Metal–Metal Synergy in Well-Defined Surface Tantalum–Iridium Heterobimetallic Catalysts for H/D Exchange Reactions

• Published in: Journal of the American Chemical Society Vol. 141; no. 49; pp. 19321 - 19335
• Main Authors: Lassalle, Sébastien, Jabbour, Ribal, Schiltz, Pauline, Berruyer, Pierrick, Todorova, Tanya K, Veyre, Laurent, Gajan, David, Lesage, Anne, Thieuleux, Chloé, Camp, Clément
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 11.12.2019; Amer Chemical Soc
• Subjects: additives; alkanes; catalysts; catalytic activity; Chemical Sciences; Chemistry; Chemistry, Multidisciplinary; deuterium; dimerization; iridium; Physical Sciences; Science & Technology; tantalum; METATHESIS CATALYSTS; NUCLEAR-MAGNETIC-RESONANCE; ORGANOMETALLIC CHEMISTRY; SULFATED ZIRCONIA; TOTAL-ENERGY CALCULATIONS; BASIS-SETS; POLYMERIZATION; MESOPOROUS SILICA; COMPLEXES BEARING; SOLID-STATE; hydrides; iridium; early/late heterobimetallics; Surface organometallic chemistry; catalysis; H/D exchange; tantalum
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.9b08311

A novel heterobimetallic tantalum/iridium hydrido complex, [{Ta­(CH2 t Bu)3}­{IrH2(Cp*)}] 1, featuring a very short metal–metal bond, has been isolated through an original alkane elimination route from Ta­(CH t Bu)­(CH2 t Bu)3 and Cp*IrH4. This molecular precursor has been used to synthesize well-defined silica-supported low-coordinate heterobimetallic hydrido species [SiOTa­(CH2 t Bu)2{IrH2(Cp*)}], 5, and [SiOTa­(CH2 t Bu)­H­{IrH2(Cp*)}], 6, using a surface organometallic chemistry (SOMC) approach. The SOMC methodology prevents undesired dimerization as encountered in solution and leading to a tetranuclear species [{Ta­(CH2 t Bu)2}­(Cp*IrH)]2, 4. This approach therefore allows access to unique low-coordinate species not attainable in solution. These original supported Ta/Ir species exhibit drastically enhanced catalytic performances in H/D exchange reactions with respect to (i) monometallic analogues as well as (ii) homogeneous systems. In particular, material 6 promotes the H/D exchange between fluorobenzene and C6D6 or D2 as deuterium sources with excellent productivity (TON up to 1422; TOF up to 23.3 h–1) under mild conditions (25 °C, sub-atmospheric D2 pressure) without any additives.