Activity of Mo(II) allylic complexes supported in MCM-41 as oxidation catalysts precursors |
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| Authors: | Marta S Saraiva Newton L Dias Filho Carla D Nunes Pedro D Vaz Teresa G Nunes Maria José Calhorda |
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| Affiliation: | 1. Departamento de Química e Bioquímica, CQB, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal;2. UNESP – Universidade Estadual Paulista, Faculdade de Engenharia de Ilha Solteira, Departamento de Física e Química, Avenue Brazil Centro, 56 CEP 15385-000, Ilha Solteira, SP, Brazil;3. Centro de Química Estrutural, Instituto Superior Técnico, Avenue Rovisco Pais, 1049-001 Lisboa, Portugal;1. Department of Chemistry, Gauhati University, Guwahati 781014, Assam, India;2. Department of Chemistry, Arya Vidyapeeth College, Guwahati 781016, Assam, India;1. Departamento de Química e Bioquímica, CQB, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa, Portugal;2. Centro de Química Estrutural, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal |
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| Abstract: | Mo(η3-C3H5)X(CO)2(NCCH3)2] (X = Br, 1a; X = Cl, 1b) complexes reacted with the bidentate ligand RN C(Ph)–C(Ph)NR, R = (CH2)2CH3 (DAB, 2) affording Mo(η3-C3H5)X(CO)2(DAB)] (X = Br, 4a; X = Cl, 4b), which were characterized by elemental analysis, FTIR and 1H and 13C NMR spectroscopy. The modified silylated ligand RNC(Ph) C(Ph)NR, R = (CH2)3Si(OCH2CH3)3 (DAB–Si, 3), was used to immobilize the two complexes in MCM-41 (MCM) mesoporous silica. The new materials were characterized by powder X-ray diffraction, N2 adsorption analysis, FTIR and 29Si and 13C CPMAS solid state NMR spectroscopy. Both the materials and the complexes were tested in the oxidation of cyclooctene and styrene and behaved as active catalyst precursors for cyclooctene and styrene epoxidation with TBHP (t-butylhydroperoxide), leading selectively to epoxides with high conversions and TOFs. Although the homogeneous systems reach 100% conversion of cyclooctene and slightly less for styrene, the loss of catalytic activity in the heterogeneous systems is small, with a 98% conversion of styrene achieved by the chloride containing material. |
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