title: Synthesis, structural elucidation, and application of a pyrazolylpyridine-molybdenum oxide composite as a heterogeneous catalyst for olefin epoxidation.
abstract: The reaction of [MoO(2)Cl(2)(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 [Mo(2)O(6)(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 (13)C CP MAS NMR spectroscopies and elemental analyses. In the asymmetric unit of 2, two crystallographically distinct Mo(6+) 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)[Mo(2)O(6)(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.
authors: Faculty of Science and Technology, Department of Chemistry, Biochemistry and Pharmacy, Centro de Investigação em Química do Algarve, University of the Algarve, Campus de Gambelas, 8005-136 Faro, Portugal.
authors: Sónia
authors: S
authors: Figueiredo
authors: Ana C
authors: AC
authors: Gomes
authors: Patrícia
authors: P
authors: Neves
authors: Tatiana R
authors: TR
authors: Amarante
authors: Filipe A Almeida
authors: FA
authors: Paz
authors: Rosário
authors: R
authors: Soares
authors: André D
authors: AD
authors: Lopes
authors: Anabela A
authors: AA
authors: Valente
authors: Martyn
authors: M
authors: Pillinger
authors: Isabel S
authors: IS
authors: Gonçalves