3]O2CCHCl2 and report on the unexpected formation of [Mo10O10(μ3-O)8(μ-O)8(py)8](py)2 from neat pyridine.
