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Dombrowski JP, Ziegler MS, Phadke NM, Mansoor E, Levine DS, Witzke RJ, Head-Gordon M, Bell AT, Tilley TD. Siloxyaluminate and Siloxygallate Complexes as Models for Framework and Partially Hydrolyzed Framework Sites in Zeolites and Zeotypes. Chemistry 2021; 27:307-315. [PMID: 32926472 DOI: 10.1002/chem.202002926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/02/2020] [Indexed: 11/07/2022]
Abstract
Anionic molecular models for nonhydrolyzed and partially hydrolyzed aluminum and gallium framework sites on silica, M[OSi(OtBu)3 ]4 - and HOM[OSi(OtBu)3 ]3 - (where M=Al or Ga), were synthesized from anionic chlorides Li{M[OSi(OtBu)3 ]3 Cl} in salt metathesis reactions. Sequestration of lithium cations with [12]crown-4 afforded charge-separated ion pairs composed of monomeric anions M[OSi(OtBu)3 ]4 - with outer-sphere [([12]crown-4)2 Li]+ cations, and hydroxides {HOM[OSi(OtBu)3 ]3 } with pendant [([12]crown-4)Li]+ cations. These molecular models were characterized by single-crystal X-ray diffraction, vibrational spectroscopy, mass spectrometry and NMR spectroscopy. Upon treatment of monomeric [([12]crown-4)Li]{HOM[OSi(OtBu)3 ]3 } complexes with benzyl alcohol, benzyloxide complexes were formed, modeling a possible pathway for the formation of active sites for Meerwin-Ponndorf-Verley (MPV) transfer hydrogenations with Al/Ga-doped silica catalysts.
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Affiliation(s)
- James P Dombrowski
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Micah S Ziegler
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Neelay M Phadke
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Erum Mansoor
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA.,Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Daniel S Levine
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.,Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Ryan J Witzke
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Martin Head-Gordon
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.,Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Alexis T Bell
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.,Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - T Don Tilley
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
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Moreno-Martínez VCA, Martı Nez-Otero D, Meza-González B, Cortéz-Guzmán F, Jancik V. Aluminum-Triggered Condensation of Vicinal Silicate Groups into a Bicyclic Alumosilicate. Inorg Chem 2020; 59:6849-6856. [PMID: 32338499 DOI: 10.1021/acs.inorgchem.0c00224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The molecular alumosilicates AlL{OSi(OtBu)2O}[OSi{(μ3-O)(MR2)2(μ-OtBu)}(OtBu)] (L = HC[CMeNAr]2-, where M = Al, R = Me (2), Et (3), and iBu (4) and M = Ga, R = Me (5)) were obtained from the reaction of AlL{OSi(OtBu)2(OH)}2 (1) with 1 or 2 equiv of the respective organometallic precursor. These compounds have a central bicyclic inorganic core formed by a six-membered AlSi2O3 alumosilicate ring with a Si-O-Si unit connected via a Si-O bond to a four-membered Al2O2 alumoxane ring. These compounds are formed even though 1 is specifically designed to yield 4R alumosilicate rings that would obey the Löweinstein's and Dempsey's rules about concatenation between silicon and aluminum tetrahedra in alumosilicates. We propose a mechanism for this rearrangement, based on the experimental evidence and density functional theory calculations, that involves a κ3μ2 coordination of a silicate unit to two AlMe2 groups, which weakens one Si-O bond and explains how aluminum atoms can cleave Si-O bonds. Furthermore, formation of the products experimentally confirms the theory that Al-O-Al groups can exist in alumosilicates if the oxygen atom belongs to an OH moiety.
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Affiliation(s)
- Vı Ctor Augusto Moreno-Martínez
- Universidad Nacional Autónoma de México, Instituto de Quı́mica, Ciudad Universitaria, Ciudad de México 04510, México.,Centro Conjunto de Investigación en Quı́mica Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, km. 14.5, Toluca, Estado de México, C.P. 50200, México
| | - Diego Martı Nez-Otero
- Universidad Nacional Autónoma de México, Instituto de Quı́mica, Ciudad Universitaria, Ciudad de México 04510, México.,Centro Conjunto de Investigación en Quı́mica Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, km. 14.5, Toluca, Estado de México, C.P. 50200, México
| | - Brandon Meza-González
- Universidad Nacional Autónoma de México, Instituto de Quı́mica, Ciudad Universitaria, Ciudad de México 04510, México
| | - Fernando Cortéz-Guzmán
- Universidad Nacional Autónoma de México, Instituto de Quı́mica, Ciudad Universitaria, Ciudad de México 04510, México.,Centro Conjunto de Investigación en Quı́mica Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, km. 14.5, Toluca, Estado de México, C.P. 50200, México
| | - Vojtech Jancik
- Universidad Nacional Autónoma de México, Instituto de Quı́mica, Ciudad Universitaria, Ciudad de México 04510, México.,Centro Conjunto de Investigación en Quı́mica Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, km. 14.5, Toluca, Estado de México, C.P. 50200, México
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