Infrared and 23Na Double Rotation Nuclear Magnetic Resonance Studies for Intrazeolite Anchoring of Rhodium Carbonyl Clusters

Abstract

The synthesis of intra-Na56Y zeolite anchoring of [Rh6(CO)12(μ3-CO)4] involves the deposition of [Rh(CO)2Cl]2 vapor into the Na56Y cavities followed by reductive carbonylation under a mixed CO and H2O atmosphere. The physicochemical characterization was based on a multianalytical approach, including Fourier transform infrared and 23Na double rotation (DOR) nuclear magnetic resonance (NMR) spectroscopies and CO gas chemisorption. The decarbonylated species of the intrazeolitic [Rh6(CO)12(μ3-CO)4] is proposed to contain a Rh4 cluster, which reacts with CO at low temperature, generating [Rh4(CO)9(μ2-CO)3] clusters, and with CO and H2O at high temperature to form [Rh6(CO)12(μ3-CO)4] clusters. 23Na DOR NMR signal shifts of the site II Na+ cations in the Na56Y supercages and infrared band shifts of bridging CO ligands in the [Rh6(CO)12(μ3-CO)4]−Na56Y provide complementary evidence for the anchoring of [Rh6(CO)12(μ3-CO)4] inside the supercages. These patterns suggest that a strong interaction occurs between the ...