Catalytic Activity of Molybdenum(II) Complexes in Homogeneous and Heterogeneous Conditions

Abstract

The new complexes [MoBr(η3-C3H5)(CO)2(L)2] (C1) and [MX2(CO)3(L)2] (M = Mo(II), X = I (C2); M = Mo(II), X = Br (C3); M = W(II), X = I (C4); M = W(II), X = Br (C5)) were synthesized by reaction of 2-amino-1,3,4-thiadiazole (L) with [MoBr(η3-C3H5)(CO)2(NCCH3)2] (1), [MoI2(CO)3(CH3CN)2](M = Mo (2); M = W (4)), or [MoBr2(CO)3(CH3CN)2](M = Mo (3); M = W (5)) in 2:1 ratio. The five complexes were immobilized in MCM-41, yielding the materials MCM-Cn (n = 1–5), and C1 was also immobilized in silica gel (Silica-C1) and in a polyhedral oligomeric silsesquioxane (Cube-C1). Complexes and materials were fully characterized by spectroscopic techniques and elemental analysis. DFT calculations showed that several C1 isomers should coexist. The as synthesized and supported complexes were tested as catalysts on the oxidation of geraniol, cis-hex-3-en-1-ol, trans-hex-3-en-1-ol, (S)-limonene, and 1-octene. The conversions and TOF significantly depend on the complex and the nature of the substrate. The general conclusions are...