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Imobilização de complexos organometálicos de Mo(II) e sua aplicação em catálise de oxidação
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Foram preparados complexos de Mo(II) do tipo [Mo(η3-C3H5)Br(CO)2(L-L)] a partirdo complexo precursor [Mo(η3-C3H5)Br(CO)2(MeCN)2] (A) dos ligandos 2(2'-piridil)imidazole (pim) e 2(2'-piridil)benzimidazole (pbim). Realizaram-se tentativas de imobilizar estes complexos em materiais lamelares, Mg / Al HTC, e materiais mesoporosos(MCM-41).Estas tentativas foram feitas seguindo dois procedimentos diferentes. O primeiro através da reacção directa do complexo via directa e o segundo fazendo reagir primeiro o ligando e só mais tarde adicionar o complexo precursor para ocorrer a síntese do complexo pretendido no interior do material. Realizaram-se ensaios catalíticos da epoxidação de olefinas, ciscicloocteno e estireno,na presença dos complexos 1 e 2 como catalisadores homogéneos, e os materiais lamelares HTC-A e HTC-B e os materiais mesoporosos MCM-Pr-pim-Mo (M5a), MCM-Pr*-pbim-Mo (M5b), MCM-Pr**-Mopim (M6a), MCM-Pr**-Mopbim (M6b) como catalisadores heterogéneos. Todos os complexos e materiais apresentaram actividade catalítica, no caso do ciscicloocteno, com selectividade em relação ao epóxido correspondente.
Complexes of the type [Mo((3-C3H5)Br(CO)2(L-L)] (L-L =bidentate nitrogen ligands) were prepared from the precursor [Mo((3-allyl)Br(CO)2(CH3CN)2] (A) by reaction with the ligands 2,2'-pyridylimidazole (pim), and 2,2'-pyridylbenzimidazole (pbim). Attempts were made to immobilize these complexes in Mg / Al HTC materials and mesoporous materials (MCM-41). These attempts were made by following two procedures. The first one is based on the reaction of the complexes in one step, and the second is based on the reaction of the ligands and then the addiction of the precursor complex [Mo(3-allyl)Br(CO)2(CH3CN)2] (A), in two steps. In both of the procedures the reaction to the material is made by deprotonation of the N-H groups of the ligands. All the complexes and materials prepared were tested as catalysts in the epoxidation of olefins with cyclooctene and styrene as substrates with all of them proving to have catalytic activity, and in the case of cyclooctene with selectivity towards the epoxide.
Complexes of the type [Mo((3-C3H5)Br(CO)2(L-L)] (L-L =bidentate nitrogen ligands) were prepared from the precursor [Mo((3-allyl)Br(CO)2(CH3CN)2] (A) by reaction with the ligands 2,2'-pyridylimidazole (pim), and 2,2'-pyridylbenzimidazole (pbim). Attempts were made to immobilize these complexes in Mg / Al HTC materials and mesoporous materials (MCM-41). These attempts were made by following two procedures. The first one is based on the reaction of the complexes in one step, and the second is based on the reaction of the ligands and then the addiction of the precursor complex [Mo(3-allyl)Br(CO)2(CH3CN)2] (A), in two steps. In both of the procedures the reaction to the material is made by deprotonation of the N-H groups of the ligands. All the complexes and materials prepared were tested as catalysts in the epoxidation of olefins with cyclooctene and styrene as substrates with all of them proving to have catalytic activity, and in the case of cyclooctene with selectivity towards the epoxide.
Descrição
Tese de mestrado, Química, 2008, Faculdade de Ciências, Universidade de Lisboa
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Química Teses de mestrado