ic301405r_si_003.cif (18.33 kB)
Synthesis, Structural Elucidation, and Application of a Pyrazolylpyridine–Molybdenum Oxide Composite as a Heterogeneous Catalyst for Olefin Epoxidation
dataset
posted on 2012-08-06, 00:00 authored by Sónia Figueiredo, Ana C. Gomes, Patrícia Neves, Tatiana
R. Amarante, Filipe A. Almeida
Paz, Rosário Soares, André D. Lopes, Anabela A. Valente, Martyn Pillinger, Isabel S. GonçalvesThe reaction of [MoO2Cl2(pypzEA)]
(1) (pypzEA = ethyl[3-(pyridin-2-yl)-1H-pyrazol-1-yl]acetate)
with water in a Teflon-lined stainless steel autoclave (100 °C)
or in an open reflux system leads to the isolation of the molybdenum
oxide/pyrazolylpyridine composite material [Mo2O6(HpypzA)] (2; HpypzA = [3-(pyridinium-2-yl)-1H-pyrazol-1-yl]acetate). The solid state structure of 2 was solved through single crystal and powder X-ray diffraction
analyses in conjunction with information derived from FT-IR and 13C CP MAS NMR spectroscopies and elemental analyses. In the
asymmetric unit of 2, two crystallographically distinct
Mo6+ centers are bridged by a syn,syn-carboxylate group of HpypzA. The periodic repetition
of these units along the a axis of the unit cell
leads to the formation of a one-dimensional composite polymer, ∞1[Mo2O6(HpypzA)].
The outstretched pyrazolylpyridine groups of adjacent polymers interdigitate
to form a zipper-like motif, generating strong onset π–π
contacts between adjacent rings of coordinated HpypzA molecules. The
composite oxide 2 is a stable heterogeneous catalyst
for liquid-phase olefin epoxidation.